UNIVERSITY  OF  CALIFORNIA 
AT   LOS  ANGELES 


CONTRIBUTIONS   TO   A   SCIENCE 

OF 

NEMATOLOGY 


By 
N.'A.  fcOBB 


914  -  1935 


CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY 


Contents 


Page 


I.  Antarctic  Marine  Free-Living  Nematodes  of  the 

Shackleton  Expedition 1 

II.  North  American  Free-Living  Fresh-Water  Nema- 
todes     Z5 

III.  The  Asymmetry  of  the  Nematode  Bunonema  in- 

equale,  n.  sp 101 

IV.  Selachinema,  a  New  Nematode  Genus  with  Remark- 
able Mandibles 113 

V.  Notes  on  Nemas 117 

VI.  The  Mononchs,  a  Genus  of  Free-Living  Predatory 

Nematodes 129 

VII.  Filter-Bed  Nemas:   Nematodes  of  the  Slow  Sand 

Filter-Beds  of  American  Cities   189 

VIII.  The  Orders  and  Classes  of  Nemas 213 

IX.  One  Hundred  New  Nemas 

(Type  Species  of  100  New  Genera) 217 

X.  Howardula  benigna,  a  Nemic  Parasite  of  the 

Cucumber -Bee  tie 345 

XI.  Marionella '   353 

XII.  Greeffiella 359 

XIII.  An  Amendation  of  Hoplolaimus  Daday  1905  nee 

auctores 363 

XIV.  Notes  on  Paratylenchus,  a  Genus  of  Nemas   .  .  .   367 
XV.  Biological  Relationships  of  the  Mathematical 

Series  1,  2,  4,  etc 371 

XVI.  Nemic  Spermatogenesis  375 

XVII.  The  Screw  Nemas,  Parasites  of  Codfish,  Haddock 

and  Other  Fishes 388 

XVIII.  Ungella  secta  n.  gen.  n.  sp.,  a  Nemic  Parasite 

of  the  Burmese  Oligochaete  (Earthworm)   ....   394 

XIX.  A  New  Species  of  the  Nemic  Genus  Syringolaimus.   398 

XX.  The  Chromatropism  of  Mermis  subnigrescens  .  .  .   403 

XXI.  Survey  of  Nemas  in  Marine  Beach  Sand 411 

XXII.  The  Ambulatory  Tubes  and  Other  Features  of  the 

Nema  Draconema  cephalatum  413 

XXIII.  Observations  on  the  Morphology  and  Physiology 

of  Nemas 419 

XXIV.  The  Demanian  Vessels  in  Nemas  of  the  Genus 

Oncholaimus 423 

XXV.  Metoncholaimus  pristiurus  (Zur  Strassen).  .  .  .    439 
XXVI.  A  Key  to  the  Genera  of  Free-Living  Nemas   .  .  .    451 


£87184 


ANTARCTIC  MARINE 

FREE-LIVING  NEMATODES 

OF  THE 

SHACKLETON  EXPEDITION 

Contributions  to  a  Science  of  Nematology 
I 

BY 

N.   A.   COBB 


(With  fifty  illustrations  in  the  text) 


BALTIMORE 

WILLIAMS  &  WILKINS  CO. 
1914 


To  Shackleton 
And  his  Men, 

Who  to  bring  these  stranger  forms 

Braved  the  ice  and  cold 

Of  the  Southern  Main, 

This  tribute  from  a  comber  of  milder  shores. 


ANTARCTIC  MARINE 
FREE-LIVIXG  NEMATODES 

OF  THE 

SHACKLETON  EXPEDITION 

BY  N.  A.  COBB 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  l 


Nematodes  are  so  frequent  in  the  Shackleton  collections  as  to  prove 
the  seabottoms  of  the  farthest  south  to  swarm  with  these  little  beings. 
Hundreds  of  them,  male,  female  and  young,  were  taken  from  a  mere 
thimbleful  of  the  dredgings.  The  same  tale  comes  from  stations  wide 
apart.  Countless  myriads  find  sustenance  in  these  cold  dark  depths, 
and  must  in  their  turn  be  devoured  by  larger  forms,  until  the  series 
culminates  in  herds  of  seal  and  schools  of  whale.  "All  that  in  them  is," 
takes  on  added  meaning! 

Whence  do  these  nematodes  derive  their  sustenance?  The  stomachs 
of  a  number  of  the  species  contain  diatoms  with  such  regularity  as  to 
leave  no  doubt  that  these  microscopic  plants  constitute  a  main  food 
supply.  The  undigested  frustules  of  the  diatoms  are  voided  and  go  to 
make  up  the  permanent  sea  floor,  so  that  the  interesting  little  creatures 
whose  portraits  follow,  or  at  least  a  part  of  them,  assist  in  building 
what  some  future  epoch  may  disclose  as  dry  land  formations  of  diato- 
maceous  earth  as  remarkable  as  those  of  the  United  States  or  those 
of  Tripoli.  Some  of  the  other  species  appear  to  be  predacious,  though 
none  belong  to  the  truly  carnivorous  group  of  the  Enoplidae.  No  doubt 
the  greater  part  of  the  species  are  vegetarian. 

These  antarctic  species  are  on  the  whole  somewhat  smaller  than  those 
of  warmer  seas,  but  one  of  them,  that  mentioned  last,  is  a  veritable 

1 N ematology — a  contraction  of  Nematodology.  The  founding  of  this  branch 
of  science,  on  a  par  with  Entomology  for  example,  is  fully  justified  by  the  fact 
that  the  Nematodes  constitute  such  a  distinct  and  highly  characteristic  group  of 
organisms,  containing  an  enormous  number  of  species  readily  susceptible  of 
division  into  definite  Orders,  some  of  which  are  of  great  economic  importance. 


ANTARCTIC   MARINE 


giant  of  its  kind.  Seven  tropical  Monhysteras  taken  at  random  from 
the  writer's  collections  prove  to  average  hardly  50  per  cent  longer 
than  the  average  of  the  seven  polar  Monhysteras  here  described. 

There  is  little  evidence  that  these  polar  species  are  less  fecund  than 
those  found  elsewhere.  It  is  hardly  conceivable  that  the  body  tem- 
perature of  the  marine  polar  species  is  higher  than  that  of  the  water 
in  which  they  live,  namely,  near  the  freezing  point  of  fresh  water,  and 
yet,  in  spite  of  the  freezing  temperature,  and  the  long  polar  night, 
nematode  protoplasm  seems  to  glide  on  through  its  mitosis  dance  to 
much  the  same  purpose  as  if  bathed  in  equatorial  light  and  ensconced 
in  the  warm  pools  of  tropical  reefs. 

Through  long  residence  and  much  travel  in  Pacific  regions  the  writer 
has  had  unusual  opportunity  to  become  acquainted  with  their  charac- 
teristics, and  having  at 
times  paid  particular 
attention  to  the  marine 
nematodes  of  these  re- 
gions (map),  is  able 
from  personal  observa- 
tion to  say  concerning 
the  nematodes  Lieu- 
tenant Shackleton's 
expedition  brought 
from  the  far  South,  that 
in  nothing  are  they 
more  remarkable  than 
in  the  striking  resem- 
blance they  bear  to 
forms  found  in  the 
warmer  parts  of  the 
water  hemisphere. 

Their  nearest  known 
relatives  are  found  in 
Xew  Zealand  and  the 
islands  off  the  coast  of 
the  south  end  of  South 
America.  Nearly  all  of 
the  Shackleton  species  belong  to  known  genera,  and  the  two  new 
genera  are  nearly  related  to  genera  already  known,  Aplectus  to  the  known 
Plectus  and  Austronema  to  the  known  Monhystera. 


Fig.  1.  Marks  indicate  about  twenty  of  the 
author's  Xematode  Stations — Xorth  American,  Asi- 
atic, Australasian  and  Oceanic— at  the  great  ma- 
jority of  which  he  has  made  personal  examinations, 
and  with  the  nematode  fauna  of  which  the  Shackle- 
ton  nematode  collections  are  compared. 


FREE-LIVING  NEMATODES  5 

The  spermatogenesis  of  Terschellingia  polaris,  n.  sp.  presents  some 
very  interesting  features  which  are  noted  in  connection  with  the  de- 
scription. Kecently  it  has  been  suggested  that  of  the  two  kinds  of 
spermatozoa  Boveri  and  Schleip  have  shown  to  exist  in  the  males  of 
the  free-living  generation  of  Khabdias  bufonis,2  one  kind,  supposedly 
that  producing  males,  becomes  functionless,  thus  accounting  for  the 
succeeding  generation  consisting  solely  of  "parthenogenetic  females," 
found  in  frogs'  lungs.  The  spermatozoa  of  Ascaris  equorum3  and  (?) 
Cystidicola  farionis  f  have  been  shown  also  to  be  of  two  sorts.  In  all 
these  cases  the  two  kinds  of  spermatozoa  are  very  similar  to  each  other, 
so  much  so  that  the  differences  were  long  overlooked  by  keen  observers. 
In  Terschellingia  polaris  the  differences  in  the  male  generative  cells  are 
of  an  extremely  striking  character,  and  seem  to  lend  countenance  to 
the  earlier  suggestion  of  the  writer,  that  spermatocytes  may  in  their 
reduction  division  produce  polar  bodies  or  their  true  homologues,  abor- 
tive spermatozoa.  We  realize  now  that  there  has  been  too  large  a 
degree  of  assumption  in  taking  it  for  granted  that  all  four  of  the  sper- 
matozoa quartette  are  equivalent  simply  because  they  are  similar  in 
form  and  size.  A  careful  examination  of  their  structure  is  revealing 
important  differences. 

Very  possibly  it  is  a  comparatively  minor  phenomenon  that  the  polar 
bodies  of  eggs  remain  attached  to  their  larger  functional  companion 
cell.  Taking  this  view,  three  of  the  four  companion-spermatozoa  may, 
without  violence,  be  regarded  as  homologues  of  the  "polar  bodies." 
Whether  they  are  functional  or  not  is  a  matter  that  may  be  considered 
quite  apart  from  their  history  or  structure.  Generally  speaking  we 
know  little  or  nothing  about  their  relative  "potency."  That  all,  or  any 
definite  fraction  of  them  are  functional  is  more  or  less  pure  supposition. 
What  we  know  is  that  some  of  them  are  functional — perhaps  all,  per- 
haps not. 

Though  these  things  are  thus  far  outside  our  field  of  experience,  they 
constitute  problems  that  seem  certain  soon  to  be  attacked  from  the 
experimental  side,  by  following  the  history  of  specific  members  of  the 
spermatid  quartette;  and  one  object  of  this  note  is  to  call  attention  to 
the  fact  that  the  free-living  nematodes  offer  an  attractive  field  for  such 
work. 


2  Rhabdias  bufonis  (Schrank  1788)  S.  and  H.  1905  =  " Rhabditis  nigrovenosa." 

3  A  scan's  equorum  Goeze  1782  =  "A  scan's  megalocephala." 

4  (?)  Cystidicola  farionis  Fischer  1798  =  " A ncry acanthus  cystidicola." 


6  ANTARCTIC   MARINE 

Incidentally  there  is  raised  the  very  interesting  question  whether 
Terschellingia  polaris  may  not  be  the  free-living  form  of  a  dimorphic 
species  having  a  parasitic  stage  in  some  higher  antarctic  form.  It  is 
the  writer's  impression,  based  on  a  very  considerable  amount  of  obser- 
vation, that  numerous  free-living  nematode  forms,  marine  as  well  as 
land  and  fresh  water,  belong  to  such  dimorphic  species. 

The  following  diagram  illustrates  the  nature  of  the  formula  used  in 
the  tabulation  of  the  various  necessary  measurements : 


Fig.  2.    Diagram  of  the  descriptive  decimal  formula  used  for  nematodes ;  6,  7, 
8,  10,  6  are  the  transverse  measurements,  while  7,  14,  28,  50,  88  are  the  correspond- 
ing longitudinal  measurements.    The  formula  in  this  case  is : 
7.     14.    28.    50.    88. 
£      T! 8.     10.      6. 

The  unit  of  measurement  is  the  hundredth  part  of  the  length  of  the 
body,  whatever  that  may  be.  The  measurements  become,  therefore, 
percentages  of  the  length.  The  absolute  length  is  given  in  millimeters 
as  a  final  non-paired  term. 

The  measurements  are  taken  with  the  animal  viewed  in  profile;  the 
first  are  taken  at  the  base  of  the  pharynx,  the  second  at  the  nerve-ring, 
the  third  at  the  cardiac  constriction  or  end  of  the  neck,  the  fourth  at 
the  vulva  in  females  and  at  the  middle  (3/)  in  males,  the  fifth  at  the 
anus.  The  formulae  represent  the  average  of  several  specimens. 

When  the  specimens  were  received  from  Mr.  James  Murray,  the 
biologist  of  the  Shackleton  Expedition,  they  were  in  formalin.  They 
were  next  treated  with  cold  concentrated  solution  of  mercuric  chloride, 
then  stained  with  Mayer's  acid  carmine  and  finally  examined  in  balsam. 
It  is  W7ell  to  bear  these  facts  in  mind  in  reading  the  measurements,  as 
both  the  relative  and  absolute  measurements  vary  somewhat  with 
various  methods  of  fixation  and  preservation.  The  number  of  speci- 
mens and  their  state  of  preservation  is  noted  at  the  end  of  each  de- 
scription, and  from  the  data  a  rough  guess  may  often  be  made  as  to 
the  abundance  of  the  species  and  the  relative  frequency  of  the  sexes. 

By  the  use  of  suggestive  conventional  signs  the  formulae  are  made 
to  convey  considerable  additional  information.  Thus  the  formula  on  p. 
7  indicates  that  the  cuticle  is  traversed  by  rather  coarse  transverse  striae,5 

*  Formula  line  of  short  dashes.     See  table,  p.  7. 


FREE-LIVING  NEMATODES 


85. 
~  2  . 


-H 

T.T 


which  are  resolvable  into  rows  of  dot-like  markings6  modified  on  the  lat- 
eral fields,7  where  there  are  distinct  wings  to  the  cuticle,8  one  on  each  side 
of  the  lateral  lines.  The  N  \ 
excretory  pore  is  located 
near  the  lips,9  and  the 
tail  end  is  armed  with  ph 

iii!  i  •  sp 

caudal  glands  and  a  spin- 
neret.10 The  oesophagus  has  a  posterior  or  cardiac  bulb  two-thirds  as 
wide  as  the  base  of  the  neck.11  The  two  ovaries  are  symmetrically  ar- 
ranged, reflexed,  and  occupy  19  per  cent  of  the  length  of  the  body.12 
And,  similarly,  the  male  internal  sexual  organ  is  single  and  outstretched, 
and  occupies  56  per  cent  of  the  length  of  the  body. 

Among  the  dredgings  at  Ross  Island  were  three  containing  nematodes 
which  furnished  material  for  this  report.  These  three  were  marked: 
(1)  "Bay,  Cape  Royds,  in  10  to  20  fathoms  of  water,  May  81,  1908;"  (2) 
"Cape  Royds,  in  25  to  50  fathoms  of  water,  July,  1908;"  (3)  "Bay, 
in  13  fathoms  of  water,  April  30,  1908."  These  are  referred  to  in  the 
following  descriptions  as,  (1),  Bay,  Cape  Royds;  (2),  Cape  Royds; 
and  (3),  Bay. 

Terminology  relating  to  Striation  of  Cuticle. 


Tern 

250   

500 

Bather  fine 

750   

Fine 

"   1000   

Very  fine 

"   1500   or  more 

None 

The  camera  lucida  sketches  are  all  made  to  the  same  scale,  namely, 
a  magnification  of  750  diameters,  except  in  the  case  of  Thoracostoma, 
which  was  drawn  at  400  diameters.  The  sketches  may  be  relied  upon 
as  accurate.  Information  in  the  keys  is  not  repeated  elsewhere. 

8  Dots  above  and  below  the  line  between  the  second  and  third  terms. 

7  Modified  dots  outside  those  just  mentioned  in  6. 

8  Lines  above  and  below  the  formula  line  between  the  second  and  third  terms. 

9  Oblique  line  near  the  pharyngeal  terms  of  the  formula. 

10  Angular  mark  at  right-hand  end  of  formula. 

11  Underscoring  the  third  diametral  measurement,  thus  indicating  the  presence 
of  a  bulb.    Length  of  mark  indicates  the  size  of  the  bulb. 

12  Curved  marks  before  and  after  47,  and  19  used  as  an  exponent  figure. 
NOTE  :    Absence  of  any  particular  mark  indicates  the  absence  of  that  particu- 
lar feature  so  far  as  at  present  known. 


ANTARCTIC   MARINE 


KEY  BASS!)  OH  CHARACTERS  NOT  EMPHASISED  ELSEKHEf 


25  New  Species  and 
2  New  Genera 


-f-  Terschellingia  polaris  5 


meridiana  14 
edentata  16 


Austronema    spirurun  8 


. -n-  Monhystera 
.-F. -f  Monhystera 


pilosa 
unifonais 

frigida 


TAIL  CONOID, THEN  CYLINDROID,AT  LEAST  IN  FEMALES 
Posterior(cardiac)oesophageal  bulb  present 
"Bulb  oblate  :... • • 

Bulb  pyrifora 
Musculature  of  bulb  broken  into  2  parts  ; 

striae  resolvable  into  elongate  markings 

Wings  (interrupted  striae)  inconspicuous  'f  Chronadora 

Wings  pronounced -n 'f  Spilophora 

Musculature  of  bulb  unbroken;  striae  resolve 
into  dotlike  markings, at  least  on  head 

Striae  difficult  of  resolution Spira  septentrionalis   1 

Striae  easy  to  resolve 
Cardiac  bulb  three-fourths  as  wide  as  neck  ._-':' Spilophora  antarctica  17 

Cardiac  bulb  one-half  as  wide  as  neck  _--'f  Aplectus   antarcticus  '3 

Posterior(cardiac)oesophageal  bulb  none 

Anphids  almost  invisible  transverse  slits  ::ia    subsirailis  -2 

Anphids  circular, usually 'easy  to  see 

Pharynx  Plectoid, long, resembling  oesophagus  ..  - 

Pharynx  short,  often  small 

Intestinal  cells  clearly  reticulated  Sabateria   antarctica   4 

Intestinal  cells  not  clearly  reticulated 
Oesoph.  trifle  larger  fn. behind  nerveri 
Oesophagus  plain 
Renette  distinctly  developed 
Somatic  setae  as  long  as  body  is  wide 
Somatic  setae  none  or  inconspicuous  . 
Renette  inconspicuous  or  none 

Chromatin  bodies,  1  in  front  of  each  anph'd-n -f  Monhystera 
Chromatin  bodies  n'r.acphids  none  or  faint 
Contour  crenate.esp. vejitral  side  of  tail  ----f  Monhystera 

Contour  entire  -f  Monhys. septentrionalis 

TAIL  CONOID,  NO  PART  CYLINDROID 
Po3terior(cardiac)oesophageal  bulb  present 
Bulb  elongated, not  clearly  subdivided;  renette 

cell  probably  ellipsoidal  -?.--:"-  La  xus  septentrionalis 

Bulb  pyriform, musculature  broken  into  unequal 

parts;  renette  cell  elongated 

Contour  on  ventral  side  of  nale  tail  serrate  .-?.  'f  Spilophora 
Contour  entire 

Benette  cell  1/^wide  as  long ;Phar. bulb  faint  .-71   Chroiadora 
Renette  cell  ^  "  "       "   "  pronounced-:-  'f1  Euchr.  septentrionalis  19 
Posterior  bulb  none!12,13),  or  a  sere  swelling 
Striae  of  minute  BO re  or  less  elongate  elenents 

Dorsal  tooth  with  no  minute  dental  opponents  .-;?.  'f  Euchrorcad.  antarctica  20 
Dorsal  "  with  1  (22)  or  2  (21)  Subn.  "  " 

Tail  regular, terminus  about  Vg  wide  as  base  .   'f'  Euchronad.  denticulata  21 
Tarl±  suddenly  narrowed  on  Vent. side  n'r.anus  -n 'f'  Euchrosadora  neridiana 
Striae  appear  impossible  of  further  resolution 

Lips  strong, chi tinous,acute,conoid,eversible  .    Axonolaimrs    polaris 
Lips  not  acute, ±  nobile  but  not  eversible 

Cardiac  region  conspicuously  non-staining n-f  Monhystera   meridiana 

Cardiac  region  of  average  nature 

Unicellular  lateral  glands  and  pores  absent  _»-j  Monnystera  antarctica  13 
Unicellular  lateral  glands  and  pores  present---'!'  Thoracosio-a    polare  25 


polaris  10 
11 


23 


serrata  18 
polaiis  15 


22  . 


2-1 


12 


FREE-LIVING  NEMATODES 


KEY.  BASED  ON  MALE  CHARACTERS 


19  New  Species  and 

2  New  Genera 

PRE-ANAL  SUPPLEMENTARY  ORGANS  PRESENT 

Suppl. organs  IQ.submedian, in  2  rows  of  5  each  . . -m-f  Thoracostona    polare  25 
Supplementary  organs  in  a  single  ventral  row 
Organs  3(or  1  i  n  Anticoma  ),f  a  i  n  t  in  Sp  .serrata 
Fora  tubular, 1/5  as  wide  as  long 
Length  2/£  body  Diam.jjust  in  front  of  spicula, - 
Length  %  "   "  ;Ant.Org.  1  tail-L'gth.f  rin.anus  - 
Form  companulate.very  minute, deep  as  wide  .... 
Organs  7,equidistant>faint  in  Sp.edentata 
Form  cup-like, as  deep  as  body'wall  is  thick 

Cardiac  bulb  present  

Cardiac  bulb  reduced  to  a  faint  swelling  .. 

Form  papilloid.row  3  body-widths  long  

PRE-ANAL  SUPPLEMENTARY  ORGANS  ABSENT 
Accessory  pieces  to  spicula  absent  or  faint 
Spicula  suddenly  hookshaped  at  proxinal  end  . 
Spicula  of  usual  form, cephalated  by  expans 
Fora  arcuate, proximae  ventral  to  body  axi 


Anticoma  .subsiiilis  2 

-m-f  Aplectus  antarcticus  3 

-m 'f  Spilophora  serrata  is 

-m   Chromadora  polaris  15 

-n  T  Euchromad.  antarctica  20 

-n 'f  Spilophora  edentata  ie 

-m-f  Austroneraa  spirurum  Q 


Form  somewhat  L-shaped,Prox. dorsal  to  B'dy 
Accessory  piece  or  pieces  to  spicula  presen 
Apophysis  to  accessory  piece  bending  backw  rd 

Proximal  ends  of  spicula  not  cephalated  

Proximal  ends  of  spicula  cephalated 

Cephalated  by  constriction  

Cephalated  by  more  or  less  expansion 
Form  more  or  less  L-shaped 

Structure  rather  robust  

Structure       frail  

Form  nearly  straight, or  arcuate 

Spicula  nearly  straight  

Spicula  arcuate 

L'gth  2V%  times  anal  body  diameter 

L'gth  l1/^   ••    ••    -   »not  very  slender 
Apophysis  to  accessory  pieces  absent 

Spicula  cephalated  by  contraction  

Spicula  cephalated  by  expansion 

Cephalum  set  off  by  a  constriction  

Cephalum  not  set  off  by  a  constriction  


-a  t'  Spilophora  antarctica  17 
-m-f  Monhystera   raeridiana  12 


-n  -f-  Terschellingia  polaris  5 
-ra-f  Monhystera  antarctica  13 


-a— f  Monhystera    polaris  10 
-n -f  Monhystera     frigida  9 


-m-  Monhystera 


pilosa  7 


-m-f  Monhystera   uniforuis  Q 
-m— f-  Laxus  septentrionalis  23 

-;-  ':'  Euchromadora  meridiana  22 

-H 'f1  Euchr.  septentrionalis  19 
-m 'f  Spilophora  antarctica^ 


KEY  TO  SIGNS 

'f',  ovaries  2, symmetrical  .reflexed.  -^-.testes  2,  one  extending  each  way. 
-f-,    "    2     "  outstretched.  -n  ,  "    2,  one  only  outstretched  . 
-f  ,  ovary   1 .outstretched  forward,  -n  .testis  1,  outstretched   forward. 
Abbreviations 


Ib  ,  lip  or  lipregion 

on  ,  pnaryngeal  tooth 

am  ,  anphid 

Ic  ,  locule  of  cuirasse 


pp  ,  labial  papillae 
ph  ,  pharynx 
oe  ,  oesophagus 


st  ,  cephalic  setae 

sp  ,  spinneret 

ep  ,  excretory  pore 

pc  ,  cordifora  piece 


10  ANTARCTIC   MARINE 

DESCRIPTIONS  OF  THE  SPECIES 

CHARACTERS   COMMON  TO   ALL   THE   SPECIES 

Disregarding  Thoracostoma,  which  is  exceptional  in  the  large  size 
of  the  caudal  glands,  the  possession  of  eye-spots,  of  distinct  dermal  pores 
and  of  oesophageal  glands,  and  also  in  the  possession  of  relatively  very 
strong  spicula  with  a  compound  framework,  it  may  be  said  that  the 
following  characters  are  common  to  all  the  species  here  described: 

There  is  no  median  oesophageal  bulb,  and  no  pre-rectum.  The  tail 
is  of  approximately  the  same  form  in  both  sexes,  and  in  all  cases  is  sup- 
plied with  a  rather  simple  spinneret,  and  with  caudal  glands — the  lat- 
ter confined  to  the  tail.  The  eggs,  so  far  as  known,  are  smooth  and 
comparatively  thin-shelled,  and  are  deposited  before  segmentation 
begins. 

All  known  males  have  equal  spicula  of  simple  framework,  and  all 
are  without  bursa.  There  are  no  eye-spots.  The  cuticle  is  colorless, 
or  nearly  so,  is  without  distinct  pores,  and  is  destitute  of  longitudinal 
striae  except  obscure  indications  in  Spilophora  serrata  and  Chromadora 
meridiana,  where  the  secondary  elements  of  the  cuticle  arrange  them- 
selves also  to  a  certain  extent  in  longitudinal  lines. 

The  renette,  when  present,  has  its  cell  behind  the  cardiac  constriction, 
except  in  Anticoma.  Glands  in  the  interior  of  the  oesophagus  have 
been  seen  only  in  Thoracostoma,  and  possibly,  though  these  latter  are 
of  another  character,  in  Monhystera  frigida  and  polaris.  The  intestinal 
granules  give  rise  to  a  tessellation  only  in  Anticoma  and  Laxus.  The 
spicula  are  arcuate,  except  in  some  Monhysteras;  and  cephalated  except 
in  Anticoma,  Terschellingia  and  Euchromadora  antarctica.  There  are 
no  male  papillae  except  in  Anticoma  and  Monhystera  antarctica.  Male 
supplementary  organs  occur  only  in  Anticoma,  Chromodora  polaris,  Eu- 
chromadora antarctica,  Aplectus,  Thoracostoma,  and  in  Spilophora  ser- 
rata and  edentata.  The  musculature  of  the  oesophagus  is  fine  except  in 
Thoracostoma  and  Monhystera  polaris,  frigida  and  pilosa,  though  it  is 
somewhat  coarse  in  the  bulb  of  Laxus. 

If  the  reader  will  add  these  characters  to  those  given  under  each 
species  heading,  and  will  utilize  in  a  similar  way  the  common  charac- 
ters given  in  the  keys  and  generic  descriptions,  he  will  find  himself  in 
possession  of  a  very  detailed  description  of  each  species,  covering  a 
number  of  new  and  interesting  anatomical  features. 


FREE-LIVING   NEMATODES  U 

SPIRA,  Bastian,  186513 

1.  Spira  septentrionalis,  n.  sp.    The  striae,  invisible  except  near  the  head  are 
resolvable  into  rather  irregular  dots.    The  three  lips  are  without  papillae.    The 
i      7.4    10.6      Y       92.3  neck   is  cylindroid  posteriorly, 

s' i"g  •' "2 is j  7'  1-4nm'      convex-conoid  anteriorly.    The 

amphids,  seen  thus  far  only  in 

dorso-ventral  view,  have  a  central  elevation,  probably  appear- 
ing as  a  "fleck"  in  the  surface  view,  and  are  about  half  as  wide 
as  the  corresponding  diameter  of  the  head.  The  oesophagus 
is  half  as  wide  as  the  neck,  and  ends  in  a  rather  obscure  bulb  containing  an  in- 
distinct valve,  two-thirds  as  wide  as  itself.  No  distinct  cardia  was  seen.  The 
intestine,  separated  from  the  oesophagus  by  a  collum  about  half  as  wide  as  the 
neck,  becomes  at  once  three-fourths  as  wide  as  the  body;  it  is  but  a  few  cells  in 
girth,  and  the  cells  contain  few  or  no  granules.  The  rectum  is  conspicuous,  the 
posterior  lip  of  the  anus  prominently  elevated.  From  the  anus  the  tail  tapers 
for  two-thirds  of  its  length,  then  becomes  cylindroid  to  the  swollen  terminus, 
which  is  one-fifth  as  wide  as  the  base.  The  caudal  glands  were  not  clearly  seen, 
but  are  apparently  arranged  in  a  loose  tandem  in  the  anterior  third  of  the  tail! 
The  female  reproductive  organs  are  probably  double  and  reflexed. 

Habitat;  remarks.    Cape  Royds.    Described  from  a  single  somewhat  shrunken 
specimen. 

ANTICOMA,  Bastian,  1865 

2.  Anticoma  subsimilis,  n.  sp.    The  thin  cuticle  is  almost  invisibly  striated. 
On  each  lateral  line  there  is  a  row  of  five  somewhat  curved  cervical  setae, 
r'          26  si     8  each  having  a  length  equal  to  one- 

r-          '      '••'• :..»   i.5mm.      fourth  the  corresponding  width 

of  the   neck.    These   two   rows 

begin  at  a  distance  from  the  anterior  end  equal  to  nearly  three 
times  the  width  of  the  head,  and  have  a  length  equal  to  the  corre- 
sponding diameter  of  the  neck.  The  cuticle  becomes  thicker  at 
the  lips,  which  bear  a  circlet  of  six  papillae.  The  oesophagus  is  cylindroid  in 
the  anterior  part,  but  becomes  conoid  posteriorly.  The  mobility  of  the  lips  is 
proved  by  the  nature  of  the  ingested  food.  Seen  dorso-ventrally  the  pharynx 
appears  more  nearly  cylindroid  than  when  seen  laterally.  Seen  laterally  it 
tapers  so  that  finally  it  is  one-fifth  as  wide  as  the  corresponding  part  of  the  head. 
The  lining  is  rather  thin,  but  refractive.  The  cardia,  one-half  as  wide  as  the 
neck,  is  conoid  with  a  short  cylindroid  extension.  The  rather  thick-walled  in- 
testine, separated  from  the  oesophagus  by  a  collum  three-fifths  as  wide  as  the 
neck,  becomes  at  once  three-fourths  as  wide  as  the  body,  and  is  about  six  cells 
in  girth.  The  intestinal  cells  contain  numerous  small,  uniform,  distinct  granules. 
The  posterior  lip  of  the  anus  is  elevated.  The  caudal  glands  are  packed  together 

13  The  abbreviations  used  in  lettering  the  sketches,  which  represent  the  ante- 
rior and  posterior  extremities  respectively,  are  explained  near  the  foot  of  page  9. 
As  a  rule  the  information  given  in  the  sketches  is  not  repeated  elsewhere.  As 
far  as  possible  the  sketches  are  derived  from  typical  specimens. 


12  ANTARCTIC   MARINE 

in  the  anterior  two-fifths  of  the  tail.  The  elongated  renette-cell,  two  and  one- 
half  times  as  long  as  the  body-diameter,  and  one-fourth  as  wide  a?  long,  lies  a 
little  in  front  of  the  cardia,  and  is  not  re  flexed.  The  excretory  pore  is  somewhat 
behind  the  pharynx.  Distinct  nerve-cells,  more  numerous  behind  the  ring,  are 
arranged  (at  least  in  front  of  the  ring),  in  six  longitudinal  groups.  The  cylin- 
drical part  of  the  tail  is  about  one-tenth  as  wide  as  the  base. 

The  slender,  uniform,  but  rather  strong  spicula,  as  wide  as  the  narrowest  part 
of  the  tail,  are  twice  as  long  as  the  anal  body-diameter,  and  lie  with  their  proxi- 
mal ends  dorsal  to  the  body  axis.  The  proximal  eighth  of  each  spiculum  is  sep- 
arately more  or  less  arcuate,  so  that  one  may  speak  of  a  curved  cephalum  or 
proximal  end.  Two  separate  accessory  pieces,  rather  frail,  bent  at  the  distal 
end,  one-sixth  as  long  as  the  spicula  and  parallel  to  them,  form  a  rather  close 
collar  round  the  distal  ends  of  the  spicula.  On  each  side  of  the  b'ody  there  are 
four  equidistant,  ventro-submedian,  pre-anal,  papilla-like  setae,  one-sixth  as 
long  as  the  body-diameter,  extending  in  a  row  from  near  the  anus  to  near  the  sup- 
plementary organ.  There  are  about  three  ventro-submedian  post-anal  setae  on 
each  side  of  the  middle  part  of  the  tail. 

Habitat;  remarks.  Cape  Royds;  Bay,  Cape  Royds.  One  adult  and  several 
immature  somewhat  shrunken  specimens.  This  species  differs  from  A.  similis  in 
having  five  pectoral  hairs,  longer  setae,  a  sub-cyliridroid  pharynx,  and  an 
oesophagus  without  expansion  behind  the  nerve-ring 

APLECTUS,  new  genus 

Species  of  this  newly  proposed  genus  have  the  general  form  of  Plectus,  but  have 
the  phar3iix  less  definitely  developed,  and  the  renette-cell  farther  back  and  not 
reflexed.  They  differ  also  in  having  nearly  obsolete  lips,  and  a  nearly  cylindroid 
oesophagus  whose  small  cardiac  bulb  is  without  a  three-fold  striated  valve.  The 
spinneret  also  differs  from  that  of  Plectus,  as  shown  in  the  sketch.  The  male 
supplementary  organs  in  the  two  genera  also  differ  materially.  These  facts 
together  with  the  marine  habitat  and  the  relative  abundance  of  the  males  of 
Apleclus,  appear  to  make  necessary  a  separate  genus  for  the  reception  of  this 
antarctic  species.  The  following  is  the  type  species. 

3.  Aplectus  antarcticus,  n.g.,  n.  sp.  The  rather  thin  cuticle  is  traversed  by 
about  700  duplex  striae,  which  give  the  contour  an  obscurely  doubly  crenate 

appearance.    Two   wings,    separated 

• !     12:e-2I>. . .  '.51' . .  .87:  ,    e,,       by  a  distance  about  equal  to  the  width 

y^jj     .8      2.2~^  2.3,     2.4      1.9    '  Of  an  annule,  begin  near  the  middle 

**  — -Q  .:  si  of  the  neck  and  end  near  the  middle 

H/       '....:. -r;r..: •'•  >  .6mn.      of  the  tail.     Cervical  setae,   similar 

to  the  cephalic  setae,  occur  one  or  two 

on  each  lateral  line;  and  on  the  male  tail  there  are  setae,  one-third  to  one-eighth  as 
long  as  the  body  is  wide.  The  lips  are  very  small  and  difficult  to  observe.  The 
pharynx,  very  inconspicuous  and  hard  to  distinguish,  is  probably  double,  the 
narrow,  tubular,  anterior  part  extending  to  a  little  behind  the  amphids,  the  pos- 
terior part,  which  closely  resembles  the  oesophagus,  extending  nearly  halfway 
to  the  nerve-ring  where  there  is  a  break  in  the  musculature.  In  the  lateral  view 
there  are  seen  close  behind  the  cephalic  setae,  under  the  cuticle,  very  minute 


FREE-LIVING   NEMATODES  13 

bodies  that  stain,  of  which  those  most  clearly  seen  were  the  dorsal  and  ventral 
ones.  Probably  there  is  a  circlet  of  these  bodies.  Just  behind  these  stained 
bodies,  that  is,  a  little  behind  the  setae,  there  is  an  appearance  as  if  of  a  small 
quadrate  cavity,  one-third  as  wide  as  the  head.  This  is  not  a  cavity,  however. 
Its  posterior  limits  are  a  trifle  more  than  a  head-width  from  the  anterior  end. 
The  amphids  are  variable  in  size  and  form,. being  considerably  larger  and  slightly 
more  elongated  in  the  male.  The  posterior  border  appears  interrupted.  The 
slender  cylindroid  oesophagus,  is  probably  very  obscurely  Rhabditoid,  and  ends 
posteriorly  in  an  obscurely  rhomboidal  to  pyriform  bulb  or  swelling,  three-fifths 
to  two-thirds  as  wide  as  the  neck.  The  cylindroid  cardia,  one-fourth  as  wide  as 
the  body,  and  twice  as  long  as  wide,  is  really  a  modified  part  of  the  intestine,  and 
is  composed  of  small  strongly  staining  cells.  The  thick  walled  intestine,  sepa- 
rated from  the  oesophagus  by  a  collum  one-fourth  to  two-fifths  as  wide  as  the 
neck,  is  few,  probably  four,  cells  in  girth.  These  cells  contain  numerous,  indis- 
tinct, rather  fine  and  uniform  granules. 

The  tail,  tapering  from  the  anus,  is  cylindroid  in  the  posterior  two-fifths  and 
ends  in  an  almost  imperceptibly  swollen  apiculate  terminus  one-third  to  one-half 
as  wide  as  the  base.  The  caudal  glands  are  arranged  in  loose  tandem  in  the  an- 
terior half  of  the  tail;  their  ampullae  are  distinct  and  no  wider  than  the  ducts, 
but  stain  more  strongly.  The  elongated  renette-cell,  which  is  difficult  to  observe, 
is  as  long  as  the  body  is  wide,  and  one-fifth  as  wide  as  long,  and  occurs  at  a  dis- 
tance behind  the  neck  equal  to  eight  times  the  width  of  the  body.  The  very 
slender  duct,  invisible  except  where  stained,  empties  through  a  pore  apparently 
opposite  the  nerve-ring.  The  nerve-ring  surrounds  the  oesophagus  rather  squarely 
and  is  accompanied  by  somewhat  distinct  nerve-cells  rather  definitely  grouped. 
From  the  inconspicuous,  small  continuous  vulva  the  small  vagina  leads  inward 
halfway  across  the  body  to  the  straight  uteri.  The  rather  elongated  eggs  are 
two  to  two  and  one-half  times  as  long  as  the  body  is  wide,  and  fully  one-third  as 
wide  as  long.  The  broad  ovaries,  cylindroid,  but  tapering  near  the  extremities, 
reach  three-fourths  of  the  way  back  to  the  vulva,  and  contain  about  twelve  ova,  ar- 
ranged rather  irregularly.  The  spermatozoa  in  the  uterus  are  of  such  a  size  that 
it  would  take  at  least  seven  or  eight  side  by  side  to  equal  the  body-diameter. 

The  arcuate,  rather  strong,  sub-slender,  sub-acute  spicula,  one  and  one-fourth 
times  as  long  as  the  anal  body-diameter,  are  slightly  cephalated  by  expansion, 
the  cephalum  being  set  off  by  a  broad  shallow  constriction,  and  lie  with  their 
proximae  dorsal  to  the  body-axis.  There  are  two  rather  strong,  sub-slender, 
slightly  bent  accessory  pieces,  parallel  to  the  spicula  then  bending  away,  the 
applied  part  being  one-fourth  as  long  as  the  spicula.  The  receding  part  is  arcuate 
in  the  same  direction  as  the  spicula,  and  from  its  end  there  passes  a  strand  of 
muscle  to  the  ventral  body-wall  behind  the  anus.  The  ejaculatory  duct  is  one- 
fourth,  the  vas  deferens  and  cylindroid  testes  one-half  as  wide  as  the  body.  The 
blunt  blind  ends  of  the  testes  are  two-thirds  of  the  neck's  length  from  the  cardia 
and  one  and  one-half  times  the  tail's  length  from  the  anus,  respectively. 

The  protrudable,  sub-equidistant  supplementary  organs  are  separated  by  a 
distance  equal  to  nearly  one  and  one-fourth  times  the  body-diameter,  and  the 
posterior  one  is  located  at  a  distance  in  front  of  the  anus  equal  to  twice  the  anal 
body  diameter.  They  are  rather  straight  but  have  the  distal  third  bent  ven- 
trally,  and  the  distal  end  flattened  and  pulled  out  posteriorly  into  a  spur,  or 


14  ANTARCTIC   MARINE 

toe,  which  always  remains  outside  the  body.  The  entire  profile  contour  is 
like  that  of  a  high  boot  with  its  leg  bent  backward.  The  projecting  part  is  twice 
as  long  as  the  diameter  of  the  tube,  and  is  roughened  at  the  end  with  ten  or 
twelve  exceedingly  minute  striae  or  warts.  The  proximal  ends  of  the  organs  are 
rounded  and  not  cephalated. 

Habitat ;  remarks.  Bay,  Cape  Royds.  About  fourteen  females  and  six  males, 
in  good  condition.  The  sketch  is  that  of  a  female. 

SABATIERTA,  de  Rouville,  1903 

4.    Sabatieria  antarctica,  n.  sp.    Striae  about  800,  resolvable  with  great  dif- 
ficulty into  dot-like  markings.    There  are  no  lips.    The  tubular  pharynx,  ex- 
9.3.17.7        Y      as.  tending  to  opposite,  the  posterior 

2"."5  '   2.6 zTs 2". 4    '9na'        borders  of  the  amphids,  as  shown 

by  a  slight   accentuation  of  the 

lining,  is  surrounded  by  an  almost  imperceptible,  slightly  unsym- 
metrical  pharyngeal  bulb  three-fourths  as  wide  as  the  head.  At 
the  somewhat  oblique  nerve-ring  the  oesophagus  has  a  diameter 
equal  to  one-third  the  width  of  the  corresponding  part  of  the  neck,  but  swells 
posteriorly  to  two-thirds  the  width  of  the  base  of  the  neck.  The  rather  cylin- 
droid  cardia  is  one-third  as  wide  as  the  neck,  and  one  and  one-half  times  as  long 
as  wide.  The  thick-walled  intestine,  separated  from  the  oesophagus  by  a  collum 
two-thirds  as  wide  as  the  body-diameter,  soon  becomes  three-fourths  as  wide  as 
the  body  and  is  about  two  cells  in  girth.  From  the  elevated  posterior  lip  of  the 
anus  the  rather  prominent  rectum  extends  inward  and  forward  a  distance  equal 
to  the  anal  body-diameter.  From  the  anus  the  tail  tapers  for  three-fourths  of 
its  length,  then  becomes  cylindroid  to  the  slightly  swollen  terminus.  The  caudal 
glands  are  probably  small  and  near  the  anus. 

Habitat;  remarks.  Cape  Royds.  Described  from  a  single  young  specimen 
in  fair  condition. 

TERSCHELLINGIA,  de  Man,  1888 

5.  Terschellingia  polaris,  n.  sp.  The  cuticle  is  traversed  by  about  700  striae, 
plainly  visible  near  the  extremities  only.  Narrow  double  wings,  having  a  width 
about  equal  to  that  of  two  an-  33 

nules  of  the  cuticle,  begin  near          '  :8. .  .9:9:±15:5.T44:. .  .84:9,    73cra 

the  middle  of  the  neck.    The          _  :-        3.2      3.6      4.        2.5 

central  raised  body,  or  "fleck," 
of  the  amphid  stains  about  as 
strongly  as  the  nuclei  else- 
where in  the  body.  Very  minute,  inconspicuous  papillae,  probably  six  in  number, 
occur  on  the  confluent  lips.  The  vestibule  is  very  minutely  longitudinally  stri- 
ated. About  halfway  to  the  amphids  there  is  a  break  in  the  musculature  of  the 
oesophagus;  the  pharynx  probably  extends  to  this  point.  The  conoid  neck  con- 
tains a  cylindroid  oesophagus  which,  near  the  nerve-ring,  is  one-third  as  wide  as 
the  neck,  but  ends  in  a  bulb  five-sixths  as  wide  as  the  base  of  the  neck.  The 
lining  of  the  oesophagus  is  distinct,  its  most  prominent  optical  expression  being 
a  single  refractive  line.  The  cardiac  valve  causes  a  slight,  simple  modification 
in  the  lining,  one-eighth  as  wide  as  the  bulb.  The  more  or  less  thick-walled  in- 


FREE-LIVIXG   XEMATODES  15 

testine  is  separated  from  the  oesophagus  by  a  cardiac  collum  one-sixth  as  wide 
as  the  neck,  and  soon  becomes  two-thirds  as  wide  as  the  body.  The  first  few 
cells  of  the  intestine,  at  the  cardiac  region,  are  very  small,  with  relatively  large 
nuclei  that  stain  strongly.  The  intestine  is  separated  from  the  rectum  by  a 
pyloric  collum  one-fourth  as  wide  as  the  corresponding  portion  of  the  body. 
From  the  anus,  whose  posterior  lip  is  elevated,  the  chitinized  rectum  leads  in- 
ward and  forward  a  distance  equal  to  the  length  of  the  anal  body-diameter.  The 
granules  of  the  intestinal  cells  are  small  and  scarce. 

The  tail  tapers  from  the  anus  and  ends  in  a  slightly  swollen  terminus.  A  few 
small,  stiff,  cylindroid,  blunt  caudal  setae  are  to  be  seen,  mostly  about  one-fourth 
as  long  as  the  terminus  is  wide.  The  broadly  saccate  caudal  glands,  arranged  in 
a  loose  tandem  in  the  anterior  fourth  of  the  tail,  empty  through  distinct  ducts 
and  elongated,  narrow  ampullae.  What  appears  to.be  an  irregularly  ellipsoidal 
renette-cell  is  located  at  a  distance  behind  the  neck  equal  to  the  width  of  the  body; 
it  is  half  as  long  as  the  body  is  wide,  and  three-fourths  as  wide  as  long.  The 
nerve-ring,  which  surrounds  the  oesophagus  more  or  less  obliquely,  is  accompa- 
nied by  distinct  nerve-cells  definitely  grouped,  both  in  front  of  it  and  behind,  and 
extending  backward  to  near  the  cardiac  bulb.  From  the  small  and  inconspicuous, 
but  more  or  less  elevated  vulva,  the  conoid,  non-chitinized  vagina  leads  inward 
at  right  angles  to  the  ventral  surface  two-fifths  the  way  across  the  body.  The 
eggs  have  a  length  nearly  one  and  three-fourths  times  that  of  the  body-diameter, 
appear  about  half  as  wide  as  long,  and  have  been  seen  in  the  uterus  one  at  a  time. 
The  medium  sized,  more  or  less  tapering  ovaries  contain  fifteen  to  twenty  develop- 
ing ova,  for  the  most  part  flattened  and  arranged  single  file. 

The  more  or  less  slender,  sub-acute,  uniform,  slightly  yellowish  spicula  have 
a  simple  and  rather  strong  framework,  and  are  one  and  one-fourth  times  as  long 
as  the  anal  body-diameter.  The  proximal  ends  appear  to  lie  opposite  the  body 
axis.  The  triangular,  blunt  accessory  pieces  have  a  simple  and  rather  frail  frame- 
work; the  part  applied  to  the  spicula  is  one-fourth  as  long  as  they,  while  the  ta- 
pering apophyses  lie  a  little  backward  and  end  opposite  the  body-axis.  The  ejac- 
ulatory  duct  is  one-fourth,  and  the  testis  one-half,  as  wide  as  the  body.  The 
comparatively  few  (about  a  dozen)  primary  spermatocytes  occur  in  the  testis 
in  single  file,  then  come  three  pairs  double  file— these  latter  relatively  huge. 
That  is  to  say,  the  primary  soermatocytes  increase  much  in  size  and  then  divide 
transversely  into  very  unequal  parts,  a  small  distal  part  and  a  large  proximal 
part,  and  these  two  unequal  parts  divide  almost  simultaneously  in  the  longitudi- 
nal direction.  Thus  there  appear  four  cells  arranged  in  two  pairs  side  by  side,  a 
small  strongly  staining  pair  with  inconspicuous  nuclei,  and  a  large  pair  which 
do  not  stain  except  in  their  relatively  small  nuclei  which  show  about  seven  small 
more  or  less  globular  chromosomes.  These  two  divisions  represent  the  usual 
reduction  divisions,  and  give  rise  to  spermatozoa  of  very  different  size  and  ap- 
pearance. The  phenomenon  is  reminiscent  of  the  formation  of  the  polar  bodies. 
In  some  specimens  the  smaller  cells,  those  that  in  their  appearance  remind  one 
of  polar  bodies,  appear  as  if  divided  a  second  time,  but  there  is  uncertainty  about 
this.  It  is  the  writer's  intention  to  prepare  a  separate  report  on  this  species 
and  its  spermatogenesis. 

Habitat;  remarks.  Cape  Royds;  Bay,  Cape  Royds.  Numerous  specimens, 
mostly  somewhat  shrunken. 


16  ANTARCTIC   MARINE 

AUSTRONEMA,  new  genus 

The  single  species  for  which  this  new  genus  is  proposed  has  many  of  the  char- 
acters of  Monhystera,  but  differs  in  so  many  important  respects  as  to  call  for 
separate  classification.  The  principal  differences  of  generic  value  are  the  pos- 
session by  Austronema  of  an  oesophagus  altered  in  the  posterior  half,  a  well 
developed  ventral  gland,  special  lateral  cells,  hamate  spicula  without  acces- 
sory pieces,  and  glandular  (?)  organs  associated  with  the  spicula.  Other  minor 
differences  exist,  such  as  the  occurrence  of  the  special  group  of  setae  near  the 
middle  of  the  tail.  The  following  is  the  type  species. 

6.  Austronema  spirurum,  n.  g.,  n.  sp.  The  cuticle  is  traversed  by  exceedingly 
minute  transverse  striae.  The  lips  are  confluent.  The  conoid  neck  contains  a 

cylindroid  oesophagi!?,  whose  di- 
ameter measured  near  the  nerve- 
J  • 4  ring  is  one-half  as  great  as  that  of 

87  3  the  corresponding  portion  of  the 

2';  2"*  '8nn'  neck,   but  which  finally  becomes 

two-thirds  as  wide  as  the  base  of 
the  neck.  There  is  a  break  in  the  musculature  of  the  oesophagus  just  behind 
the  nerve-ring,  and  behind  this  break  the  refractive  nature  of  the  lining  is  some- 
what different,  and,  moreover,  in  many  of  the  preserved  specimens  the  diameter 
of  the  oesophagus  from  this  point  onward  is  suddenly  somewhat  greater.  There 
is  a  conoid  to  cylindroid  cardia  about  one-half  as  wide  as  the  base  of  the  neck. 
The  very  thick-walled  intestine,  two  to  four  cells  in  girth,  becomes  at  once  three- 
fourths  as  wide  as  the  body.  For  a  short  distance  behind  the  cardiac  collum, 
namely,  for  a  distance  about  equal  to  two-thirds  the  body  width,  the  tissues  of 
the  intestine  do  not  stain.  The  lining  of  the  intestine  is  refractive  and  distinct, 
so  that  the  almost  imperceptibly  zigzagged  lumen  can  be  readilv  followed.  The 
intestine  is  separated  from  the  oesophagus  by  a  collum  two-fifths  as  wide  as  tKe 
base  of  the  neck.  The  size  of  the  numerous,  yellowish,  uniform  granules  contained 
in  the  intestinal  cells  varies  in  the  different  parts  of  the  intestine;  they  are  much 
coarser  posteriorly  than  anteriorly.  From  the  anus,  the  posterior  lip  of  which 
is  elevated,  the  chitinized  rectum  extends  inward  and  forward  a  distance  equal 
to  the  anal  body  diameter. 

The  tail  tapers  in  such  a  manner  that  at  the  middle  its  diameter  is  about  half 
as  great  as  at  the  base.  Its  terminus  is  about  one-fifth  as  wide  as  its  base.  The 
ellipsoidal  caudal  glands  are  arranged  in  a  loose  tandem  in  the  anterior  third  of 
the  tail.  Very  short,  stiff,  inconspicuous,  ventrally  submedian  caudal  setae 
occur  on  each  side  of  the  tail,  two  on  the  anterior  half  of  the  tail,  and  three  near 
the  middle  and  close  together  and  finally,  one  or  two  on  the  cylindroid,  narrow, 
posterior  half.  The  pyriform  to  ellipsoidal  granular  renette-cell  is  located  at  a 
distance  behind  the  base  of  the  neck  equal  to  one  and  one-half  body-diameters. 
It  is  one  and  one-half  times  as  long  as  the  body  is  wide,  and  one-third  as  wide  as 
long,  and  presses  the  intestine  considerably  to  one  side.  It  does  not  appear  to 
have  any  companion  cell.  The  medium  sized  nerve-ring  surrounds  the  oesopha- 
gus somewhat  squarely,  and  is  accompanied  by  distinct  nerve-cells  extending 
well  back  toward  the  base  of  the  neck.  From  the  rather  small,  but  rather  con- 


FREE-LIVING   NEMATODES  17 

spicuous,  elevated  vulva,  the  well  developed,  tubular,  muscular  vagina  extends 
inward  and  obliquely  forward.  It  is  about  twice  as  long  as  the  corresponding 
body-diameter,  and  about  two-thirds  as  long  as  the  uterus.  The  eggs  are  about 
as  long  as  the  body  is  wide,  and  three-fourths  as  wide  as  long,  and  have  been  seen 
two  or  three  at  a  time  in  the  uterus.  The  ovary  is  of  medium  size,  and  tapers  so  as 
to  become  narrow.  It  contains  many  ova,  arranged  single  file— somewhat  irreg- 
ularly so  near  the  uterus. 

The  slender,  more  or  less  uniform  spicula  taper  from  the  middle  toward  the 
proximal  ends,  and  present  the  striking  peculiarity  of  being  strongly  curved  at 
the  distal  extremity,  forming  a  hook  across  which  there  is  a  thin,  transparent 
membrane.  They  are  one  and  three-fourths  times  as  long  as  the  anal  body-diam- 
eter, and  are  so  arranged  that  their  proximal  ends  appear  as  if  lying  to  the  dorsal 
side  of  the  body  axis.  Their  yellowish  framework  is  rather  strong,  and  the  proxi- 
mal two-thirds  may  sometimes  be  seen  to  be  nearly  straight.  At  the  extreme  end 
the  spicula  have  a  very  minute  recurved  apiculum  or  point.  Two  (?)  pairs  of 
ellipsoidal  granular  unicellular  glands  (?)  occur  some  distance  in  front  of  the 
spicula.  This  species  has  the  head  of  a  Monhystera  but  differs,  in  having  the 
oesophagus  altered  in  the  posterior  half,  a  well  developed  ventral  gland,  special 
lateral  cells,  hamate  spicula  without  accessory  pieces,  and  the  tail  with  a  group 
of  small  setae  near  the  middle. 

Habitat;  remarks.  Cape  Royds.  The  five  females  and  five  males  examined 
were  in  fair  condition. 

MONHYSTERA,  Bastian,  1865 

The  following  are  characters  common  to  all  the  species  of  Monhystera  here 
described. 

Cervical  and  somatic  setae  none  or  scattered  and  short,  except  in  M.  pilosa.  Neck 
conoid,  but  cylindroid  in  the  posterior  half  in  M.  pilosa,  and  M.  meridiana.  Tail 
tapering  from  the  anus  or  a  little  in  front  of  it.  Oesophagus  somewhat  cylindroid 
without  swellings  of  any  kind,  for  the  most  part  about  half  as  wide  as  the  nec'k, 
but  finally  three-fifths  to  three-fourths  as  wide  as  the  base  of  the  neck.  Cardia 
present,  except  in  M.  frigida,  hemispherical  to  cylindroid,  and  one-fourth  to  one- 
half  as  wide  as  the  base  of  the  neck.  Intestine  separated  from  the  oesophagus  by 
a  collum  one-third  to  one-half  as  wide  as  the  neck,  becoming  almost  at  once  about 
three-fourths  as  wide  as  the  body,  its  walls  thick  and  two  to  four  cells  in  girth, 
and  the  lining  usually  so  refractive  that  the  lumen  is  a  rather  distinct  feature. 
Granules  of  the  intestinal  cells  numerous,  fine  and  uniform.  Rectum  of  about 
the  same  length  as  the  anal  body  diameter.  Caudal  setae  none  or  inconspicuous 
except  in  M.  pilosa.  Lateral  fields  one-third,  more  rarely  one-half,  as  wide  as  the 
body.  Renette  unknown  except  in  M.  pilosa  and  M.  uniformis.  Nerve-ring  of 
medium  width,  surrounding  the  oesophagus  rather  squarely,  the  nerve  cells  in  its 
vicinity  usually  rather  diffusely  arranged.  Vulva  small  or  of  medium  size  and  in 
these  species  not  very  conspicuously  elevated  except  in  M.  uniformis.  Vagina  one 
to  two  times  as  long  as  the  body  is  wide,  and  extending  inward  and  forward. 

7.  Monhystera  pilosa,  n.  sp.  Striae  about  1700.  There  are  numerous  long,  very 
slender,  flexible  cervical  and  somatic  setae,  often  arranged  in  pairs,  one  member  of 


IS 


ANTARCTIC   MARINE 


the  pair  in  front 
of  the  other,  on 
the  sub-median 
lines.  There  are 
probably  three 
lips,  bearing  six 
minute  setose 
papillae  ar- 
ranged in  a  sin- 
gle circlet.  The 
lining  of  the  oe- 
sophagus is  very 
'  distinct,  and  the 
musculature 

rather  coarse.  The  granules  of  the  intestine  are  yellowish  brown.  Toward  the 
posterior  extremity,  for  some  distance  in  front  of  the  anus,  there  is  a  strong 
development  of  lateral  cells,  which  do  not  appear  to  exist  elsewhere  in  the 
body.  These  cells  extend  forward  toward  the  middle  of  the  body,  and  have  been 
traced  no  farther.  Their  size,  which  is  variable,  is  such  that  two  or  three  occur 
side  by  side  in  the  lateral  fields.  The  tail  is  cylindroid  in  its  posterior  three- 
fifths,  with  a  width  there  one-eighth  as  great  as  that  of  its  base,  and  has  a  slightly 
swollen  terminus.  The  caudal  ducts,  of  which  two  were  seen,  are  narrow  and 
distinct.  From  the  excretory  pore  at  the  end  of  the  third  fifth  of  the  neck 
there  leads  inward  a  very  narrow  duct  whose  length  is  nearly  equal  to  the  thick- 
ness of  the  cuticle.  The  duct  leading  thence  back  to  the  renette  cell  is,  however, 
of  considerable  width — about  one-fourth  as  wide  as  the  oesophagus — and  is  read- 
ily traced  back  to  a  point  opposite  the  anterior  part  of  the  intestine,  where  the 
renette  cell  pushes  the  intestine  to  one  side.  The  spicula  are  uniform,  with  a 
width  near  the  distal  extremity  one-sixth  as  great  as  the  corresponding  body 
width.  The  single  accessory  piece,  parallel  to  and  close  to  the  distal  thirds  of  the 
spicula,  has  an  apophysis  tapering  to  an  obscure  and  slightly  recurved  point.  This 
apophysis  lies  at  right  angles  to  the  spicula,  and  then  curves  forward  a  little.  The 
ejaculatory  duct  is  one-third  as  wide  as  the  body,  the  vas  deferens  considerably 
wider.  The  blind  end  of  the  anterior,  larger  testis  is  disposed  in  one  or  two  coils. 
Habitat;  remarks.  Bay,  Cape  Royds.  The  single  specimen  examined  was  in 
good  condition. 

8.  Monhystera  uniformis,  n.  sp.   Apparently  there  are  three  very  obscure  con- 
fluent lips.    The  amphids  when  seen  in  the  dorso- ventral  view  seem  to  be  well 

chitinized,  and  appear  deepest  in  the 
anterior  part,  where  they  are  one 
fifth  as  deep  as  the  head  is  wide.  The 
cardia  is  twice  as  long  as  wide.  The 
cylindroid  part  of  the  tail  is  one-third 
to  one-fourth  as  wide  as  the  base. 
Broadly  saccate  caudal  glands  are 

found  in  the  anterior  half  of  the  tail.  At  a  distance  behind  the  neck  equal  to  three 
to  four  body-widths  there  is  an  ellipsodial  renette  cell  with  a  large  nucleus.  This 
gland-cell  is  one  and  one-half  times  as  long  as  the  body  is  wide  and  half  as  wide  as 
long.  The  location  of  the  excretory  pore  has  not  been  made  out  with  certainty; 


13.2      20.      -83' 


.9      12.8      20.        -M 


FREE-LIVING   NEMATODES  19 

possibly  it  is  just  behind  the  nerve-ring.  The  small,  weak,  tubular,  non-chitinized 
vagina  leads  into  a  uterus  which  is  five  times  as  long  as  the  body  is  wide.  The 
eggs  are  about  four  times  as  long  as  the  body  is  wide,  and  one-fifth  as  wide  as 
long.  The  medium  sized  cylindroid  ovary  contains  about  twenty-five  ova, 
arranged  somewhat  irregularly.  The  tail  of  the  male  is  like  that  of  his  mate 
except  that  it  is  conoid  nearly  to  the  terminus.  The  very  slender  uniform  spicula 
are  two  and  one-half  times  as  long  as  the  anal  body  diameter.  Their  frame- 
work is  simple,  and  the  proximal  ends  lie  somewhat  dorsal  to  the  body  axis.  The 
single  accessory  piece  is  frail,  its  framework  simple;  the  applied  part  being  one 
eighth  as  long  as  the  spicula,  the  blunt,  backward  pointing  apophysis  being  one- 
fifth  as  long  as  the  anal  body  diameter  and  having  its  proximal  end  opposite  the 
body  axis.  The  ejaculatory  duct  is  one-third,  the  testis  two  thirds,  as  wide  as  the 
body. 

Habitat;  remarks.     Cape  Royds.     Six  females  and  three  males,  in  fairly  good 
condition. 

9.  Monhystera  f  rigida,  n.  sp.   About  1400  striae  give  to  the  margin  a  crenate  con- 
tour.   The  very  inconspicuous  lips  are  probably  three  in  number.    The  amphids 
appear  circular,  but  are  really  reg-  <  ^ ,  36 

ular  spirals  of  one  and  one-half  lb"~"/|P  "3  9'7  18>1  'B? 
winds,  having  a  raised  transverse 
ridge  extending  part  way  across. 
A  deeply  staining  nucleus,  of  the 
same  size  and  character  as  the 
nuclei  of  the  nerve  cells  near  the  ring,  occurs  immediately  in  front  of  each  amphid. 
In  the  posterior  end  of  the  oesophagus  there  are  two,  possibly  three,  elongated, 
granular  gland-cells,  quite  as  long  as  the  body  is  wide.  The  rectum  is  prominent. 
The  vagina  is  small  and  weak.  The  eggs  are  about  four  times  as  long  as  the  body 
is  wide.  The  rather  narrow,  cylindroid  ovary  contains  twenty  or  more  ova,  arrang- 
ed mostly  in  single  file.  The  uniform  slender,  frail,  sub-acute  spicula  are  one  and 
one-half  times  as  long  as  the  anal  body  diameter  and  lie  with  their  proximae  op- 
posite the  body  axis.  The  very  inconspicuous,  very  slender  and  frail  acces- 
sory piece  is  bent  so  that  the  applied  part  is  one-third  to  one-fourth  as  long  as  the 
spicula,  while  the  uniform  backward  bending  part  is  one-fifth  as  long  as  the  anal 
body  diameter.  Its  proximal  end  lies  to  the  ventral  side  of  the  body  axis.  The 
ejaculatory  duct  is  one-third,  the  testis  two-thirds,  as  wide  as  the  body. 

Habitat ;  remarks.    Cape  Royds.   The  single  female  and  the  two  males  examined 
were  in  fair  condition. 

10.  Monhystera  polaris,  n.  sp.    The  600  striae  give  to  the  margin  a  minutely 
crenate  contour,  most  plainly  to  be  seen  just  behind  the  anus.    The  three  double, 

more  or  less  distinct  lips 
^  j  4i  are  fairly  developed.  Two 

'->    i  BO  innervated  papillae  occur 

!       K5      2'5      2'6      3'4      2>1  on  each  of  the  lips,  six 

I  i.      11.      21.      -M-°    84.  papillae  in  all.    The  am- 

an w/?^-V'/,/      i.V^2.~5      2.V~  2.V~  2.7    Illma1'         phids    are    sunken,    but 

usually  show  a  well  stain- 
ed projecting  margin  two- 
thirds  as  wide  as  the  amphid.  A  little  in  front  of  each  amphid  is  a  single  some- 
what spherical  nucleus,  one-fourth  as  wide  as  the  oesophagus,  containing  granules, 


20  ANTARCTIC   MARINE 

as  do  the  ganglion  cells  near  the  nerve-ring.  These  two  neuclei  probably  indicate 
the  presence  of  two  nerve  cells.  They  are  best  seen  in  the  dorso-ventral  view.  The 
refractive  elements  of  the  lining  of  the  oesophagus,  especially  in  certain  aspects 
of  the  head,  appear  to  extend  into. the  pharynx  in  a  peculiar  way,  as  shown  in  the 
sketch.  The  rectum  is  more  or  less  prominent,  and  in  the  male  the  anus  is  raised. 
The  tail  tapers  in  such  a  manner  that  at  the  middle  it  is  one-third  as  wide  as  at 
the  anus.  Its  terminus  is  slightly  swollen.  Caudal  setae  appear  on  the  base  of  the 
tail. 

The  vagina  extends  inward  nearly  at  right  angles  to  the  body  wall,  about  half 
way  across  the  body.  The  uterus,  three  to  four  times  as  long  as  the  body  is  wide, 
contains  spermatozoa  one  fifth  as  wide  as  the  body.  The  posterior,  rudimentary 
branch  of  the  uterus,  nearly  twice,  as  long  as  the  width  of  the  body,  also  contains 
spermatozoa.  The  eggs  are  nearly  twice  as  long  as  the  body  is  wide,  and  one-third 
as  wide  as  long.  The  broad  tapering  ovary  contains  about  twenty  ova  arranged 
single  file,  and  as  many  more  packed  irregularly  in  the  distal  fourth. 

The  brownish,  rather  slender,  uniform,  acute  spicula  are  one  and  one-third 
times  as  long  as  the  anal  body  diameter.  The  framework  of  the  spicula  is  more  or 
less  strong,  and  the  proximal  ends  lie  opposite  or  a  little  dorsal  to  the  body  axis. 
The  single,  rather  straight  and  rather  frail  accessory  piece  is  of  a  simple  character, 
and  has  a  backward  pointing  apophysis  one-sixth  as  long  as  the  anal  body  diame- 
ter. The  male  presents  the  peculiarity  of  possessing  two  testes,  an  uncommon 
thing  in  Monhystera.  They  are  rather  wide  and  of  unequal  size,  the  anterior, 
more  or  less  cylindroid  one  being  considerably  the  wider.  The  blind  end  of  one 
testis  is  at  the  cardia,  that  of  the  other  about  one  tail-length  in  front  of  the  anus. 

Habitat;  remarks.  Cape  Royds;  Bay,  Cape  Royds;  Bay.  Seven  females  and 
six  males,  somewhat  shrunken.  The  specimens  from  the  various  localities  differ 
slightly  in  (1)  the  size  and  form  of  the  cephalic  setae,  (2)  the  length  and  width  of 
the  spicula,  (3)  the  prominence  of  the  amphids,  (4)  the  prominence  of  the  striae 
on  the  tail.  Diatoms  and  other  unicellular  organisms  were  seen  in  the  intestine. 

11.  Monhystera  septentrionalis,  n.  sp.    The  lips  are  confluent.    The  lining  of 
the  oesophagus  is  rather  prominent,  and  one-fifth  as  wide  as  the  oesophagus  itself. 

33  The  small  and  inconspicuous,  some- 

- — u'y — — ~E6        83-       .5mm.      what    ellipsoidal    caudal    glands    are 

1-9  arranged   in   a  loose  tandem   in   the 

anterior  half  of  the  tail.    The  anus  is  continuous.     The  conoid, 
rather  muscular  vagina  is  one  and  one-half  times  as  long  as  the  body 
diameter.    The  eggs  are  elongated,  twice  as  long  as  the  body  is 
wide,  and  less  than  half  as  wide  as  long.    About  thirty  ova  occur  in  single  file  in 
the  gently  tapering  ovary. 

Habitat;  remarks.  Bay,  Cape  Royds.  Seven  good  female  specimens.  The 
amphids  are  often  a  little  farther  back  than  illustrated. 

12.  Monhystera  meridiana,  n.  sp.    The  striae,  about  1000  in  number,  are  respon- 
sible for  a  somewhat  crenate  contour,  more  noticeable  near  the  tail.    The  strongly 
developed   cardiac  region,    set 

off  by  a  constriction  on  each 
side,  is  as  wide  as  the  intestine, 
and  forms  a  small  but  distinct 
segment  of  the  alimentary 
canal.  The  vulva  is  elevated. 
Eggs  twice  as  long  as  the  body 


FREE-LIVING   NEMATODES  21 

is  wide,  and  one-third  as  wide  as  long,  occur  in  the  straight  uterus.  Toward  its 
blind  end  the  narrow,  tapering  ovary  is  one-fourth  as  wide  as  the  body.  The  tail 
of  the  male  is  conoid  in  such  a  fashion  that  at  a  distance  from  the  anus  equal  to 
four  times  the  anal  body  diameter  it  has  a  width  equal  to  one-fourth  the  anal 
body  width;  thence  it  tapers  very  gradually  to  the  terminus,  whose  width  is  con- 
siderably less  than  that  of  the  spicula.  The  slender,  uniform,  acute  spicula  are 
one  and  three-fourths  times  as  long  as  the  anal  body  diameter.  Theejaculatory 
duct  and  vas  deferens  are  one-fourth  as  wide  as  the  body.  Apparently  there  are 
two  tapering  testes,  but  the  end  of  the  posterior  one  was  not  definitely  seen;  it 
appeared,  however,  to  be  eight  to  twelve  body  widths  in  front  of  the  anus. 
Spermatocytes  occur  in  single  file  near  the  end  of  the  anterior  testicle. 

Habitat;  remarks.  Bay,  Cape  Royds.  One  female  and  three  males  in  a 
somewhat  shrunken  state. 

13.  Monhystera  antarctica,  n.  sp.  The  cephalic  setae  are  very  minute  and  diffi- 
cult to  see.  Six  excessively  minute  forward  pointing  papillae  occur,  one  on  each 
lip.  Apparently  the  pharynx  is  tra- 
versed near  its  middle  by  a  trans- 
verse ridge,  and  this  is  the  reason  I  ^&\  !-2  2.7  2.9  3.7 
why  it  appears  in  optical  section 
as  if  armed  with  two  teeth.  From 
the  anus,  the  posterior  lip  of  which 
is  elevated,  the  rather  prominent,  chitinized  rectum  leads  inward.  Anal  glands 
are  present.  The  rather  large  and  conspicuous  nuclei  of  the  intestinal  cells  are 
arranged  about  a  body-width  apart.  The  terminus  of  the  tail  is  one-fourth  as 
wide  as  the  base.  The  broadly  saccate  caudal  glands,  of  which  two  are  larger  than 
the  third,  are  arranged  in  close  tandem  in  the  anterior  half  of  the  tail;  their 
ampullae  are  distinct.  The  lateral  fields  are  one-half  as  wide  as  the  body.  At  a 
distance  behind  the  base  of  the  neck  equal  to  four  times  the  width  of  the  body 
there  is  frequently  to  be  seen  in  the  female  a  large  cell,  one-half  as  wide  as  the 
body,  with  a  prominent  nucleus.  This  cell  occurs  in  females  only.  Though  its 
connections  have  not  been  definitely  made  out,  it  sometimes  seems  to  empty 
through  a  pore  a  little  in  its  rear.  The  straight  uterus,  five  to  six  times  as  long 
as  the  body  is  wide,  contains  elongated  eggs,  as  long  as  the  bodjr  diameter,  and 
half  as  wide  as  long.  The  cylindroid  ovary  contains  ova  arranged  in  double  file- 
irregularly  so  toward  the  blind  end. 

The  tail  of  the  male  is  a  little  stouter  than  that  of  his  mate.  The  rather  frail, 
slender,  uniform,  sub-acute  spicula,  one  and  one-half  to  one  and  three-fourths 
times  as  long  as  the  anal  body-diameter,  lie  with  their  proximae  dorsal  to  the  body 
axis.  The  single  accessory  piece,  parallel  to  the  distal  third  of  the  spicula,  and 
then  bending  back  in  a  thumb-shaped  apophysis,  lies  with  its  proximal  end  oppo- 
site the  body  axis.  On  the  tail  there  are  very  faint  inconspicuous  setose  papillae — 
one  ventro-submedian  on  each  side,  at  the  end  of  the  anterior  fourth,  and  two  or 
three  sub-ventral  just  behind  the  middle  of  the  tail.  The  ejaculatory  duct  is  one- 
fourth  to  one-third,  the  vas  deferens  and  tapering  testis  one-half,  as  wide  as  the 
body. 

Habitat ;  remarks.    Bay,  Cape  Royds.    Numerous  slightly  shrunken  specimens. 


22  ANTARCTIC   MARINE 

CHROMADORA,    Bastian,    1865 

14.  Chromadora  meridiana,  n.  sp.    Among  the  secondary  elements  into  which 
the  600  transverse  striae  are  resolvable  there  are  two  longitudinal  rows  that  stand 

°Ut    al°^    the    latfiral   fields   a 


'.6        8.8^13.8    '46          86. 

•.V~3.~3rr~3Y~5~~~?~2>  '9ia'  little  more  prominently  than 

the  others.  Outside  these,  on 

on''  ::*B*  either  side,  is  another  row  almost  imperceptibly  emphasized. 

SP  "  "-""  The  annules  are  retrorse  posteriorly,  and  the  reverse  anteriorly, 

the  change  taking  place  opposite  the  vulva  on  the  female.  The  few  very  short 
cervical  and  somatic  setae  to  be  seen  scattered  here  and  there  are  one-half  to  one- 
third  as  long  as  the  body  is  wide,  though  a  few  nearer  the  head  are  considerably 
longer  than  the  cephalic  setae.  There  appear  to  be  twelve  subdistinct  lips,  each 
bearing  a  single  papilla.  The  conoid  neck  contains  a  cylindroid  oesophagus, 
which,  measured  at  the  nerve-ring,  is  one-third  as  wide  as  the  corresponding 
portion  of  the  neck.  The  oesophagus  ends  posteriorly  in  a  bulb  three-fourths  as 
wide  as  the  base  of  the  neck,  containing  an  inconspicuous  elongated  valve  one- 
third  as  wide  as  itself.  The  musculature  of  the  bulb  is  broken  into  two  very 
unequal  parts.  There  is  no  cardia.  The  wall  of  the  intestine  varies  from  thick 
to  somewhat  thin,  and  is  six  to  eight  cells  in  girth.  The  intestine  becomes  at  once 
about  three-fourths  as  wide  as  the  body.  Its  lumen  is  distinct,  and  about  one- 
fourth  as  wide  as  itself.  The  rather  numerous  granules  to  be  seen  in  the  cells  of 
the  intestines  are  uniform  and  small.  From  the  anus,  which  is  depressed,  the 
chitinized  rectum  leads  inward  and  forward  a  distance  equal  to  the  length  of  the 
anal  body-diameter. 

The  arcuate  tail  tapers  from  in  front  of  the  anus,  but  is  usually  cylindroid  in  the 
posterior  fifth,  and  has  a  terminus  one-sixth  as  wide  as  its  base.  The  broadly  sac- 
cate caudal  glands  are  packed  together  in  the  anterior  fourth  of  the  tail,  and  empty 
through  distinct  narrow  ducts.  The  length  of  the  few,  scattered,  straight  caudal 
setae  is  about  equal  to  the  width  of  two  annules  of  the  cuticle.  The  lateral  fields 
are  one-third  as  wide  as  the  body.  The  granular  renette  cell,  which  is  somewhat 
longer  than  the  body  is  wide,  and  one  fourth  as  wide  as  long,  is  located  at  a  distance 
from  the  base  of  the  neck  equal  to  the  width  of  the  body,  and  empties  by  means  of 
a  slender  duct,  through  the  excretory  pore  located  at  the  lips.  It  has  a  smaller 
companion  cell  in  its  rear.  The  nerve-ring  surrounds  the  oesophagus  somewhat 
squarely.  The  cells  in  its  vicinity  are  distinct  in  character,  and  many  of  them  have 
narrow  connections  directed  forward.  From  the  obscurely  depressed  somewhat 
conspicuous  vulva,  the  small  tubular  vagina  leads  inward  at  right  angles  to  the 
ventral  surface  one-third  the  distance  across  the  body.  The  eggs  are  about  as 
long  as  the  body  is  wide,  and  usually  about  three-fourths  as  wide  as  long,  and  have 
been  seen  in  the  uterus  one  to  three  at  a  time.  The  spermatozoa  seen  in  the  females 
are  one-eighth  as  wide  as  the  body.  The  tapering  ovaries  reach  about  three- 
fourths  the  distance  back  to  the  vulva,  and  contain  each  about  fifteen  mostly  dis- 
coid ova,  arranged  more  or  less  single  file. 

Habitat;  remarks.    Bay,  Cape  Royds.    Five  females  in  fair  condition. 

15.  Chromadora  polaris,  n.  sp.  This  species  closely  resembles  Chromadora  me- 
•ridiana  from  the  same  region,  but  differs  in  having  narrower  dimensions,  more 


FREE-LIVING   NEMATODES  23 

slender  oesophagus,  bulb  and  intestine,   a  /  eo 

more  strictly  conoid  tail,  and  a  somewhat  .'--  -'->  i.r.a 

thinner  cuticule,  the  striations  of  which  are 

even  less  modified  on  the  lateral  fields.  There  are  about  four  hundred  and  fifty 
transverse  striae.  The  cuticle  is  hardly  perceptibly  modified  on  the  lateral  fields 
in  the  anterior  half  of  the  body,  but  in  the  posterior  half,  especially  opposite  the 
copulatory  muscles,  there  is  a  distinct  modification,  which  at  its  widest  part  is 
nearly  twice  as  wide  as  one  of  the  corresponding  striae.  The  modification  be- 
comes less  pronounced  behind  the  anus,  and  disappears  near  the  terminus.  The 
renette  cell  occurs  at  a  distance  behind  the  neck  equal  to  twice  the  diameter  of 
the  body. 

The  stoutish,  somewhat  tapering,  rather  blunt,  yellowish  spicula  are  one  and 
one-fourth  times  as  long  as  the  anal  body  diameter,  and  at  their  widest  point  one- 
sixth  as  wide  as  the  body.  They  are  almost  imperceptibly  cephalated  by  expan- 
sion and  lie  with  their  proximae  a  little  ventral  to  the  body  axis.  The  frame  has 
a  median  piece  from  near  the  middle  onward.  The  two  arcuate,  slender,  rather 
strong  accessory  pieces  are  three-fifths  as  long  as  the  spicula  and  lie  parallel  to 
them.  The  seven  chitinized  supplementary  organs,  separated  from  each  other 
by  a  distance  equal  to  the  diameter  of  one  of  the  organs,  occupy  a  space  about 
equal  to  one  and  one-half  times  the  body  diameter,  the  posterior  one  occurring 
about  opposite  the  proximal  ends  of  the  spicula.  These  organs  are  very  much  like 
those  of  Chromadora  minor.  The  ejaculatory  duct  and  vas  deferens  are  one- 
fourth,  the  broad  cylindroid  testis  one-half  as  wide  as  the  body.  Copulatory 
muscles  extend  forward  somewhat  beyond  the  supplementary  organs. 

Habitat;  remarks.     Bay,  Cape  Royds.     Two  good  specimens,  bothvmale. 

SPILOPHORA,  Bastian,  1865 

The  following  are  characters  common  to  all  the  species  of  Spilophora  here 
described. 

Cuticle  with  two  lateral  wings,  beginning  near  the  head  and  ending  on  the  tail. 
Neck  conoid.  Tail  tapering  from  somewhat  in  front  of  the  anus.  The  lips  are 
small  and  often  indistinct,  but  when  decipherable  can  usually  be  seen  to  be  twelve 
in  number,  each  with  a  single  forward-pointing  papilla.  Throughout  most  of  its 
length  the  oesophagus  is  more  or  less  cylindroid,  but  ends  posteriorly  in  a  pyriform 
bulb  two-thirds  to  four-fifths  as  wide  as  the  base  of  the  neck,  and  containing  a 
fusiform  valve  (sometimes  obscure)  one-fourth  to  one-half  as  wide  as  itself.  There 
is  no  distinct  cardia.  The  intestine  is  separated  from  the  oesophagus  by  a  distinct 
broad  constriction  about  one-third  as  wide  as  the  corresponding  part  of  the  body. 
The  more  or  less  prominent  chitinized  rectum,  about  as  long  as  the  anal  body  diam- 
eter, leads  inward  and  forward.  The  caudal  setae  are  small  and  scattered.  The 
nerve-ring  is  of  medium  size  and  surrounds  the  oesophagus  rather  squarely,  and  is 
accompanied  by  distinct  nerve  cells.  The  vulva  is  more  or  less  elevated  and  con- 
spicuous and  from  it  the  vagina  leads  inward  at  right  angles  to  the  ventral  surface 
about  half  way  across  the  body.  So  far  as  known  the  eggs  are  ellipsoidal.  The 
rather  slender,  blunt  spicula  are  about  one  and  one-fourth  times  as  long  as  the 
anal  body  diameter.  The  arcuate  accessory  piece  is  parallel  to,  and  half  to 
three-fourths  as  long  as,  the  spicula.  The  testis  is  relatively  wide. 


24  ANTARCTIC   MARINE 

16.  Spilophora  edentata,  n.  sp.    Striae  about  600,  producing  a  crenate  contour, 
interrupted  by  the  two  lateral  wings  which  are  so  formed  as  to  appear  somewhat 

like  the  keel  and  ribs  of  a 
boat.  Four  sub-cephalic 
setae  occur  opposite  the  base 

Pi—  7r£T:-  \-f     ^-J^Lzk.1^7---*5.6--8!'-  °f  the   phar>rnx-    There  are 

gp.J^:j--.-Y      i.~6~~3.2~r  3^3      3.~3  ~2.e    1<anp        f e w  subme dian  somatic 

setae,  each  about  one-third 

as  long  as  the  body  is  wide.  There  appears  to  be  no  distinct  dorsal  pharyngeal 
tooth,  but  possibly  an  exceedingly  minute  more  or  less  ventral  one, — unless  indeed 
this  appearance  be  due  to  the  optical  effect  of  one  of  the  striae  that  exist  separately 
in  the  posterior  part  of  the  pharynx.  The  masculature  of  the  bulb  is  broken  into 
two  very  unequal  parts.  The  rather  thin-walled  intestine  becomes  at  once  two- 
thirds  as  wide  as  the  body  and  is  about  six  cells  in  girth.  The  cells  contain  numer- 
ous very  small,  uniform  colorless  granules.  The  cylindrical  part  of  the  tail  of  the 
female  is  about  one-fourth  as  wide  as  the  base.  The  broadly  saccate  caudal  glands 
are  arranged  in  a  loose  tandem  in  the  anterior  half  of  the  tail,  and  are  connected 
with  the  spinneret  by  distinct  but  very  narrow  ducts  with  no  clearly  visible  am- 
pullae. The  lateral  fields,  one-third  as  wide  as  the  body,  contain  small  scattered 
nuclei,  as  well  as  others  less  numerous  and  twice  as  large.  The  granular  ellipsoidal 
renette  cell,  which  presses  the  intestine  to  one  side,  a  little  behind  the  neck,  is 
about  half  as  long  as  the  body  is  wide,  and  one  half  as  wide  as  long.  The  duct  is 
hardly  half  as  wide  as  one  of  the  annules,  and  the  ampulla,  opposite  the  base  of 
the  pharynx  is  almost  invisible.  The  excretory  pore  is  at  the  lips.  The  nerve  cells 
are  arranged  in  rather  indistinct  groups,  better  seen  behind  the  ring. 

The  male  tail  appears  to  be  more  nearly  conoid  throughout,  and  has  a  spinneret 
only  about  one-eighth  as  wide  as  its  base.  The  tapering  spicula  in  their  widest 
part  are  one-sixth  as  wide  as  the  corresponding  part  of  the  body,  and  are  cephal- 
ated  by  a  very  inconspicupous  constriction.  The  accessory  pieces  are  slender  and 
rather  frail.  The  testis  is  about  half  as  wide  as  the  body.  Rather  distinct,  well 
spaced,  oblique  copulatory  muscles  are  present  in  front  of  the  anus  for  a  distance 
equal  to  one  and  one-half  tail-lengths.  Apparently  pairs  of  male  glands,  emptying 
into  the  cloaca,  are  present  as  in  Euchromadora  and  Chromadora,  but  the  details 
remain  unknown. 

Habitat;  remarks.  Bay,  Cape  Royds.  A  single  female  and  four  males,  all  in 
fair  condition. 

17.  Spilophora  antarctica,  n.  sp.  Striae  about  400,  producing  a  somewhat 
crenate  contour,  and  interrupted  by  two  lateral  wings  separated  by  a  distance 

equal  to  one-fifth  the  body  dia- 

44?4    77.  meter.     Cervical  setae   occur — at 

3.2      2.      '5na>          least  near  the  head.    The  cardiac 
56  valve  is  simple  in  structure.    The 

"*"  •  8°:  >   .SDD.          relatively  somewhat   thick-walled 
3-3      2'6  intestine  soon  becomes  two-thirds 

as  wide  as  the  body,  and  is  about 

two  cells  in  girth,  these  latter  containing  scattered,  rather  uniform,  colorless 
granules.  The  posterior  lip  of  the  anus  is  more  or  less  elevated.  The  cylindroid 
part  of  the  tail  is  one-fifth  as  wide  as  the  base,  or  somewhat  less.  The  renette  cell 


FREE-LIVING   NEMATODES  25 

has  not  been  clearly  seen,  but  the  intestine  is  pushed  to  one  side  as  if  a  small  one 
were  present,  a  little  behind  the  neck.  The  nerve-cells  extend  past  the  base  of 
the  neck,  especially  on  the  ventral  side.  The  eggs  occur  one  at  a  time  in  either 
uterus.  The  rather  broad,  tapering  ovaries,  which  extend  two-thirds  of  the  way 
back  to  the  vulva,  contain  few  ova,  arranged  single  file.  The  testis  is  one-half  to 
three-fifths  as  wide  as  the  body. 

Habitat;  remarks.  Cape  Royds;  Bay,  Cape  Royds.  Six  females  and  three 
males,  in  a  somewhat  shrunken  state. 

18.  Spilophora  serrata,  n.  sp.  Striae  about  500,  interrupted  by  the  lateral 
wings,  which  occupy  a  space  equal  to  one-fourth  the  body  diameter.  The  second- 
ary elements  of  the  cuticle  j,  ^ 

appear  as  dots  on  the  head,      pp;  ^0£J!^\\     ?/u i-_E_:Ji'J_'_4i' ^l*.5, 

and  produce  a  punctate  lffi'."'-|^v-'  -  ••  1>5  2>6  ;  2^1  3-4  2-5 
appearance  there.  Four  °l'.-f^\  j  K  1P.8.i7.i  -HE9  86. 
rather  irregular  pairs  of  sub-  sp  'jjlJE&Jfj  l  ~E — 2  V:~  J  V  ~  3  ~7 — iT  '9"' 
cephalic  setae,  like  the  ceph- 
alic setae,  but  shorter,  mated  one  in  front  of  the  other,  occur  at  a  distance  from 
the  lips  equal  to  twice  the  width  of  the  head.  There  are  few  cervical  setae.  The 
vestibule  of  the  pharynx  is  longitudinally  striated.  This  is  one  of  the  few 
species  of  Spilophora  in  which  the  amphids  can  be  plainly  seen.  The  rather  thick- 
walled  intestine  soon  becomes  three-fourths  as  wide  as  the  body,  and  is  ten  to 
twelve  cells  in  girth,  the  cells  containing  numerous  uniform,  colorless  granules 
nearly  equal  in  diameter  to  the  width  of  one  of  the  annules  of  the  cuticle.  The 
posterior  lip  of  the  anus  is  elevated.  The  terminus  of  the  tail  is  about  one-sixth 
as  wide  as  its  base.  The  two  broadly  saccate  caudal  glands  are  arranged  in  close 
tandem  opposite  the  anus  and  in  the  anterior  fourth  of  the  tail.  Their  ampullae 
are  not  distinct.  The  third  caudal  gland  (?),  just  behind  the  anus,  is  a  strongly 
staining  cell,  with  a  duct,  or  connection,  that  reaches  to  near  the  terminus.  The 
non-granular  renette  cell,  one  body-width  behind  the  neck,  twice  as  long  as  the 
body  is  wide,  has  a  small  companion-cell  in  its  rear.  The  excretory  pore  is  probab- 
ly near  the  lips.  Opposite  the  renette  cell  there  are  two,  and  probably  three, 
ellipsoidal  cells  in  each  lateral  field,  each  cell  being  one-third  as  long  as  the  body 
is  wide,  and  one-third  as  wide  as  long.  These  cells  constitute  two  pairs,— or  three. 
The  eggs  are  about  one  and  one-half  times  as  long  as  the  body  is  wide,  and  two 
thirds  as  wide  as  long,  and  occur  in  the  uteri  one  at  a  time.  Each  of  the  medium 
sized,  tapering  ovaries  reaches  half  way  back  to  the  vulva,  and  contains  about 
fifteen  ova  arranged  single  file. 

The  strong,  rather  uniform,  colorless  spicula  are  cephalated  by  a  constriction 
and  are  obliquely  truncated  at  the  distal  end,  where  there  are  two  or  three  exceed- 
ingly minute  teeth.  The  subslender,  rather  strong  and  simple  accessory  pieces 
recede  a  little  from  the  spicula.  Of  the  slightly  elevated,  somewhat  protrudable 
supplementary  organs,  whose  width  is  about  equal  to  that  of  two  annules,  the 
hindermost  is  near  the  anus.  They  are  farther  apart  anteriorly,  the  distance 
between  the  first  and  second  equaling  one-third  of  the  body  width,  that  between 
the  second  and  third,  one  and  one-half  times  the  body  width.  The  ejaculatory 
duct  is  one-third  as  wide  as  the  body— the  vas  deferens  and  testis  one-half.  At 
least  one  pair  of  glands  of  the  kind  seen  in  the  males  of  Euchromadora  occurs  nearly 
twice  as  far  in  front  of  the  anus  as  the  terminus  is  behind  it;  each  gland-cell  is 


26  ANTARCTIC    MARINE 

/• 

fusiform,  one-half  as  long  as  the  body  is  wide,  and  one-half  as  wide  as  long.  Both 
of  the  males  examined  had  a  ventral  swelling  near  the  center  of  the  tail,  as  long  as 
the  corresponding  body  diameter. 

Habitat ;  remarks.  Bay,  Cape  Royds.  The  two  females  and  two  males  studied 
were  in  good  condition. 

EUCHROMADORA,  De  Man,  1886 

The  following  are  characters  common  to  all  the  species  of  Euchromadora  here 
described. 

The  neck  is  more  or  less  cylindroid  in  the  posterior  part,  but  usually  slightly 
conoid  anteriorly.  The  tail  tapers  from  in  front  of  the  anus,  and  has  no  terminal 
swelling.  Cervical  setae  none  or  small  and  scattered,  except  in  E.  septentrionalis, 
somatic  setae  none  or  very  inconspicuous.  Caudal  setae  none  or  inconspicuous, 
except  in  E.  denticulata.  Each  of  the  six  lips  is  double,  so  that  there  appear  to 
be  twelve  more  or  less  alike.  These  are  usually  distinct  when  the  mouth  is  open, 
but  so  folded  together  when  the  mouth  is  closed  as  to  become  less  distinct,  and  to 
impart  to  the  then  narrow  vestibule  a  longitudinally  striated  appearance.  Labial 
papillae  twelve,  in  a  single  circlet,  forming  the  apices  of  the  lobes  of  the  lips.  The 
pharyngeal  region  of  the  oesophagus  is  swollen,  so  as  to  form  a  faint  pharyngeal 
"bulb,"  rather  obscurely  pyriform  or  elongated  in  form.  The  oesophagus  is  cylin- 
droid in  the  anterior  half,  and  conoid  or  perhaps  clavate  in  the  posterior  part, 
but  is  without  a  true  cardiac  bulb  except  in  E.  septentrionalis.  Oesophageal 
lining  distinct,  often  increased  posteriorly.  There  is  no  distinct  cardia.  The 
rather  thin  walled  intestine  becomes  almost  at  once  three-fifths  to  three- 
fourths  as  wide  as  the  body  and  is  from  six  to  nine  cells  in  girth.  It  is  separated 
from  the  oesophagus  by  a  distinct  collum  one-fifth  to  one-third  as  wide  as  the 
corresponding  part  of  the  body.  The  chitinous  rectum,  as  long  as  the  anal  body 
diameter,  leads  inward  and  forward  from  the  more  or  less  elevated  anus.  The 
caudal  glands  are  found  in  the  anterior  fourth  of  the  tail  (and  in  E.  meridiana  also 
a  short  distance  in  front  of  anus),  and  empty  through  ducts  devoid  of  ampullae, 
except  in  the  case  of  E.  denticulata.  The  lateral  fields  are  about  one-third  as  wide 
as  the  body.  The  elongated,  granular  renette  cell,  one  to  two  body-widths  behind 
the  neck,  has  one  or  two  smaller  companion  cells  in  its  rear.  The  medium  sized 
nerve-ring  surrounds  the  oesophagus  rather  squarely.  From  the  somewhat  ele- 
vated but  rather  inconspicuous  vulva  the  vagina  leads  inward  at  right  angles  to 
the  ventral  surface  about  halfway  across  the  body.  The  reflexed,  tapering  ovaries 
reach  half  to  two-thirds  the  way  back  to  the  vulva,  and  contain  a  dozen  or  more  de- 
veloping ova,  arranged  more  or  less  irregularly,  especially  toward  the  blind  end. 
The  more  or  less  slender  spicula  are  sub-acute,  and  accompanied  by  arcuate 
parallel  accessory  pieces  half  as  long  as  themselves.  The  single  testis  is  cylindroid 
and  about  half  as  wide  as  the  body. 

19.  Euchromadora  septentrionalis,  n.  sp.  The  600  striae,  very  difficult  to  see 
except  at  the  extremities,  are  resolvable  into  minute  elongated  elements,  which 

are  interrupted  by  very  narrow 
and  inconspicuous  lateral 
3.2  2.3  '  wings,  beginning  near  the  head 

55  and  ceasing  near  the  end  of  the 

1. 6      10.4_,_16.6      -M          88. 

,  y     2  y.  y   •   ys-     3y   .«»».       tail.     Two  sub-cephalic  setae, 
nearly  as  long  as  the  cephalic 


FREE-LIVING   NEMATODES  27 

setae,  occur  one  in  front  of  the  other  on  each  sub-median  line,  at  a  distance  from 
the  head  end  equal  to  one  and  one-fourth  times  the  head  width.  The  cervical 
setae,  more  numerous  on  the  anterior  part  of  the  neck/  are  sometimes  longer  than 
the  cephalic  setae.  The  lips,  otherwise  typical,  have  successive  rings  of  elements 
surrounding  the  interior  of  the  vestibule.  The  oesophagus  is  one-third  as  wide  as 
the  neck,  but  swells  posteriorly  into  a  true  cardiac  bulb,  containing  a  fusiform 
valve  one-third  as  wide  as  itself.  The  intestinal  granules  are  scarce  and  colorless. 
The  elongated  caudal  glands  are  arranged  in  a  close  tandem,  and  have  distinct 
ducts.  The  renette  cell,  three  times  as  long  as  the  body  is  wide,  empties  through 
a  very  inconspicuous  pore  at  the  base  of  the  lips.  Strongly  staining,  elongated, 
distinctly  granular  bodies  are  found  in  the  lateral  fields  behind  the  neck.  They 
are  one-half  as  long  as  the  body  is  wide,  and  two-thirds  as  wide  as  long,  and  they 
occur  as  rightsand  lefts,  i.  e.  are  paired.  The  first  pair  is  one  body-width  behind 
the  neck,  and  the  successive  pairs,  continuing  to  the  anus,  are  separated  from 
each  other  by  a  distance  three  times  as  great  as  the  radius  of  the  body. 

The  tail  of  the  male  is  a  little  stouter  than  that  of  his  mate.  The  uniform, 
slender,  frail  spicula  are  as  long  as  the  anal  body  diameter,  and  one-twelfth  as 
wide  as  long.  There  are  two  strong  grooved  accessory  pieces,  twice  as  wide  as 
the  spicula,  bearing  excessively  minute  teeth  at  their  blunt  distal  ends.  There 
are  at  least  five  unicellular  clavate  glands  on  the  dorsal  side,  extending  in  front 
of  the  anus  for  a  distance  equal  to  the  length  of  the  tail.  First,  anteriorly  there 
is  a  pair,  then  a  second  pair,  then  apparently  a  single  one,  all  with  slender  ducts 
They  were  not  very  well  seen,  and  this  enumeration  may  not  be  exact. 

Habitat;  remarks.  Cape  Royds;  Bay,  Cape  Royds.  Numerous  specimens, 
somewhat  shrunken. 

20.  Euchromadora  antarctica,  n.  sp.  The  cuticle  is  traversed  by  about  550 
transverse  striae,  resolvable  into  dots  near  the  head,  and  into  basketwork-like 
markings  on  the  neck  and  else- 
where. These  striae  are  of  such 
a  size  as  to  give  rise  to  an 
obscurely  crenate  contour  line. 
There  is  a  simple,  very  obscure 
cardiac  valve,  one-third  as 
wide  as  the  base  of  the  oesophagus.  The  cells  of  the  intestine  contain  numerous 
rather  small,  colorless,  uniform  granules.  The  ellipsoidal  caudal  glands  are  ar- 
ranged in  a  loose  tandem,  and  empty  through  very  narrow  ducts.  The  renette 
cell  is  about  as  long  as  the  body  is  wide,  and  one-third  as  wide  as  long,  and  presses 
the  intestine  somewhat  to  one  side.  The  nerve-cells  around  the  oesophagus  are 
of  a  distinct  character,  but  are  scattered  so  as  to  exhibit  no  very  systematic 
arrangement.  The  prolate  to  ellipsoidal  eggs  are  considerably  longer  than  the 
body  is  wide,  and  three-fourths  as  wide  as  long.  They  have  been  seen  in  the 
uterus  one  at  a  time.  The  tapering  ovaries  contain  upwards  of  a  dozen  ova. 

The  slender,  uniform  spicula  have  a  more  or  less  frail  framework,  and  are  about 
twice  as  long  as  the  anal  body-diameter.  They  are  not  cephalated,  but  the  proxi- 
mal parts  are  somewhat  wider.  This  wider  part  lies  a  little  to  the  ventral  side 
of  the  body-axis,  that  is,  it  appears  to  do  so  when  the  animal  is  viewed  in  profile. 
The  single,  slender  accessory  piece  has  a  framework  that  is  more  or  less  frail, 
and  has  its  proximal  end  opposite  the  body-axis.  The  supplementary  organs  are 


28  ANTARCTIC   MARINE 

spread  along  a  distance  about  equal  to  five  or  six  body-diameters,  the  distance 
between  the  adjacent  organs  being  about  equal  to  the  radius  of  the  body.  These 
organs. are  of  such  a  nature  that  when  the  body  is  stretched  out  they  hardly  dis- 
turb the  ventral  contour,  but  when  the  tail  end  is  incurved,  as  is  often  the  case, 
they  become  slightly  raised,  so  that  the  altitude  is  about  equal  to  one-half  the 
width  of  one  of  the  annules  of  the  cuticle.  In  this  contracted  condition  of  the 
ventral  surface  of  the  body  the  distance  between  the  organs  is  about  equal  to 
their  own  diameter.  The  ejaculatory  duct  is  one-fourth,  the  vas  deferens  three- 
fourths,  and  the  testis  two-fifths  as  wide  as  the  corresponding  portions  of  the 
body.  The  testis  is  cylindroid.  Rather  distinct,  oblique  copulatory  muscles 
are  found  coextensive  with  the  supplementary  organs. 

Habitat;  remarks.    Cape  Royds;  Bay,  Cape  Royds.    Numerous  specimens, 
somewhat  shrunken. 

21.  Euchromadora  denticulata,  n.  sp.     Striae  about  400,  resolvable  into  bas- 
ketwork-like  markings  of  a  rather  obscure  character  on  the  anterior  part  of  the 

neck.    The  lips  are  sub- 

2.4     14.'      26.      53 Y      83.  distinct.     At    the  nerve- 

~I.~2~~ir4~~I.~7~~3.~V  ring  the  oesophagus   has 

a  diameter  equal  to  two- 
fifths  the  corresponding  diameter  of  the  neck,  but  swells 
posteriorly  to  three-fourths  the  corresponding  diameter. 
In  the  posterior  swelling  the  lining  is  somewhat  expanded. 

The  dimly  seen  pyloric  collum  is  one-third  as  wide  as  the  body.  Intestinal 
granules  are  scarce.  The  ellipsoidal  caudal  glands  occur  in  a  close  tandem 
opposite  the  anus  and  in  the  anterior  fourth  of  the  rather  massive  tail.  The 
caudal  setae,  six  ventro-submedian,  and  six  dorso-submedian,  are  slender,  stiff, 
somewhat  cylindroid,  sub-acute,  and  one-sixth  as  long  as  the  anal  body-width. 
The  renette-cell,  two-thirds  as  long  as  the  body  is  wide  and  one-third  as  wide  as 
long,  empties  through  a  pore  opposite  the  nerve-ring.  In  both  the  specimens 
examined  there  appears  a  slender  seta-like  appendage  (?)  at  the  mouth  of  the 
excretory  pore.  The  female  reproductive  organs  are  double  and  symmetrical, 
and  probably  reflexed. 

Habitat;  remarks.    Cape  Royds.    Two  females,  in  fair  condition. 

22.  Euchromadora  meridiana,  n.  sp.    The  cuticle  is  much  like  that  of  Euchro- 
madora vulgaris,  (Bast.)  de  Man.    400  striae,  retrorse  posteriorly  and  the  reverse 
anteriorly,  make  the  con-  33 

tour    obscurely    crenate.     PP "  \l^V~  •JL_6J_4^-1_i:l 

The    oesophagus,    cylin- 

droid   anteriorly,   conoid  <          .          -  < 

posteriorly,    has    several        ......  8.4 

breaks  in  its  muscula- 
ture, the  most  prominent  being  at  the  beginning  of  the  final  fifth  of  the  neck. 
The  numerous  intestinal  granules  are  small,  uniform,  and  indistinct.  The  rather 
ellipsoidal  caudal  glands  are  arranged  in  an  open  tandem.  Immediately  behind 
the  anus  the  tail  has  a  diameter  equal  to  three-fourths  the  anal  body-diameter; 
thence  onward  it  tapers  but  very  slightly  to  the  middle,  where  it  begins  to  taper 
more  rapidly  to  the  terminus  which  is  one-third  as  wide  as  the  anal  body-diameter. 
The  lateral  fields  are  somewhat  distinctly  cellular.  The  renette-cell,  which  pushes 


FREE-LIVING   NEMATODES  29 

the  intestine  to  one  side,  is  twice  as  long  as  the  body  is  wide,  one-fourth  to  one- 
fifth  as  wide  as  long.  Just  behind  the  nerve-ring  there  is  a  large  ampulla  as 
long  as  the  body  is  wide,  and  one-third  as  wide  as  long.  In  all  the  specimens 
examined  there  appears  a  slender  seta-like  appendage  at  the  mouth  of  the  excre- 
tory pore  somewhat  longer  than  the  cuticle  is  thick.  The  ovaries  are  broad. 

The  male  tail  is  like  that  of  the  female,  but  more  uniformly  tapering,  with 
less  of  a  diminution  just  behind  the  anus.  The  strongly  arcuate,  sub-slender, 
rather  strong  and  tapering  spicula,  somewhat  cephalated  at  the  tapered  distal 
ends,  are  one  and  two-thirds  times  as  long  as  the  anal  body-diameter,  and  lie 
with  their  proximae  slightly  ventral  to  the  body-axis.  There  are  two,  more  or 
less  separate  accessory  pieces,  each  in  two  parts,  one  behind  the  spicula;  the 
other  in  front  or  alongside,  the  front  part  being  like  a  reduced  spiculum.  The 
ejaculatory  duct  is  one-fifth,  the  vas  deferens  one-half  as  wide  as  the  body. 

Habitat;  remarks.  Cape  Royds;  Bay.  About  a  dozen  somewhat  shrunken 
specimens,  the  two  sexes  occurring  in  about  equal  numbers. 

LAXUS,  Cobb,  1894 

23.  Laxus  septentrionalis,  n.  sp.  There  are  upwards  of  1000  plain,  transverse 
striae  so  small  as  to  be  difficult  of  resolution.  The  three  subdistinct,  more  or 
less  bluntly  conoid  lips 
are  united  by  a  mem- 
brane,  and  form  a  circlet 
around  the  mouth,  very 
difficult  to  see,  except 
when  the  mouth  is  open. 
Only  when  the  mouth  is  open  can  the  connecting  membrane  be  seen.  It  is  prob- 
able that  the  pharynx  contains  an  obscure  dorsal  tooth.  The  structure  which 
gives  rise  to  this  supposition  is  of  fair  size,  and  thinly  covered  wyith  chitin.  The 
cylindroid  to  conoid  neck  contains  a  cylindroid  oesophagus,  which,  measured 
near  the  nerve-ring,  is  one-half  as  wide  as  the  corresponding  portion  of  the  neck. 
Though  the  amphids  appear  circular,  they  are  in  reality  spiroidal.  The  pharynx 
is  situated  in  the  midst  of  an  almost  imperceptible  elongated  pharyngeal  swell- 
ing, two-thirds  as  wide  as  the  head.  The  thick  walled  intestine,  six  cells  in  girth, 
soon  becomes  five-sixths  as  wide  as  the  body.  It  has  a  distinct  lumen,  and  is 
separated  from  the  oesophagus  by  a  collum  hardly  one-third  as  wide  as  the  base 
of  the  neck.  For  a  distance  about  equal  to  the  length  of  the  body-diameter  the 
cells  of  the  intestine  are  comparatively  free  from  granules.  Thereafter  they  are 
uniformly  packed  with  yellowish  granules  having  a  width  a  little  greater  than 
that  of  one  of  the  striae  of  the  cuticle.  From  the  continuous  anus  the  prominent, 
chitinized  rectum  extends  inward  and  forward  a  distance  three-fourths  as  great 
as  the  length  of  the  anal  body-diameter. 

The  tail  tapers  froni  the  anus  to  a  terminus  one-third  as  wide  as  its  base.  Ap- 
parently the  ellipsoidal  caudal  glands  are  packed  together  somewhat  behind  the 
middle  of  the  tail.  Their  ampullae,  near  the  terminus,  are  more  or  less  distinct. 
The  lateral  fields,  which  are  one-third  as  wide  as  the  body,  are  margined  by  re- 
fractive lines,  at  least  in  balsam  specimens.  The  renette  has  not  been  clearly 
seen,  but  is  supposed  to  be  located  at  a  distance  behind  the  neck  equal  to  the 


30  ANTARCTIC   MARINE 

radius  of  the  body,  and  to  be  about  one-half  as  long  as  the  body  is  wide,  and  one- 
half  as  wide  as  long.  It  empties  by  means  of  a  short  duct,  and  a  rather  struc- 
tureless ampulla  half  as  wide  as  the  oesophagus,  through  the  excretory  pore  near 
the  nerve-ring.  The  vulva  is  more  or  less  continuous,  and  rather  inconspicuous. 
The  elongated  eggs  are  one  and  one-half  times  as  long  as  the  body  is  wide,  and 
one-third  as  wide  as  the  body.  They  have  conspicuous  nuclei.  Of  the  narrow 
ovaries  the  posterior  one  is  only  one-third  to  one-half  as  long  as  the  anterior, 
which  contains  twenty  developing  ova,  arranged  single  file,  while  the  posterior 
one  contains  only  about  fifteen. 

The  slender,  uniform  spicula  have  a  more  or  less  frail  framework.  The  single 
accessory  piece,  also  more  or  less  frail,  presents,a  stoutish,  uniform,  blunt  apoph- 
ysis  one-half  as  long  as  the  anal  body-diameter,  arranged  at  right  angles  to  the 
part  which  is  applied  to  the  spicula.  This  latter  is  one-third  as  long  as  the  spic- 
ula. The  vas  deferens  is  one-third,  the  tapering  testes  about  one-half  as  wide  as 
the  body.  These  latter,  however,  finally  become  very  narrow.  The  blind  end 
of  the  posterior  testis  lies  in  front  of  the  anus  a  distance  about  equal  to  six  times 
the  length  of  the  tail. 

Habitat;  remarks.  Bay,  Cape  Royds;  Bay.  Four  females  and  two  males, 
slightly  shrunken. 

AXOXOLAIMUS,  de  Man,  1889 

24.  Axonolaimus  polaris,  n.  sp.  The  striae  of  the  thin  cuticle  are  very  difficult 
to  resolve  and  are  best  seen  on  and  near  the  tail.  One  is  left  in  doubt  as  to  whether 

4   9        7    3        Y          94.7  the    COnt°Ur    is    Plain>   or  VeiT  mi' 

' • '••£",  i-7r.n.     nutely  crenate.    Apparently  there 

are    six    subcephalic    setae,    each 

half  as  long  as  the  diameter  of  the  head  measured  at  the  labial 
CP  \  '  \  constriction.  Though  there  are  no  somatic  setae  there  are  a 

few  scattered  setae  on  the  neck,  generally  somewhat  shorter 
than  the  subcephalic  setae.  The  conoid  neck  contains  a  conoid  oesophagus, 
whose  diameter  near  the  nerve-ring  is  two-fifths  as  great  as  that  of  the  corre- 
sponding part  of  the  neck,  and  which  finally  becomes  two-thirds  as  wide  as  the 
base  of  the  neck.  There  is  no  distinct  cardia.  The  thick  walled  intestine  is 
two  to  three  cells  in  girth,  and  becomes  at  once  three-fourths  as  wide  as  the 
body,  being  separated  from  the  oesophagus  by  a  collum  three-fifths  as  wide  as 
the  base  of  the  neck.  On  account  of  the  food  contained  in  it  the  lumen  of  the 
intestine  is  distinct.  The  intestinal  cells  contain  very  fine,  scattered,  colorless 
granules  in  the  middle  of  which  the  nucleus  appears  as  a  distinct  feature  in 
stained  specimens.  From  the  raised  anus  the  chitinized  rectum  extends  inward 
and  forward  a  distance  equal  to  the  anal  body-diameter.  The  tail  tapers  from 
the  anus,  bears  very  minute  hairs  near  the  end,  and  contains  broadly  saccate 
caudal  glands  packed  in  its  anterior  third.  The  nerve-ring  surrounds  the  oesoph- 
agus squarely,  is  of  medium  size,  and  is  accompanied  by  obscure  nerve-cells, 
which  are  not  very  distinctly  grouped. 

Habitat;  remarks.  Bay,  Cape  Royds.  Single  young  specimen,  in  fair  con- 
dition. In  the  sketch  the  lips  are  shown  partly  everted. 


FREE-LIVING   NEMATODES  31 

THORACOSTOMA,  Marion,  1870 

25.  Thoracostoma  polare,  n.  sp.  The  thick  yellow  cuticle  is  traversed  by  mi- 
nute, transverse  striae  difficult  of  resolution,  and  in  its  deeper  layers,  at  least 

near     the     head,    by     fine      ^_J«V^  38 

oblique  striae  crossing  each  lfc  -1^  V\  :-  -8-  14<  t<5°'  "'? 
other  at  an  angle  of  about  pc  .--/t--r*f'  ^  \  '4  1-  "3  1-5  '8 
forty-five  degrees.  Subce-  \*-'ffij$M\  .2  4.9  12.  _M-69  99.4 

phahc    setae,    like    the    ce-    \^r^\\\j/^  \    .4 i'g i';'3' i'T '^   i9.»a 

phalic  in  form  and  size,  oc- 
cur in  groups  of  three  or  four  together,  near  the  border  of  the  "cuirasse,"  and  a 
little  farther  back.  Similar  cervical  setae  occur  on  the  anterior  part  of  the  neck 
singly  and  separated  by  a  distance  one-fourth  to  one-third  as  great  as  the  diame- 
ter of  the  neck  measured  at  the  middle.  The  remaining  cervical  setae  as  well  as 
the  somatic  setae  are  reduced  to  papillae.  All  these  setae  are  arranged  in  more 
or  less  irregular  lateral  and  submedian  lines.  The  head  is  furnished  with  a  chiti- 
nous,  faintly  yellowish  "cuirasse,"  extending  back  to  opposite  the  base  of  the 
pharynx,  and  divided  longitudinally  into  six  lobes  by  as  many  sutures.  Each 
of  these  lobes  is  perforated  near  the  posterior  margin  by  two  oblique,  irregular 
locules,  each  a  little  more  than  half  as  long  as  the  amphids  are  wide.  The  three 
amalgamated  lips  are  nearly  obsolete.  Six  forward  pointing,  inconspicuous,  in- 
nervated papillae  form  a  single  circlet  on  the  front  of  the  head.  The  simple, 
rather  narrow,  more  or  less  irregularly  pyramidal,  well  chitinized  pharynx  is  as 
long  as  the  head  is  wide,  and  is  somewhat  narrowed  posteriorly,  where  the  two 
ventrally  submedian  oesophageal  glands  empty  into  it.  The  third  oesophageal 
gland,  ventral  in  position,  empties  into  the  lumen  of  the  oesophagus  a  little  more 
than  halfway  back  to  the  eye-spots.  When  shut  the  pharynx  rather  closely 
resembles  the  lumen  of  the  oesophagus,  which  possesses  a  well  developed  chiti- 
nous  lining.  The  only  armature  of  the  pharynx  is  the  dorsal,  labial,  two-lobed 
cordiform  piece  of  chitin  just  at  the  mouth  opening,  arranged  much  as  described 
by  Dr.  de  Man  for  Thoracostoma  antarcticum,  v.  Linst.  Two  faint  refractive  lines 
close  together  lead  backward  from  the  posterior  part  of  each  amphid.  The  two 
rather  widely  separated  eye-spots  are  located  at  a  distance  from  the  anterior 
extremity  equal  to  four  times  the  width  of  the  head,  and  are  one-sixth  as  wide 
as  the  corresponding  part  of  the  neck,  and  about  as  long  as  wide.  These  are 
somewhat  heart  shaped,  and  are  composed  of  compactly  arranged  brownish 
granules.  There  are  obscure  indications  of  a  refractive  body,  or  "lens,"  in  the 
hollowed  out  front  part  of  each  eye-spot.  The  conoid  oesophagus  is  about  half 
as  wide  as  the  neck,  and  presents  a  faint,  elongated  pharyngeal  swelling.  The 
cylindroid  cardia  is  one-fifth  to  one-fourth  as  wide  as  the  base  of  the  neck.  The 
thick-walled  intestine,  separated  from  the  oesophagus  by  a  collum  one-third  as 
wide  as  the  base  of  the  neck,  becomes  at  once  three-fifths  as  wide  as  the  body, 
and  is  about  six  cells  in  girth.  The  intestinal  cells  contain  numerous  uniform, 
colorless  granules.  The  posterior  lip  of  the  anus  is  slightly  elevated. 

The  hemispherical-conoid  to  convex-conoid  tail  tapers  from  the  anus  and 
ends  in  a  very  broad,  bluntly  rounded  terminus.  The  spinneret  is  a  very  slightly 
depressed  pore  with  a  suggestion  of  yellowish  color,  arranged  a  little  unsymmetri- 
cally,  so  that  it  empties  somewhat  toward  the  ventral  side,  and  not  axially.  It 


32  AXTARCTIC   MARINE 

is  unarmed,  though  a  little  in  front  of  it  there  are  a  very  few  papilla-like  setae. 
The  three  more  or  less  elongated  saccate  caudal  glands  extend  in  a  loose  tandem 
in  front  of  the  anus  a  distance  five  times  as  great  as  the  corresponding  body- 
diameter.  Their  distinct  and  somewhat  tortuous  ducts  widen  to  three  separate 
ampullae  so  as  to  fill  the  middle  of  the  tail.  The  vulva  is  slightly  depressed  and 
is  rather  inconspicuous.  The  vagina  extends  inward  at  right  angles  to  the  ven- 
tral surface  about  halfway  across  the  body.  Both  before  and  behind  the  vulva 
there  are  well  developed  unicellular  glands.  Each  of  the  two  straight  uteri  is 
about  seven  times  as  long  as  the  body  is  wide,  and  contains  a  row  of  five  or  six 
eggs  in  the  specimens  examined.  The  rather  thick-shelled  eggs  are  three-fourths 
as  long  as  the  body  is  wide,  and  nearly  as  wide  as  long.  Owing  to  their  pressure 
on  each  other  the  eggs  take  on  a  more  or  less  rectangular  contour.  The  broad  ova- 
ries reach  two-thirds  the  way  back  to  the  vulva,  and  contain  scores  of  discoid 
ova,  arranged  more  or  less  in  single  file. 

The  anus  of  the  male  is  broadly  elevated.  The  tail  of  the  male  has  a  compli- 
cated sexual  armature.  Near  the  anus  on  the  anterior  fourth  of  the  tail  there 
are  six  stout,  stiff,  conoid,  somewhat  blunt,  ventrally  submedian  setae  on  each 
side,  the  longest  of  which,  those  nearest  the  anus,  are  nearly  as  long  as  the  cuti- 
cle is  thick,  and  the  smallest  of  which,  the  hindermost,  are  very  small.  The  pre- 
anal  setae  are  arranged  in  ventrally  submedian  rows,  of  which  the  individual 
setae  are  much  nearer  together  posteriorly  than  anteriorly.  Between  the  anus 
and  the  single  ventral  median  supplementary  organ  there  are  ten  of  these  setae; 
between  the  latter  and  the  posterior  member  of  the  ventrally  submedian  rows 
of  supplementary  organs  there  are  two  of  these  setae;  between  the  ultimate  and 
the  penultimate  members  of  the  submedian  series  there  are  also  two.  Thence 
forward  between  any  two  members  of  the  submedian  series  there  is  but  a  single 
seta.  In  all,  therefore,  there  are  about  seventeen  of  these  setae  on  each  submedi- 
an line  in  front  of  the  anus.  In  addition  there  are  two  very  inconspicuous,  papil- 
loid,  tapering,  acute,  lateral  setae  near  the  terminus.  The  lateral  fields,  one-third 
to  two-fifths  as  wide  as  the  body,  are  composed  of  several  rows  of  cells  among 
which  are  placed  glandular,  saccate  cells,  of  two  or  three  times  as  great  diameter, 
connected  with  the  exterior  by  means  of  pores  in  the  cuticle.  The  relative  num- 
ber and  position  of  these  glandular  cells  may  be  judged  to  a  certain  extent  from 
the  fact  that  in  the  female  near  the  vulva  three  of  these  large  saccate  cells  are 
separated  from  each  other  by  spaces  about  equal  to  their  own  diameter.  These 
cells  are  entirely  similar  to  those  described  by  Jaegerskiold,  de  Man,  and  other 
authors,  who  have  made  observations  on  species  of  Thoracostoma.  The  distinct 
cells  connected  with  the  more  or  less  broad  and  oblique  nerve-ring  are  arranged 
into  rather  distinct  groups  and  are  a  prominent  feature  of  the  middle  half  of  the 
neck. 

The  stout,  blunt,  yellowish  spicula,  cephalated  by  a  very  slight  constriction, 
are  arcuate  in  the  distal  half,  and  are  one  and  three-fourths  times  as  long  as  the 
anal  body-diameter.  At  the  widest  part,  a  little  in  front  of  the  middle,  they 
are  about  one-fourth  as  wide  as  the  corresponding  part  of  the  body.  From  the 
widest  part  they  taper  gradually  to  the  distal  ends,  but  taper  more  suddenly 
toward  the  proximal  ends,  which  lie  opposite  the  body-axis  and  have  a  width 
when  viewed  in  profile  about  twice  as  great  as  the  thickness  of  the  adjacent  cuti- 
cle on  the  dorsal  side  of  the  body.  The  difference  between  the  anterior  and  pos- 


FREE-LIVING   NEMATODES  33 

terior  parts  of  the  spicula  is  greater  than  in  Thoracostoma  setosum,  Linst.  The 
strong,  chitinous  framework  is  strengthened  by  a  middle  piece  in  the  distal  three- 
fifths.  The  two  separate,  strong,  rather  stout  accessory  pieces  are  bent  a  very 
little,  and  are  half  as  long  as  the  spicula.  They  are  of  somewhat  irregular  width, 
but  appear  when  seen  in  profile  about  twice  as  wide  as  the  dorsal  cuticle  is  thick. 
They  lie  parallel  to  the  spicula,  but  their  cephalated  proximal  ends,  a  little  wider 
than  those  of  the  spicula,  are  bent  away  a  little  and  lie  somewhat  to  the  dorsal  side 
of  the  body-axis. 

The  elevated,  mammiform  supplementary  organs,  about  one-sixth  as  wide 
as  the  body  and  half  as  high  as  wide,  are  arranged  in  ventrally  submedian  rows 
one  and  two-thirds  times  as  long  as  the  body  is  wide,  the  posterior  members  being 
located  a  distance  in  front  of  the  anus  equal  to  one  and  two-thirds  times  the  length 
of  the  spicula.  They  are  a  little  farther  apart  posteriorly  than  anteriorly,  the 
longest  space  being  about  equal  to  the  length  of  the  radius  of  the  body  as  seen 
in  profile  at  the  corresponding  part.  In  addition  to  these  two  rows  of  five  organs 
each  there  is  a  single  ventral  organ  a  little  in  front  of  the  middle  of  the  spiciila, 
similar  in  size  and  form  to  the  others,  but  manifestly  of  a  different  structure. 
Sometimes  there  is  an  appearance  as  if  a  rudimentary  sixth  ventrally  submedian 
organ  is  present  in  front  of  the  fifth.  Oblique  copulatory  muscles  are  arranged 
close  together  coextensive  with  the  supplementary  organs.  The  ejaculatory 
duct  is  about  one-fifth  as  wide  as  the  corresponding  part  of  the  body. 

Habitat;  remarks.  Bay,  Cape  Royds;  Cape  Royds.  Three  females  and  two 
males,  in  good  condition. 


February,  1914. 


NORTH  AMERICAN 

FREE-LIVING  FRESH-WATER 
NEMATODES 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY 

II 

BY  N.  A.  COBB 
(With   eighty  illustrations) 


INTRODUCTION. 

The  little  creatures  described  in  these  pages  belong  to  a  very 
important  but  as  yet  comparatively  little  known  class  of  animal 
organisms,  the  nematodes. 

Something  more  than  a  mere  reconnaissance  leads  to  the  con- 
clusion that  over  nine-tenths  of  the  nematode  species  still  remain 
unknown,  a  greater  disproportion  between  the  known  and  the  un- 
known than  exists  in  almost  any  other  class  of  organisms. 

Nematodes  are  distributed  far  and  wide  in  inconceivable  num- 
bers, and  without  doubt  constitute  a  group  in  the  animal  kingdom 
comparable  with  insects  both  in  number  of  species  and  economic 
importance.  They  vary  in  length  from  one  two-hundredth  of  an  inch 
to  several  feet,  though  the  great  majority  are  less  than  half  an  inch 
long.  They  differ  from  most  other  slender,  wormlike  forms  in 
their  lack  of  locomotive  appendages, — the  outer  surface,  except  for 
the  presence  of  setae,  is  usually  quite  smooth.  Being  more  or  less 
cylindrical  in  form,  they  are  often  called  "round-worms."  They 
live  free  in  the  soil,  in  fresh  and  salt  water,  and  are  found  parasitic 
in  a  great  variety  of  animals  and  plants. 

NEMATODES  AS   CAUSES  OF  DISEASE 

The  parasitic  species  often  cause  fatal  diseases  of  plants  and 
of  animals,  including  mankind.  The  dreaded  hookworm  is  a  nema- 
tode. So  is  that  scourge  of  the  tropics,  the  guinea  worm.  Trichina,* 


"Trichinella  spiralis. 


Reprinted  from  Trans.  American  Microscopical  Society.     Vol.  XXXIII,  April,  1914. 


36  NORTH   AMERICAN 

costing  civilized  nations  hundreds  of  thousands  of  dollars  yearly 
for  the  inspection  of  pork,  is  a  nematode.  If  trichina,-infested  or 
measly  pork  be  eaten  by  human  beings,  the  result  is  a  serious,  often- 
times fatal,  sickness,  called  trichinosis,  epidemics  of  which  have 
claimed  victims  by  the  hundred.  Nematodes  have  recently  been 
suspected,  with  good  show  of  reason,  of  being  carriers  of  cancer. 
So  the  list  of  serious  human  nematode  diseases  might  be  increased 
until  practically  half  a  hundred  had  been  enumerated. 

No  less  serious  are  the  nematode  diseases  of  plants  and  of 
the  lower  animals.  The  common  gall-worm  has  been  found  infest- 
ing the  roots  of  several  hundred  different  species  of  plants,  among 
them  most  of  our  cultivated  crops,  and  causes  a'n  annual  loss 
amounting  to  millions  of  dollars.  There  is  another  nematode  that 
has  at  times  completely  checked  the  growing  of  sugar  beets  in  cer- 
tain regions.  The  list  of  serious  plant  diseases  of  this  character 
could  easily  be  increased  to  scores.  The  same  is  true  of  animals. 
Every  domestic,  doubtless  every  wild,  species  has  a  number  of 
specific  nematode  parasites  sapping  its  vitality. 

WONDERFUL   VARIETY   OF   HABITAT. 

Not  the  least  interesting  thing  about  nematodes  is  the  astound- 
ing variety  of  their  habitats.  They  occur  in  arid  deserts  and  at  the 
bottoms  of  lakes  and  rivers,  in  the  waters  of  hot  springs  and  in 
polar  seas  where  the  temperature  is  constantly  below  the  freezing 
point  of  pure  water.  They  were  thawed  out  alive  from  Antarctic 
ice  in  the  far  south  by  members  of  the  Shackelton  expedition.  They 
occur  at  enormous  depths  in  Alpine  lakes  and  in  the  ocean.  As 
parasites  of  fishes  they  traverse  the  seas ;  as  parasites  of  birds  they 
float  across  continents  and  over  high  mountain  ranges.  Their  eggs 
and  larvae,  invariably  of  microscopic  size,  are  carried  from  place  to 
place  by  an  exceedingly  great  variety  of  agencies.  Almost  any  vis- 
ible thing  that  moves  is  capable  of  transporting  nematode  eggs  or 
larvae.  Sometimes  the  eggs  and  larvae  are  so  resistant  to  dryness 
that  if  converted  to  dust  they  revive  when  moistened.  This 
revival  of  mummified  nematodes  may  take  place  after  as  long  a 
period  as  a  quarter  of  a  century. 

Nematodes  are  found  in  queer  places.  The  wildest  imagina- 
tion could  hardly  outpicture  the  facts.  One  species  is  found  prac- 


FREE-LIVING   FRESH-WATER    NEMATODES  37 

tically  only  in  the  vermiform  appendix  of  man;  another  has  its 
adult  form  only,  in  the  seeds  of  wheat.  A  third  form  occurs  in 
the  felt  mats  on  which  the  Germans  are  accustomed  to  set  their 
mugs  of  beer,  and  has  been  found  in  no  other  habitat.  On  the  feet 
of  birds  and  insects  the  eggs,  larvae,  and  adults  of  certain  nema- 
todes  are  carried  to  the  tops  of  the  tallest  trees.  The  sour  sap  is- 
suing from  the  wounds  of  a  tree,  often  many  feet  above  the  ground, 
not  infrequently  contains  nematodes  that  are  specific  to  the  wounds 
of  that  particular  kind  of  tree.  The  tap  water  of  even  well-con- 
ducted cities  often  contains  nematodes. 

Nematodes  are  inconceivably  abundant.  A  thimbleful  of  mud 
from  the  bottom  of  the  ocean  may  contain  hundreds  of  specimens. 
The  number  of  nematodes  in  the  top  six  inches  of  an  acre  of  ordi- 
nary arable  soil  amounts  to  thousands  of  millions.  Statistical  cal- 
culations relative  to  the  number  of  nematodes  in  a  single  acre  of 
soil  near  San  Antonio,  Texas,  U.  S.  A.,  disclosed  that  if  they  could 
start  in  a  procession  for  Washington,  D.  C.,  two  thousand  miles 
away,  each  close  on  the  tail  of  the  one  in  front,  the  head  of  the 
procession  would  reach  Washington  before  the  rear  had  left  San 
Antonio.  As  nematodes  are  usually  very  prolific,  a  single  female 
sometimes  producing  thousands  of  eggs,  the  number  of  eggs  vastly 
exceeds  that  of  the  adults". 

We  must  therefore  conceive  of  nematodes  and  their  eggs  as 
being  carried  by  the  wind,  and  by  flying  birds  and  running  animals ; 
as  floating  from  place  to  place  in  nearly  all  the  waters  of  the  earth ; 
and  as  shipped  from  point  to  point  throughout  the  civilized  world 
in  vehicles  of  traffic. 

There  are  beneficial  nematodes,  though  knowledge  of  this  phase 
of  the  subject  is  in  its  earliest  infancy.  Some  nematodes  feed  ex- 
clusively on  their  injurious  brethren.  Others  devour  baneful  micro- 
organisms. Their  adaptations  and  relationships  appear  to  be  sim- 
ilar to  those  of  insects. 

NORTH   AMERICAN   FRESH-WATER   SPECIES. 

The  nematodes  here  described  are  the  main  portion  of  those 
found  during  a  rather  casual  search  for  aquatic  species  that  would 
serve  as  the  basis  of  a  special  chapter  in  a  zoological  textbook  de- 
voted to  fresh  water  organisms.  The  object  of  the  textbook  was 


287184 


38  NORTH    AMERICAN 

to  characterize  each  known  genus  by  describing  and  illustrating  a 
typical  species. 

When  the  work  on  the  nematode  chapter  was  begun  there  was 
hardly  a  single  adequately  described  North  American  species,  so 
that  the  initial  task  was  one  of  pure  discovery.  This  was  followed 
by  the  work  of  research  and  definition,  and  this  finally  by  that  of 
selection  and  presentation  of  typical  species  in  a  manner  suitable 
to  a  college  textbook. 

The  famous  Philadelphian,  Dr.  Joseph  Leidy,  appears  to  be 
the  only  naturalist  who  had  previously  attempted  to  describe  any  of 
our  fresh  water  nematodes,  and  even  he  did  but  little.  I  have  at- 
tempted to  rehabilitate  his  Anguilhda  longa,  which,  as  Bastian  sur- 
mised, belongs  to  the  more  modern  genus  Trilobus.  I  have  had  to 
assume  that  the  variety  Leidy  had  before  him  was  that  most  com- 
mon in  the  ditches,  brooks  and  rivers  of  the  Chesapeake  region, 
and  have  given  to  this  form  the  name  Trilobus  longus  (Leidy) 
Bastian. 

All  the  other  species  proved  to  be  new,  some  of  them  repre- 
sentatives of  new  genera.  Most  of  the  new  genera  have  already 
been  described  in  my  contribution  to  the  Proceedings  of  the  Wash- 
ington Academy  of  Sciences,  October,  1913. 

An  aquatic  species  as  here  defined  is  any  species  inhabiting 
either  fresh  water,  or  non-brackish  swampy  soil  below  the  water 
table ;  hence  a  species  that  will  not  drown  in  fresh  water ;  a  species 
fitted  to  utilize  oxygen  dissolved  in  fresh  water. 

Including  those  of  the  present  article,  the  fresh  water  North 
American  species  so  far  described  are  as  follows : 
Achromadora  minima  Cyatholaimus  truncatus 

Actinolaimus  radiatus  Diplogaster  fictor,  Bastian 

Alaimus  simplex  Dolichodorus  heterocephalus 

Anonchus  monhystera  Dorylaimus  fecundus 

Aphanolaimus  minor  Ethmolaimus  americanus 

Aphanolaimus  spirurus  Iota  octangulare 

Bastiana  exilis  Ironus  americanus 

Cephalobus  setosus  Mesomermis  virginiana 

Cephalobus  subelongatus  Microlaimus  fluviatilis 

Chronogaster  gracilis  Monhystera  sentiens 

Cryptonchus  nudus  Mononchus  similis 


FREE-LIVING    FRESH-WATER    NEMATODES 


39 


Oncholaimus  punctatus  Spilophora  canadensis 

Plectus  tubifer  Teratocephalus  cornutus 

Prismatolaimus  stenurus  Trilobus  longus  (Leidy),  Ba'stian 

Rhabditis  punctatus  Tripyla  lata 

Rhabdolaimus  minor  Tylcnchus  symmetricus 

There  has  been  little  time  or  opportunity  to  search  specially  for 
these  fresh  water  forms,  and  the  fact  that  it  has  been  possible  in  so 
short  a  time  to  assemble  so  many  genera  and  species  is  proof  of 
the  enormous  abundance  and  multifarious  nature  of  these  organ- 
isms. No  doubt  there  is  a  horde  of  species  awaiting  discovery  in 
North  American  waters. 

THE  NEMATODE  FORMULA. 

The  following  diagram  illustrates  the  nature  of  the  formula 
used  in  the  tabulation  of  the  various  necessary  measurements : 
=?#; 


Fig.  1.  Diagram  of  the  descriptive  decimal  formula  used  for  nematodes;  6,  7,  8,  10, 
6  are  the  transverse  measurements,  while  7,  14,  28,  50,  88  are  the  corresponding  longi- 
tudinal measurements.  The  formula  in  this  case  is: 

7.     14.     28.     SO.     88. 


6.       7.       8.     10.       6. 

The  unit  of  measurement  is  the  hundreth  part  of  the  length 
of  the  body,  whatever  that  may  be.  The  measurements  become, 
therefore,  percentages  of  the  length.  The  absolute  length  is  given 
in  millimeters  as  a  final  non-paired  term.  This  decimal  method  of 
presenting  the  measurements  is  the  most  compact  and  convenient 
method,  and  is  being  used  more  and  more  year  by  year. 

The  measurements  are  taken  with  the  animal  viewed  in  profile ; 
the  first  are  taken  at  the  base  of  the  pharynx,  the  second  at  the 
nerve-ring,  the  third  at  the  cardiac  constriction  or  end  of  the  neck, 
the  fourth  at  the  vulva  in  females  and  at  the  middle  (M)  in  males, 
the  fifth  at  the  anus.  The  formulae  represent  the  average  of  sev- 
eral specimens  whenever  possible. 

There  are  several  methods  of  securing  the  measurements,  one 
of  the  most  convenient  being  the  preparation  of  a  camera  lucida 
"skeleton"  to  scale,  consisting  of  a  line  following  the  body  axis 


4O  NORTH    AMERICAN 

from  one  end  to  the  other,  and  diametral  lines  at  the  base  of  the 
pharynx,  the  nerve-ring,  the  end  of  the  neck,  at  the  vulva  in  fe- 
males and  at  the  middle  in  males,  and  finally  at  the  anus.  This 
skeleton  is  then  measured  with  a  metric  scale  and  map  measure, 
and  the  percentages  divided  out  with  the  aid  of  a  slide  rule. 

IOTA,  Cobb,  1913. 

Fig.  1,  Plate  II. 

57 

14.      21.      25.      -85      Q2. 

1.     Iota  octangulare,  n.sp.  .4  mm. 

II.      12.      12.         9.          6. 

Along  the  longitudinal  fields  the  striae  are  so  modified  as  to  give  the 
worm  somewhat  the  appearance  of  being  covered  by  eight  rows  of  relatively 
large  scales  arranged  in  pairs.  Six  small,  simple,  flattish  lips  surround  the 
vestibule.  The  lips  are  supplied  with  six  small,  innervated  papillae.  These 
lie  in  the  midst  of  a  plate-shaped  disk,  the  first  annule.  There  are  no  recog- 
nized traces  of  amphids,  but  the  recessive  nature  of  the  second  annule  is 
suggestive,  and  it  is  possible  that  this  peculiarity  of  the  second  annule  is  in 
some  way  connected  with  the  amphids.  There  are  no  eye-spots.  The  narrow 
vestibule  leads  to  the  equally  narrow  pharynx,  which  consists  essentially  of 
a  muscular  tube  closely  surrounding  the  spear.  This  latter  is  of  relatively 
very  large  size,  and  strictly  Tylenchoid  in  structure.  Its  length  is  about 
equivalent  to  the  first  twelve  annules  of  the  cuticle.  It  is  divisible  into  two 
parts :  a  long  cylindrical  hollow  shaft  tapering  to  a  point  near  its  apex,  and 
having  a  length  about  equivalent  to  the  first  nine  annules ;  behind  this  shaft 
a  basal  portion  or  "hilt,"  which  in  its  distal  part  has  a  structure  like  that 
of  the  shaft,  but  with  a  slightly  greater  diameter.  This  hilt  terminates  in  a 
threefold,  flattish  bulb  about  one-fourth  as  wide  as  the  corresponding  por- 
tion of  the  neck.  The  lumen  of  the  spear  is  continuous  with  that  of  the 
oesophagus.  This  latter  consists  mainly  of  a  narrow,  chitinous  tube,  which 
is  usually  somewhat  coiled  when  the  spear  is  at  rest.  That  portion  of  the 
oesophagus  containing  the  hilt  of  the  spear  and  the  coiled  oesophageal  tube 
just  mentioned  constitutes  a  somewhat  obscure  elongated  "bulb."  This  bulb, 
however,  is  not  the  morphological  equivalent  of  the  bulb  usually  seen  in  the 
oesophagus  of  Tylenchus  and  Aphelenchus,  as  it  has  no  radial  muscles,  and 
contains  no  valvular  apparatus.  The  remaining  short  portion  of  the  oesopha- 
gus is  tubular  and  narrow,  though  it  swells  slightly  at  the  terminus,  where  it  is 
about  one-eighth  to  one-ninth  as  wide  as  the  base  of  the  neck.  The  ex- 
cretory pore  empties  through  the  exterior  margin  of  the  nineteenth  annule, 
or  thereabouts.  It  may  be  distinctly  seen  when  the  worm  is  viewed  from 
the  ventral  side,  and  less  distinctly  seen  in  profile. 

Habitat:     Dismal  Swamp,  Va.     Flemming  solution  to  glycerine. 


FREE-LIVING   FRESH-WATER   NEMATODES  41 

RHABDOLAIMUS,  de  Man,  1880. 
Fig.  2,  Plate   II. 

28 

2.     Rhabdolaimus  minor,  n.sp.     4'6     *5' ^ <5I>     77'5      28  mm 

2.4      37      3-8       4-       2. 

The  thin  layers  of  the  transparent,  naked,  colorless  cuticle  appear  to  be 
destitute  of  any  but  very  fine  transverse  striations,  most  clearly  visible  near  the 
head.  The  conoid  neck  ends  in  a  rounded  head  which  is  not  set  off  in  any 
way.  There  are  no  cephalic  setae.  Careful  focussing  appears  to  indicate  on 
the  outer  margin  of  the  head  the  presence  of  almost  invisible  papilla-like  or- 
gans which  may  perhaps  be  representatives  of  cephalic  setae.  There  are  no 
lips.  The  amphids  are  located  at  a  distance  from  the  anterior  extremity 
about  three  times  as  great  as  the  width  of  the  lip-region,  and  a  little  more 
than  twice  as  great  as  the  width  of  the  head  near  where  they  occur.  Seen 
in  dorso-ventral  view  they  have  the  appearance  of  obscure  openings  from 
which  there  leads  inward  and  backward  slight  refractive  elements  which 
soon  become  indefinite.  Immediately  behind  the  mouth  opening  there  is  at 
least  one  obscure  refractive  element  of  small  size,  apparently  very  much  as 
figured  by  Dr.  de  Man  in  his  description  of  the  type  species.  The  tubular 
pharynx  is  long  and  slender,  extending  backward  for  a  considerable  distance 
behind  the  amphids.  Its  total  length  is  probably  a  little  less  than  one-third 
the  distance  to  the  nerve-ring,  though  the  limits  are  not  definite  in  the  speci- 
mens so  far  examined.  The  oesophagus  is  at  first  about  three-fourths  as 
wide  as  the  head  and  continues  to  have  this  diameter,  or  a  slightly  greater 
diameter,  until  near  the  end,  where  it  expands  to  form  the  pyriform  cardiac 
bulb  which  contains  an  obscure  valvular  apparatus.  This  bulb  is  three- 
fourths  as  wide  as  the  base  of  the  neck.  The  lining  of  the  oesophagus  may 
be  faintly  seen  throughout  its  length.  The  rather  thin-walled  intestine  which 
is  separated  from  the  oesophagus  by  a  slight  constriction  becomes  at  once 
three-fourths  as  wide  as  the  body.  It  appears  to  be  composed  of  cells  of 
such  size  that  probably  only  four  to  six  are  required  to  build  a  circumfer- 
ence. From  the  nearly  continuous  anus,  the  rectum,  which  is  somewhat 
longer  than  the  anal  body  diameter,  extends  inward  and  forward.  The  tail 
begins  to  taper  from  a  little  in  front  of  the  anus  and  tapers  regularly  to 
the  terminus  which  is  armed  with  a  striking,  elongated,  unarmed,  slightly 
tapering,  acute  spinneret.  Where  the  tail  joins  the  spinneret  the  diameter  is 
about  one-fifth  as  great  as  at  the  anus.  There  is  a  sudden  and  very  slight 
diminution  of  diameter  of  the  terminus  where  it  joins  the  spinneret.  From 
the  inconspicuous  vulva,  the  vagina  leads  inward  and  forward.  The  sym- 
metrically reflexed  ovaries  reach  about  half  way  back  to  the  vulva.  The 
thin-shelled,  smooth  eggs  are  relatively  large  and  elongated  and  have 
been  seen  in  the  uterus  one  at  a  time.  They  are  about  four  to  five 
times  as  long  as  the  body  is  wide  and  about  one-fifth  as  wide  as  long. 
They  appear  to  be  deposited  before  segmentation  begins. 

Habitat:  Mud,  Beach  pool,  Pine  Point,  Douglas  Lake,  Michigan. 
Sublimate  to  balsam. 


42  NORTH    AMERICAN 

DIPLOGASTER,   Max   Schultz,    1857. 

Fig.  3,  Plate  II. 

35 

1.3     10.7     13.8    '51'    88.1 

3.     Diplogaster  fictor,  Bastian  —  1.5  mm. 

1.3      1.4      1.4     1.7      1.4 

The  thin  layers  of  the  transparent,  colorless,  practically  naked  cuticle 
are  traversed  by  exceedingly  fine  transverse  striae,  resolvable  with  high 
powers  under  favorable  conditions,  which  become  considerably  coarser  to- 
ward the  head,  where  they  are  resolvable  into  rows  of  refractive  dots  ar- 
ranged in  longitudinal,  as  well  as  transverse  lines.  A  short  distance  behind 
the  head  the  longitudinal  rows  arrange  themselves  in  pairs.  These  pairs 
indicate  the  locus  of  about  twenty-four  cuticular  ribs  or  wings,  which  extend 
from  the  middle  of  the  neck  to  near  the  anus.  On  the  tail  these  ribs  again 
resolve  themselves  into  double  rows  of  dots,  and  gradually  disappear  as  the 
tail  grows  narrower.  Very  little  is  to  be  seen  of  them  behind  the  middle 
of  the  tail.  The  cylindroid  neck  ends  in  a  somewhat  rounded  head,  which 
bears  near  its  outer  margin  a  circlet  of  six  somewhat  forward-pointing, 
tapering  cephalic  setae,  each  about  one-third  as  long  as  the  head  is  wide. 
There  is  one  of  these  setae  on  each  submedian  line  and  one  on  each  lateral 
line.  Just  in  front  of  the  base  of  each  lateral  seta  a  minute  obscure  pore  or 
papilla  was  observed,  which  did  not  appear  to  exist  in  connection  with  the 
other  setae.  The  amphids,  though  only  faintly  visible,  are  of  relatively 
large  size.  Their  form  is  partly  indicated  by  a  lateral  area  on  which  the 
punctations  of  the  cuticle  are  absent.  This  is  a  somewhat  elliptical  area 
placed  transversely  on  the  side  of  the  head,  with  its  long  axis  at  right  angles 
to  the  lateral  line.  Its  length  is  equal  to  half  that  of  the  correspond- 
ing diameter  of  the  head.  Its  anterior  contour  is  more  definite  than  the 
posterior,  although  it  is  only  by  the  most  caerful  focusing  that  the  defintie 
line  of  contour  can  be  distinguished.  Through  the  middle  of  the  area,  how- 
ever, there  is  quite  a  distinct  arcuate  line,  with  its  convex  side  toward  the 
lips.  When  seen  dorso-ventrally  the  amphids  have  the  appearance  of 
distinct  oblique  openings,  leading  inward  and  backward.  When  the  mouth 
is  opened  and  the  lips  recurved  the  amphids  are  moved  forward  somewhat 
and  the  transverse  line  mentioned  becomes  more  strongly  curved  and  forms 
a  semi-circumference.  The  circular  mouth  opening  is  very  finely  striated  on 
the  inner  surface  of  the  lip  region.  These  striae  begin  on  the  inner  face  of 
the  lips  near  where  the  cuticular  wall  of  the  pharynx  first  appears.  They 
extend  backward  nearly  to  the  base  of  the  pharynx  and  end  in- 
definitely. In  front  of  this  finely  longitudinally  striated  area  the  transverse 
marginal  portion  of  the  lips  is  more  coarsely  divided  into  fourteen 
parts.  The  lips  are  capable  of  being  opened,  so  that  the  oral  aperture 
is  two-thirds  as  wide  as  the  head.  Under  such  circumstances  it  is  seen 
that  the  lip  region  is  flower-like  in  form  with  fourteen  recurved  seg- 
ments, the  distal  tapering  portion  of  each  of  which  is  plain  and 


FREE-LIVING   FRESH-WATER   NEMATODES  43 

transparent,  while  the  basal  portion  is  traversed  longitudinally  by  four  min- 
ute, refractive,  somewhat  beaded  longitudinal  striae.  The  pharynx  is  about 
as  deep  as  it  is  wide,  and  in  its  widest  part  is  a  little  more  than  half  as  wide 
as  the  front  of  the  head.  It  is  well  filled  at  the  base  with  the  two  cres- 
cent-shaped, pointed,  pharyngeal  teeth.  These  extend  inward  and 
then  forward,  their  points  being  close  to  the  body  axis.  The  front  contours 
of  the  teeth  are  incurved,  and  at  one  point  on  their  front  surface  they  are 
exceedingly  finely  striated.  Each  of  these  teeth  occupies  about  one-fourth 
of  the  width  of  the  head;  measured  in  the  longitudinal  direction  its  ex- 
treme limits  are  less  than  when  measured  transversely.  The  entire  length  of 
the  pharynx  is  probably  somewhat  greater  than  the  width  of  the  head, 
though  it  joins  the  lumen  of  the  oesophagus  in  such  an  indefinite  way 
that  it  is  sometimes  rather  difficult  to  say  where  the  pharynx  ceases  and  the 
true  oesophagus  begins.  The  portion  of  the  oesophagus  surrounding  the 
pharynx  is,  however,  distinctly,  though  slightly,  swollen,  so  that  it  is  proper 
to  speak  of  an  elongated  pharyngeal  bulb.  Just  at  the  base  of  the  phraynx 
this  bulb  is  two-thirds  as  wide  as  the  corresponding  portion  of  the  head.  At 
a  point  two  or  three  body  diameters  farther  back  it  is  only  about  half  as 
wide  as  the  corresponding  portion  of  the  neck;  thence  onward  it  expands 
a  very  little.  Near  the  middle  of  the  neck  the  oesophagus  expands  to  form 
the  elongated  muscular  median  bulb,  which  is  three-fourths  as  wide  as  the 
middle  of  the  neck.  Here  the  lining  is  more  strongly  developed,  and  occupies 
about  one-fourth  of  the  optical  longitudinal  section,  while  the  lining  of  the 
preceding  portion  of  the  oesophagus  occupies  not  more  than  one-fifth  to  one- 
sixth  of  the  diameter.  Behind  the  median  bulb  the  oesophagus  is  less  strongly 
developed.  The  lining  is  much  less  conspicuous  and  the  radial  muscular  fibers 
are  less  abundant.  At  first  this  posterior  portion  of  the  oesophagus  is  only 
about  one-fourth  as  wide  as  the  middle  of  the  neck.  It  expands  gradually 
until  near  the  end,  then  more  rapidly  so  as  to  form  an  elongated- 
clavate  swelling,  three-fourths  as  wide  as  the  base  of  the  neck.  The  lining 
of  this  portion  of  the  oesophagus  is  a  distinct  feature,  but  is  by  no  means  so 
strongly  developed  as  that  of  the  preceding  portions  of  the  eosophagus. 
There  is  a  well  developed  flattish  cardia,  half  as  wide  as  the  base  of  the 
neck.  The  intestine,  which  is  separated  from  the  oesophagus  by  a  distinct 
constriction,  becomes  at  once  about  three-fourths  as  wide  as  the  body.  Its 
cells  contain  scattered,  nearly  colorless  granules  of  variable  size,  the  largest 
of  which  have  a  diameter  nearly  equal  to  the  distance  between  two  of  the 
adjacent  longitudinal  striations.  From  the  slightly  depressed  anus  the  rec- 
tum, which  is  about  one  and  one-half  times  as  long  as  the  anal  body  diam- 
eter, extends  inward  and  forward.  The  tail  is  conoid  from  the  anus  and 
tapers  rather  regularly  to  the  extremely  fine,  hair-like  terminus.  There  are 
no  caudal  glands. 

From  the  rather  prominently  elevated  vulva  the  chitinized  vagina  leads 
inward  at  right  angles  to  the  ventral  surface  half  way  across  the  body,  where 
it  joins  the  two  symmetrically-placed  uteri.  The  reflexed  ovaries  reach 


44  NORTH    AMERICAN 

about  half  way  back  to  the  vulva  and  contain  six  to  ten  developing  ova  ar- 
ranged single  file.  The  thin-shelled  eggs,  which  are  deposited  before 
segmentation  begins,  are  fully  twice  as  long  as  the  body  is  wide  and 
about  one-third  as  wide  as  long,  and  occur  in  the  uteri  one  at  a  time. 
Full-grown  ova  are  ellipsoidal,  and  about  one  and  one-half  times  as  long 
as  the  body  is  wide  and  about  half  as  wide  as  long. 

55 
.9    12.3     15.5    -M    86.6 

i.o  mm. 
i.i       1.4      1.4       1.5     1.6 

The  tail  of  the  male  is  like  that  of  his  mate  in  form.  There  are  no  sup- 
plementary organs  in  front  of  the  anus.  The  special  male  papillae  charac- 
teristic of  this  genus  are  located  as  follows :  A  single  tapering,  ventrally 
submedian  papilla  a  little  in  front  of  the  proximal  ends  of  the  spicula,  and 
slightly  farther  back  a  lateral  pre-anal  papilla;  a  ventrally  submedian  papilla 
as  far  behind  the  anus  as  that  first  described  is  in  front  of  it ;  a  lateral  papilla 
twice  as  far  behind  the  anus  as  that  just  described ;  a  ventrally  submedian 
papilla  as  far  behind  that  just  described  as  the  latter  is  behind  the  previous 
post-anal  papilla;  between  the  two  ventrally  submedian  papillae  just  de- 
scribed a  group  of  minute  subventral  papillae ;  near  the  middle  of  the  tail, 
on  the  slender  part,  two  sublateral  papillae.  Most  of  these  papillae  are 
slender,  tapering,  and  one-third  to  one-half  as  long  as  the  anal  body  diame- 
ter. The  two  equal,  yellowish,  arcuate,  acute  spicula  are  about  one  and  one- 
fourth  times  as  long  as  the  anal  body  diameter.  They  taper  pretty  regu- 
larly from  near  the  proximal  ends,  where  they  are  one-fourth  as  wide  as 
the  corresponding  portion  of  the  body.  The  proximal  ends  diminish  sud- 
denly in  diameter,  and  are  then  cephalated  by  expansion.  Each  expansion  is 
a  rather  strongly  refractive,  more  or  less  bulbous  piece  of  chitin.  The  acces- 
sory piece  is  arcuate  and  about  one-third  as  long  as  the  spicula.  It  is  par- 
allel to  and  applied  closely  to  the  spicula.  Its  framework  consists  of  two 
distinct,  nearly  parallel  parts.  The  ejaculatory  duct  is  about  one-fourth  as 
wide  as  the  body.  The  blind  end  of  the  single  outstretched  testicle  lies  a 
little  farther  behind  the  base  of  the  neck  than  this  latter  is  behind  the  an- 
terior extremity. 

Habitat:  Spring.  Washington  Country  Club,  Chevy  Chase,  Md. 
Sublimate  to  balsam. 

PRISMATOLAIMUS,  de  Man,  1880. 
Fig.  4,  Plate  III. 

14 

4.     Prismatolaimus  sternus,  n.sp.  i.i  mm. 

1.2    1.5      1.9       1.9       1.5 

The  moderately  thin  layers  of  the  transparent,  colorless  cuticle  are  tra- 
versed by  about  550  transverse  striae,  resolvable  with  high  powers  into 
rows  of  minute  elements.  There  are  no  longitudinal  striations.  Scattered  on 


FREE-LIVING   FRESH-WATER   NEMATODES  45 

the  neck  and  body  there  are  a  few  hairs  arranged  at  right  angles  to  the 
surface.  These  generally  have  a  length  equal  to  the  width  of  two  to  three 
annules  of  the  cuticle.  The  cylindroid  neck  ends  in  a  somewhat  truncated 
head,  which  is  not  set  off  in  any  way.  On  the  outer  margin  of  the  head  at 
the  base  of  the  lips  there  is  a  circlet  of  ten  widely  spreading,  straight,  taper- 
ing cephalic  setae,  two  of  somewhat  unequal  size  on  each  submedian  line, 
and  one  on  each  lateral  line.  The  longest  of  these  setae  are  a  little  more 
than  half  as  long  as  the  head  is  wide.  For  two-thirds  of  their  length  they 
are  finger-shaped;  the  remaining  third  is  a  much  narrower  bristle.  The 
very  thin  lips  are  arched  over  the  prismoid  pharynx,  which  is  nearly  as  deep 
as  the  head  is  wide,  and  about  three-fifths  as  wide  as  the  head.  It  attains 
its  full  width  immediately  behind  the  lips,  and  continues  to  have  the  same 
width  to  the  end,  so  that  the  bottom  of  the  pharynx,  though  not  even,  ex- 
tends across  the  base  of  the  head  approximately  at  right  angles  to  the  body 
axis.  Where  the  lumen  of  the  oesophagus  joins  the  pharynx  there  is,  how- 
ever, a  slight  backward  extension  of  the  pharyngeal  cavity.  There  are  no 
eye-spots.  The  amphids  occur  in  the  form  of  somewhat  elongated  trans- 
verse markings  placed  transversely  on  the  neck  somewhat  farther  behind 
the  base  of  the  pharynx  than  this  latter  is  behind  the  anterior  extremity. 
Each  amphid  has  a  length  about  one-third  as  great  as  the  corresponding 
width  of  the  neck,  and  is  about  half  as  wide  as  long.  Behind  each  amphid, 
at  a  distance  equal  to  the  width  of  two  to  three  annules  of  the  cuticle,  there 
is  a  short  seta.  The  oesophagus  receives  the  base  of  the  pharynx,  and  is 
at  once  nearly  three-fourths  as  wide  as  the  head.  It  narrows  very  slightly 
in  diameter  as  it  passes  backward,  so  that  where  it  passes  through  the  nerve- 
ring  it  is  about  two-thirds  as  wide  as  the  neck.  It  continues  to  have  prac- 
tically the  same  diameter  to  near  the  end,  where  it  is  two-thirds  as  wide  as 
the  base  of  the  neck.  Immediately  in  front  of  the  intestine  there  is  a  small 
segment  of  the  oesophagus  which  is  set  off  by  a  constriction.  This 
portion  is  somewhat  spheroidal  in  form.  The  lining  of  the  oesophagus  is  a 
distinct  feature  throughout  its  length,  and  comes  into  view  in  the  optical 
section  as  a  single  refractive  line.  This  line  is  nowhere  materially  altered. 
There  is  no  distinct  cardia,  unless  the  above  mentioned  spheroidal  segment 
of  the  oesophagus  may  be  so  considered.  The  rather  thick  walled  intestine, 
which  is  set  off  from  the  oesophagus  by  a  distinct  constriction,  becomes  at 
once  about  two-thirds  as  wide  as  the  body,  and  is  composed  of  cells  of  such 
a  size  that  probably  about  four  are  required  to  build  a  circumference.  These 
cells  contain  numerous  granules  of  rather  uniform  size,  which  are  not  dis- 
posed so  as  to  give  rise  to  a  tessellation.  From  the  somewhat  continuous 
anus  the  rectum,  which  is  about  as  long  as  the  anal  body  diameter,  extends 
inward  and  forward.  The  tail  end  begins  to  taper  from  some  distance  in 
front  of  the  anus,  and  tapers  regularly  thereafter  throughout  the  anterior 
portion  of  the  tail.  The  posterior  portion  tapers  very  slightly,  and  has  a 
diameter  one  to  two  times  as  great  as  the  width  of  one  of  the  annules  of 
the  cuticle,  measured  near  the  anus.  Though  the  terminus  has  considerable 


46  NORTH    AMERICAN 

width  there  is  no  spinneret.  The  lateral  fields  are  about  one-third  as  wide 
as  the  body.  The  nerve-ring  surrounds  the  oesophagus  somewhat  squarely. 
On  the  dorsal  side,  a  little  behind  the  cardiac  constriction  there  is  a  body 
which  presses  the  intestine  a  little  to  one  side,  which  may  perhaps  be  the 
renette  cell.  This  body  has  a  length  as  great  as  the  corresponding  body  di- 
ameter, and  is  about  one-fourth  to  one-third  as  wide  as  long.  The  vulva  is 
somewhat  elevated,  and  from  it  the  vagina  extends  inward  at  right  angles  to 
the  ventral  surface  about  one-third  the  distance  across  the  body.  There  are 
two  symmetrically  disposed,  reflexed  ovaries,  the  blind  ends  of  which  lie 
near  the  vulva,  the  position  depending  to  a  considerable  extent  upon  the  de- 
velopment of  the  much  elongated  eggs.  The  ovaries  are  moved  backward 
and  forward  to  a  certain  extent  in  accordance  with  the  stage  of  develop- 
ment of  the  eggs.  The  eggs,  which  have  been  seen  in  the  uteri  one  at  a  time, 
are  much  elongated — four  or  five  times  as  long  as  the  body  is  wide — 
and  about  one-fifth  as  wide  as  long.  They  appear  to  be  deposited  before 
segmentation  begins. 

Habitat:  Roadside  pool,  Douglas  Lake,  Michigan.  Sublimate  to 
balsam. 

SPILOPHORA,  Bastian,  1865. 

Fig.  5,  Plate  III. 
5.     Spilophora  canadensis,  n.sp. 

The  thin,  transparent  layers  of  the  colorless,  practically  naked  cuticle 
are  traversed  by  750  transverse  striae,  resolvable  with  high  powers  into 
rows  of  dots,  which  at  the  lateral  wings  are  so  modified  as  to  give  rise  to 
two  distinct  longitudinal  rows  of  dots  of  larger  size.  Along  the  middle  of 
the  body  one  of  these  rows  is  more  pronounced  than  the  other.  Opposite 
the  base  of  the  neck  the  distance  between  these  two  longitudinal  rows  is 
about  four  times  as  great  as  the  distance  between  two  of  the  dot-like  ele- 
ments. There  are  no  eye-spots,  nor  have  any  distinct  traces  of  amphids  been 
seen.  If  the  latter  are  present  they  must  be  very  inconspicuous.  The  lips  are 
so  small  that  it  is  very  difficult  to  count  them,  but  there  appear  to  be  twelve, 
each  one  obscurely  conical.  There  are  no  very  marked  subdivisions  between 
these  lips,  so  that  the  shallow  cyathiform  anterior  portion  of  the  pharynx, 
(a,  Fig.  5)  which  is  about  half  as  wide  as  the  head  and  about  one-third  to 
one-half  as  deep  as  wide,  is  not  prominently  striated  radially  as  is  some- 
times the  case  in  this  and  related  genera.  From  the  slightly  depressed  vulva, 
the  vagina  leads  inward  at  right  angles  to  the  ventral  surface  about  half  way 
across  the  body,  where  it  joins  the  two  symmetrically-placed  uteri.  The  re- 
flexed  ovaries  reach  fully  half  way  back  to  the  vulva,  at  least  in  young  speci- 
mens such  as  have  been  examined,  and  contain  a  dozen  to  twenty  developing 
ova  arranged  in  more  or  less  double  file.  The  eggs  appear  to  be  elongated, 
somewhat  longer  than  the  body  is  wide  and  about  one-third  as  wide  as  long. 
It  is  possible,  however,  that  there  is  some  error  here  as  the  description  is 


FREE-LIVING    FRESH-WATER   NEMATODES  47 

derived  from  a  single  specimen  in  which  these  features  are  rather  obscure. 
The  reversal  in  the  striations  of  the  cuticle  is  plainly  to  be  seen  in  the  re- 
gion of  the  vulva,  and  its  location  is  indicated  by  a  slight  rise  in  the  contour. 
This  slight  elevation  extends  also  to  the  subcuticle. 
60 

.5    8.3     14.8    -M    88.4 

.7  mm. 

2.        4.3        4.7  5.       3.2 

The  wing  markings  on  the  anterior  part  of  the  tail  are  pronounced, 
but  on  the  posterior  part  much  less  so.  A  little  in  front  of  the 
anus  they  are  as  pronounced  as  they  are  at  the  base  of  the 
neck,  and  both  are  equally  visible,  and  the  structure  not  infrequently  re- 
sembles that  of  a  ladder  with  the  rungs  placed  close  together,  just  as  it  does 
on  the  neck.  The  lateral  fields  appear  to  be  about  one-third  as  wide  as  the 
body.  Near  the  middle  of  the  body  may  plainly  be  seen  the  location  where 
the  cuticle  reverses  its  structure.  Although  the  striations  are  minute  they 
present  the  same  character  as  in  species  where  the  striations  are  coarse,  and, 
upon  careful  examination,  can  be  seen  to  be  retrorse  in  opposite  directions 
on  the  two  halves  of  the  body. 

Habitat :     Fresh  water  ponds,  Cape  Breton  Island,  Dominion  of  Canada. 

MICROLAIMUS,  de  Man,  1880. 
Fig.  6,  Plate  III. 

27 

6.     Microlaimus  fluviatilis,  n.sp.    *-6    8-5     *5-5    V    85.          mm 

1-9    3-5      4-3     47      2.6 

The  thin  layers  of  the  transparent,  colorless,  naked  cuticle  are  traversed 
by  exceedingly  fine  transverse  striae,  which  are  resolvable  with  great  diffi- 
culty into  rows  of  dots,  and  are  not  modified  on  the  lateral  fields.  The 
conoid  neck  ends  in  a  rounded  head  set  off  by  an  almost  imperceptible  con- 
striction. On  the  outer  margin  of  the  head  there  is  a  circlet  of  four  sub- 
median,  slightly  tapering  cephalic  setae,  each  about  one-third  as  long  as  the 
head  is  wide.  The  vestibule  is  considerably  shorter  than  any  of  the  cephalic 
setae,  and  is  longitudinally  striated,  indicating,  no  doubt,  that  the  lips  can 
be  opened  outward  in  receiving  food.  These  longitudinal  striations  of  the 
vestibule  are  too  minute  to  be  counted,  but  there  are  apparently  about  twelve. 
The  circular  amphids  are  about  one-fourth  as  wide  as  the  corresponding 
portion  of  the  head,  and  are  located  at  a  distance  from  the  anterior  ex- 
tremity equal  to  one  and  one-half  times  the  diameter  of  the  front  of  the 
head.  There  are  no  eye-spots.  The  limits  of  the  pharynx  are  indicated  by 
a  slight  constriction  in  the  oesophagus.  The  base  of  the  pharynx  is  some- 
what more  than  halfway  back  to  the  amphids.  The  general  form  of  the 
pharynx  is  cylindroid  or  prismoid.  It  is  armed  with  minute  and  very  in- 
conspicuous, somewhat  •  inward  pointing  and  apparently  not  very  regular 
teeth  or  projections.  The  most  conspicuous  of  these  projections  are  two  just 
behind  the  base  of  the  lips,  one  dorsal  and  the  other  apparently  ventral,  and 


48  NORTH    AMERICAN 

a  third  at  the  base  of  the  pharynx  on  the  dorsal  side.  The  oesophagus  be- 
gins as  a  tube  about  half  as  wide  as  the  corresponding  portion  of  the  neck, 
and  continues  to  have  this  diameter  until  it  swells  to  form  the  pyriform 
cardiac  bulb,  which  is  about  three-fourths  as  wide  as  the  base  of  the  neck, 
and  contains  a  distinct  chitinized  threefold,  rather  simple,  valvular  apparatus, 
occupying  two-fifths  of  the  diameter  as  seen  in  longitudinal  section.  The 
musculature  of  the  bulb  is  divided  into  three  sections,  a  small  anterior  sec- 
tion, a  middle  and  a  posterior  section.  Of  these  two  latter  the  posterior  is 
slightly  the  smaller.  The  lining  of  the  oesophagus  is  a  fairly  distinct  feature 
throughout  its  length.  There  is  no  very  distinct  cardia.  The  intestine  joins 
the  middle  of  the  posterior  surface  of  the  cardiac  bulb,  and  is  there  one- 
fourth  as  wide  as  the  base  of  the  neck.  It  soon  expands  so  as  to  become 
about  two-thirds  as  wide  as  the  body.  It  is  rather  thick  walled,  and  is  com- 
posed of  rather  thick  cells  which  are  of  such  a  size  that  about  four  are  re- 
quired to  build  a  circumference.  These  cells  contain  minute  granules.  From 
the  anus  the  rectum,  which  is  considerably  longer  than  the  anal  body  diam- 
eter, extends  inward  and  forward.  The  tail  is  conoid,  and  tapers  from  the 
anus  toward  the  terminus,  which  is  conoid  and  has  a  diameter  one-third  as 
great  as  that  of  the  base  of  the  tail,  and  bears  a  blunt  convex-conoid  unarmed 
spinneret.  The  rather  small  caudal  glands  appear  to  be  located  in  the  an- 
terior third  of  the  tail.  The  lateral  fields  have  not  been  seen.  From  the 
inconspicuous  vulva  the  vagina  leads  inward  at  right  angles  to  the  ventral 
surface  to  the  single  or  double  uterus,  which  when  single  extends  forward. 
There  sometimes  appears  to  be  a  small  posterior  rudimentary  branch  to  the 
sexual  organs,  which  is  about  equal  in  length  to  the  corresponding  body 
diameter.  The  reflexed  ovary  reaches  about  halfway  back  to  the  vulva, 
and  contains  about  half  a  dozen  or  more  ova  arranged  somewhat  irregu- 
larly. The  eggs  appear  in  the  uterus  one  at  a  time.  They  are  smooth,  some- 
what thin-shelled,  and  are  about  twice  as  long  as  the  body  is  wide,  and  about 
one-third  as  wide  as  long.  They  appear  to  be  deposited  before  segmentation 
begins.  Specimens  with  one  ovary,  and  those  with  two,  appear  to  be  about 
equally  numerous ;  as  no  other  difference  has  been  detected,  they  are  in- 
cluded for  the  present  under  the  same  name  and  description.  The  renette 
cell  is  an  elongated  cell  located  a  short  distance  behind  the  base  of  the  neck. 
It  is  fully  as  long  as  the  body  is  wide,  and  about  one-fourth  as  wide  as  the 
body.  The  excretory  pore  appears  to  be  located  opposite  the  nerve-ring. 
The  nerve-ring  surrounds  the  oesophagus  somewhat  squarely. 
Habitat:  Maple  River,  Michigan.  Sublimate  to  balsam. 

TRIPYLA,  Bastian,   1865. 
Fig.  7,  Plate  III. 

49, 

--,.,,  LI     6.8    19.6    '54'    83.5 

7.     Tnpyla  lata,  n.sp. 2.4  mm. 

2.3    3-1      3-5     4-        3-2 

The  thick  layers  of  the  transparent,  colorless,  naked  cuticle  are  apparently 
traversed    by    about    250    transverse     striae,    which    are    not     further    re- 


FREE-LIVING   FRESH-WATER    NF.MATODES  49 

solvable.  In  the  lumen  of  the  pharynx  at  a  point  removed  from  the 
anterior  extremity  a  distance  a  little  greater  than  the  radius  of  the 
head,  there  is  a  minute  inward-pointing  dorsal  tooth,  having  a  length 
about  equal  to  the  width  of  one  of  the  annules  of  the  cuticle.  This 
and  other  matters  prove  that  the  pharynx,  although  not  readily  dis- 
tinguished, extends  backward  a  distance  about  equal  to  the  width  of 
the  head.  In  some  specimens  it  is  possible  to  see  a  distinct  transverse 
fold  in  the  lining  of  the  oesophageal  tube.  This  is  located  at  a  dis- 
tance from  the  anterior  extremity  about  equal  to  the  corresponding 
diameter  of  the  head,  and  undoubtedly  indicates  the  posterior  lim- 
its of  the  pharynx.  It  is  possible  that  the  tooth  just  mentioned  may  be  con- 
nected with  internal  glandular  structures  in  the  oesophagus,  as  the  interior 
of  the  dorsal  segment  of  the  oesophagus  at  this  point  is  usually  more  or 
less  different  in  structure  from  the  other  portions  and  does  not  seem  to  be 
made  up  entirely  of  muscular  fibers.  The  oesophagus  is  separated  from  the 
intestine  by  a  flattish,  pseudo-bulb.  The  bulb  is  separated  from  the  oesopha- 
gus on  one  side  and  the  intestine  on  the  other  by  deep  and  distinct  constric- 
tions. In  the  anterior  constriction  there  are  at  least  two  granular,  elongated 
cells  of  considerable  size.  The  nerve-ring  surrounds  the  oesophagus  rather 
squarely.  Nothing  definite  is  known  concerning  the  renette  or  the  excretory 
pore.  From  the  inconspicuous  vulva,  the  vagina  leads  inward  at  right 
angles  to  the  ventral  surface  fully  half  way  across  the  body,  where  it  joins 
the  two  symmetrically-placed  uteri.  The  reflexed  ovaries  reach  about  half 
way  back  to  the  vulva,  and  contain  a  dozen  to  twenty  developing  ova  ar- 
ranged somewhat  irregularly.  Both  in  front  of  and  behind  the  vulva  there 
are  unicellular  glands,  having  a  diameter  about  one-sixth  as  great  as  that 
of  the  body. 

50 

.7    6.8    19.3    -M-    82.8 

2.4  mm. 

2.1     3.2      3.9     4.8        4.1 

The  tail  of  the  male  is  like  that  of  the  female  except  that  the  anus 
is  slightly  raised.  In  front  of  the  anus  there  is  a  ventral  row  of  about 
twenty  innervated  supplementary  organs,  reaching  to  near  the  head. 
The  distance  between  two  consecutive  organs  is  about  equal  to  the  ra- 
dius of  the  body.  Each  of  these  appears  to  consist  of  a  nerve-ending 
which  penetrates  the  cuticle  and  forms  a  papilla,  around  which  there  is 
an  almost  imperceptible  elevation  having  a  width  about  equal  to  two  of 
the  annules  of  the  cuticle.  The  visibility  of  this  small  organ  is  quite  as 
much  due  to  the  alteration  in  the  body  wall  and  subcuticle  as  to  that  in 
the  cuticle.  There  are  no  supplementary  setae  or  papillae  either  in 
front  of  the  anus  or  behind  it.  The  two  equal,  slightly  arcuate,  uni- 
formly tapering,  acute  spicula  are  about  one  and  one-fourth  times  as 
long  as  the  anal  body  diameter.  Their  proximal  ends  are  not  cephal- 
ated,  though  the  wall  of  the  cuticle  is  very  slightly  thickened  at  that 
point.  The  spicula  taper  regularly  from  the  proximal  ends  to  the  rather 


50  NORTH    AMERICAN 

truncated  points.  There  are  obscure  accessory  pieces  lying  close  to  the 
surface  of  the  spicula  and  forming  a  double  groove  in  which  these  lat- 
ter slide.  The  ejaculatory  duct,  though  narrow  at  first,  soon  becomes 
nearly  half  as  wide  as  the  body.  There  are  two  slender,  outstretched 
testicles  extending  in  opposite  directions  from  near  the  middle  of  the 
body.  The  anterior  one  has  its  blind  end  about  as  far  behind  the  base 
of  the  neck  as  the  nerve-ring  is  in  front  of  it. 

Habitat :  Alpine  lakes,  Bald  Mountain,  Colorado.    Formalin  to  glycerine. 

TERATOCEPHALUS,  de  Man,  1876. 

Fig.  8,  Plate  IV. 

ii 

8.     Teratocephalus  cornutus,  n.sp.  — : : '- : —  .8  mm. 

i.i       i.o    1.8    1.9     i.i 

The  thin,  transparent  layers  of  the  colorless  naked  cuticle  are  traversed 
by  about  1500  transverse  striae,  resolvable  into  rows  of  minute  dots,  which 
are  modified  on  the  lateral  fields.  These  modifications  have  been  seen  in 
all  parts  of  the  body,  and  near  the  tail  consist  of  two  to  three  irregular 
longitudinal  rows  of  enlarged  dots.  The  posterior  portion  of  the  neck  ta- 
pers but  little.  The  anterior  portion  becomes  convex-conoid  toward  the  head, 
which  bears  a  lip  region  more  or  less  set  off  by  a  constriction  opposite  the 
base  of  the  spreading  cephalic  setae,  which  are  four  in  number  and 
submedian  in  position.  Each  seta  is  a  little  more  than  half  as  long  as  the 
head.  These  are  connected  with  a  refractive  six-ribbed  chitinous  dome-like 
framework,  which  extends  back  to  opposite  the  middle  of  the  pharynx.  The 
ribs  start  at  the  lip  region,  extend  backward,  and  then  join  each  other  oppo- 
site the  base  of  the  vestibule.  The  chitinous  refractive  elements  at  this  latter 
region  form  a  rather  distinctly  crenate  contour  around  the  head.  No 
other  setae  than  the  cephalic  setae  have  been  seen  in  any  part  of  the  body. 
The  lips  appear  to  be  rather  thin,  and  are  arched  together  over  the 
unarmed  pharynx,  which  is  somewhat  elongated  and  about  half  as  wide 
as  the  base  of  the  head.  While  it  is  somewhat  irregular  in  form  it 
is  approximately  prismoidal  or  cylindroid  and  nearly  as  deep  as  the 
head  is  wide.  Its  walls  are  not  very  strongly  chitinized,  but  more 
strongly  so  anteriorly  than  posteriorly.  The  oesophagus  receives  the 
base  of  the  pharynx,  and  soon  becomes  half  as  wide  as  the  base 
of  the  head.  In  the  anterior  portion  of  the  oesophagus,  a  short  distance  , 
behind  the  pharynx  are  three  slightly  arcuate,  refractive  elements,  corre- 
sponding somewhat  in  curvature  with  the  contour  of  the  front  end 
of  the  oesophagus.  These  resemble  to  a  certain  extent  the  refractive  ele- 
ments in  the  posterior  chamber  of  the  pharynx  of  Plectus.  In  the  present 
species  they  are  about  as  long  as  the  pharynx,  and  are  separated  a  dis- 
tance about  equal  to  one  body  width.  They  are  a  little  wider  and  more 
plainly  visible  anteriorly  than  posteriorly.  The  obscure  amphids,  as 


FREE-LIVING   FRESH-WATER  NEMATODES  51 

far  behind  the  base  of  the  pharynx  as  this  latter  is  behind  the  anterior 
extremity,  are  one  third  as  wide  as  the  corresponding  part  of  the  head, 
and  consist  of  obscure  spirals  of  one  wind.  There  are  no  eye-spots. 
The  oesophagus  begins  as  a  tube  about  half  as  wide  as  the  correspond- 
ing portion  of  the  head,  but  expands  very  slightly  as  it  passes  back- 
ward, so  that  at  the  middle  it  is  about  two-thirds  as  wide  as  the 
middle  of  the  neck.  Behind  this  point  it  diminishes.  There  is  a 
break  in  the  musculature  somewhat  similar  to  that  occurring  in  Cephalobus. 
At  the  break,  which  occurs  at  the  beginning  of  the  fourth  fifth,  the 
oesophagus  is  somewhat  narrow,  about  half  as  wide  as  the  corre- 
sponding portion  of  the  neck.  It  finally  expands  to  form  the  ellipsoidal 
cardiac  bulb,  which  has  a  relatively  large,  chitinous,  striated,  complicated, 
three-fold  valvular  apparatus  half  as  wide  as  itself.  There  is  a  truncate- 
conoid  cardia  about  one-third  as  wide  as  the  base  of  the  neck.  The  lining 
of  the  oesophagus  is  a  fairly  distinct  feature.  The  thick-walled  intestine, 
which  is  separated  from  the  oesophagus  by  a  constriction,  soon  becomes  two- 
thirds  as  wide  as  the  body.  It  is  composed  of  cells  of  such  a  size  that  four 
are  required  to  build  a  circumference.  The  walls  of  these  cells  are  refrac- 
tive, so  that  the  cells  are  readily  distinguished  from  each  other,  though  there 
is  no  distinct  tessellation.  These  cells  contain  minute  very  uniform  granules. 
The  lining  of  the  intestine  is  refractive,  so  that  the  lumen  is  distinctly  to  be 
seen.  From  the  rather  inconspicuous  anus  the  rectum,  which  is  about  as 
long  as  the  anal  body  diameter,  extends  inward  and  forward.  The  internal 
sexual  organs  are  double  and  symmetrically  reflexed.  The  tail  is  conoid 
from  the  anus  to  the  subacute  terminus.  This  species  is  related  to  those 
described  by  Dr.  de  Man  under  the  name  of  Teratocephalus.  It  is  doubtful 
whether  these  forms  will  not  have  to  be  subdivided  at  some  future  time, 
after  the  accumulation  of  the  necessary  data. 

Habitat:     Maple  River,   Michigan.     Sublimate  to  balsam. 

ALAIMUS,  de  Man,  1880. 
Fig.  9,  Plate  IV. 


.2    ii.     19-    35-     92. 
9.     Alaimus  simplex,  n.sp. 


.3  .8  .9  i.i  -6 
The  thin,  transparent  layers  of  the  colorless,  naked  cuticle  would  ordi- 
narily be  described  as  destitute  of  striations.  Very  minute  striations  may 
be  observed  in  the  subcuticle  at  the  extremities,  when  the  specimens  are  ex- 
amined under  favorable  conditions  with  the  highest  powers.  There  are 
obscure  traces  of  lateral  wings.  The  conoid  neck  ends  in  a  rounded  head 
not  set  off  in  any  way.  There  are  no  distinct  lips,  and  only  the  faintest 
possible  indications  of  labial  papillae.  These  are  so  obscure  that  it  has  been 
found  impossible  to  enumerate  them.  There  is  no  pharynx  and  the  mouth 
opening  is  exceedingly  minute.  No  amphids  or  eye-spots  have  been  seen. 


52  NORTH    AMERICAN 

The  oesophagus  begins  at  the  lip  region  as  a  tube  two-thirds  as  wide  as  the 
head,  and  expands  gradually  and  rather  regularly  to  the  end,  where  it  has 
a  diameter  three-fourths  as  great  as  that  of  the  neck.  A  short  distance  be- 
hind the  head  end,  a  distance  six  times  as  great  as  the  diameter  of  the  head, 
there  is  a  slight  alteration  in  the  structure  of  the  oesophagus  the  significance 
of  which  remains  doubtful.  The  lining  of  the  oesohpagus  is  not  a  very  dis- 
tinct feature.  There  is  a  very  obscure,  small  cardia.  The  intestine,  which 
is  separated  from  the  oesophagus  by  a  constriction,  becomes  at  once  about 
two-thirds  to  three-fourths  as  wide  as  the  body.  At  first  its  cells  contain 
but  few  scattered  granules,  but  soon  they  are  characterized  by  the  presence 
in  them  of  loosely  scattered  yellowish-brown  granules  of  variable  size,  the 
largest  of  which  have  a  diameter  nearly  one-eighth  as  great  as  that  of  the 
body  itself,  and  the  smallest  of  which  are  very  much  smaller.  These  are 
not  arranged  so  as  to  give  rise  to  any  distinct  tessellation.  Toward  the  end 
of  the  intestine  the  granules  again  become  less  abundant  and  smaller,  so 
that  for  some  distance  in  front  of  the  rectum  there  is  only  here  and  there 
a  granule.  From  the  depressed  and  conspicuous  anus  the  chitinized  rec- 
tum, which  is  a  little  longer  than  the  anal  body  diameter,  extends  inward 
and  forward.  There  is  no  distinct  pre-rectum.  The  tail  end  begins  to  taper 
from  a  long  distance  in  front  of  the  anus,  but  tapers  very  gradually  to 
behind  the  anus.  Thence  onward  it  is  inclined  to  be  arcuate  and  tapers 
regularly  to  near  the  terminus.  Near  the  end  it  tapers  more  rapidly  than 
elsewhere,  and  finally  comes  to  an  almost  acute  point  at  the  terminus.  A 
short  distance  in  front  of  the  terminus,  however,  the  diameter  is  about  half 
as  great  as  it  is  at  the  anus.  There  does  not  appear  to  be  any  spinneret,  and 
therefore,  of  course,  caudal  glands  are  absent.  The  lateral  fields  appear  to 
be  about  one-third  as  wide  as  the  body.  Nothing  is  known  concerning  the 
excretory  pore.  From  the  slightly  elevated  vulva  the  vagina  leads  inward 
nearly  at  right  angles  to  the  surface  more  than  halfway  across  the  body, 
where  it  joins  the  single  uterus,  which  extends  backward.  The  ovary  is 
reflexed,  and  the  blind  end  is  about  halfway  back  to  the  vulva.  The  eggs 
occur  in  the  uterus  one  or  two  at  a  time,  and  are  very  much  elongated.  They 
are  about  six  times  as  long  as  the  body  is  wide,  and  about  one-eighth  as  wide 
as  long,  and  are  covered  by  a  distinct,  smooth  shell.  They  are  apparently 
deposited  before  segmentation  begins.  The  spermatozoa  appear  to  be  elon- 
gated-ellipsoidal, and  a  little  more  pointed  at  one  end  than  at  the  other.  They 
have  a  length  one-fifth  that  of  the  body  diameter. 
68 


2.3mm. 


•3  -6  .7  .9  .7 
The  tail  of  the  male  is  like  that  of  the  female  in  form  and  size,  but 
the  anus  is  somewhat  elevated.  In  front  of  the  anus  there  appears  to  be  a 
ventral  row  of  very  obscure,  broad,  flattish  supplementary  organs.  Perhaps 
these  ought  to  be  described  as  locations  of  nerve  endings  rather  than 
as  distinct  organs.  Their  number  remains  doubtful,  but  there  are  about 


FREE-LIVING   FRESH-WATER   NEMATODES  53 

three  or  four  occupying  a  distance  equal  to  half  the  length  of  the  tail. 
The  two  equal,  straight  spicula  are  rather  obscure.  Their  length  is  no 
greater  than  the  length  of  the  anal  body  diameter.  Oblique  copulatory 
muscles  are  seen  in  the  vicinity  of  the  spicula,  and  there  is  a  refrac- 
tive element  passing  backward  from  the  accessory  piece  toward  the 
ventral  side  of  the  tail  near  the  anus,  which  may  be  muscular,  or 
possibly  chitinous  and  serving  for  the  attachment  of  muscles.  The 
ejaculatory  duct  is  about  one-third  as  wide  as  the  body,  the  vas  def- 
erens  somewhat  wider.  Whether  there  are  two  testes  or  only  one  has 
not  been  determined.  There  is  a  broad,  rounded,  blunt  end  of  a 
testis  located  as  far  behind  the  base  of  the  neck  as  this  latter  is  behind 
the  anterior  extremity. 

Habitat:     Big  Lake,  Fla.     Bouin  solution  to  glycerine. 

PLECTUS,  Bastian,   1865. 
Fig.  10,  Plate  IV. 

35 

2.         10.7      IQ.         '49'      92.6 

10.     Plectus  tubifer,  n.sp.  .74  mm. 

2.1      34      3-5     3-2      2.3 

The  skin  is  of  medium  thickness,  colorless,  and  traversed  transversely 
by  fine,  plain  striae.  The  striae  are  of  such  a  size  that  about  twenty  of  them 
occupy  a  space  equivalent  to  the  body  diameter.  There  are  no  hairs  on*  the 
surface  of  the  body,  but  throughout  the  length  of  the  body,  more  particularly 
on  the  submedian  lines,  may  be  seen  very  faint  markings  in  the  cuticle,  which 
indicate  the  location  of  four  rows  of  pores  connecting  with  interior  organs. 
Immediately  behind  the  lateral  organs  one  sees  the  first  of  the  series  of  pores 
located  in  the  lateral  line.  This  first  pore,  though  much  smaller  than  the 
lateral  organs,  is  yet  somewhat  larger  than  the  succeeding  ones,  which  grad- 
ually spread  out  to  form  two  submedian  rows.  The  total  number  of  these 
pores  on  one  side  (of  the  male)  is  about  one  hundred;  that  is,  there  are  about 
two  hundred  in  all.  The  six  low,  rounded  lips  are  rather  massive,  and  are 
arched  together  over  the  pharynx.  These  lips  appear  to  be  armed  with 
chitinous  processes  on  the  inner  surface,  these  processes  surrounding  a  short 
napiform  vestibule  leading  to  the  pharynx  proper.  If  any  labial  papillae  are 
present  they  are  exceedingly  minute ;  what  appear  to  be  traces  of  papillae 
may  occasionally  be  seen.  The  lateral  organs  are  well  forward,  being  lo- 
cated only  slightly  behind  the  cephalic  setae.  They  present  transversely 
elongated  contour  markings  open  on  the  posterior  margin.  The  lateral  fields 
appear  to  attain  a  considerable  width  and  two  chitinous,  lateral  markings 
close  together  with  a  third  between  them,  appear  to  indicate  the  existence  of 
a  wing  on  each  side  of  the  body. 


54  NORTH    AMERICAN 


54 
1.9    10.1     19.2    '-M    91.5 

79  mm 

2.        3-1       34     3-6       3-3 
2.4     10.       19.5     '-M     93. 

3-2      3-3 

possessed  four  supplementary  organs,  the  additional  one  being  some  little 
distance  in  front  of  the  others,  which  were  arranged  as  illustrated. 
Sometimes  there  are  only  two  of  these  organs,  one  smaller  than  the  other. 
The  cuticle  of  the  ventral  surface  is  slightly  thickened  and  elevated  where 
it  is  pierced  by  these  tubular  organs,  which  appear  in  some  instances  to  be 
slightly  exserted.  Apart  from  these  preanal  supplementary  organs,  there 
are  ventrally  submedian  papillae  on  the  tail ; — one  pair  near  the  middle,  an- 
other pair  half  way  between  these  and  the  anus,  and  a  third  pair  part  way 
from  that  first  mentioned  to  the  terminus.  There  is  a  fourth  pair  indistinctly 
to  be  seen  just  behind  the  anus;  these  are  closer  together  than  the  members 
of  the  other  pairs.  Furthermore  there  are  one  or  two  very  small  pairs  near 
the  terminus,  but  perhaps  these  may  partake  more  of  the  nature  of  hairs 
than  of  papillae.  Just  in  front  of  the  anus  there  is  a  single  ventral  almost 
setose  papilla.  There  occur  in  front  of  the  anus  at  least  two  pairs  of  ven- 
trally submedian  papillae.  These  are  located  one  just  in  front  of  the  pos- 
terior supplementary  organ  and  the  other  just  behind  it.  Most  of  these 
features  are  not  easy  to  decipher,  very  careful  observation  being  necessary  to 
enumerate  the  papillae  as  above.  There  are  two  testicles,  one  anterior  to 
the  other,  the  anterior  being  outstretched  and  extending  forward,  the  pos- 
terior being  reflexed  near  its  middle,  so  that  its  blind  end  lies  somewhere 
near  the  junction  of  the  two.  The  anterior  one  of  this  pair  is  connected 
with  the  seminal  vesicle  by  a  tubular  portion,  which  lies  alongside  the  re- 
flexed  posterior  member. 

Habitat:     Arlington,  Va.     Flemming  solution  to  glycerine. 

DORYLAIMUS,  Dujardin,  1845. 
Fig.  12,  Plate  V. 

43 

11.     Dorylaimus  fecundus,  n.sp.     — : '- —    3.4  mm. 

.5     i.i       1.6     1.9      1.2 

The  thin  layers  of  the  transparent,  colorless,  naked  cuticle  are  traversed 
by  exceedingly  fine,  plain,  transverse  striations  resolvable  with  the  highest 
powers  of  the  microscope  under  favorable  conditions.  Longitudinal  striations 
are  visible  throughout  the  length  of  the  body.  The  presence  of  amphids  is 
indicated  by  a  transverse  marking  immediately  behind  the  lip  region,  and 
somewhat  in  front  of  the  guiding  ring  of  the  spear.  The  anterior  contour 
of  each  organ  is  a  transverse  line  about  three-fifths  as  long  as  the  corre- 
sponding portion  of  the  head  is  wide.  Extending  backward  from  this  are 
lateral  contours  which  approach  each  other  slightly  and  end  indefinitely.  The 


FREE-LIVING  FRESH-WATER   NEMATODES  55 

oesophagus  begins  as  a  tube  about  half  as  wide  as  the  corresponding  portion 
of  the  neck,  and  continues  to  have  this  diameter  until  near  the  middle  of 
the  neck,  where  it  first  begins  to  expand.  A  little  behind  the  middle  of  the 
neck  it  expands  rather  suddenly,  so  that  the  remainder  of  the  organ  is  about 
two-thirds  as  wide  as  the  base  of  the  neck.  There  is  a  much  elongated 
conoid  cardia  nearly  as  long  as  the  body  is  wide.  The  intestine,  which  be- 
comes at  once  three-fourths  as  wide  as  the  body,  is  separated  from  the 
oesophagus  by  a  distinct  though  slight  constriction.  The  cells  forming  the 
intestine  are  of  such  a  size  that  about  four  or  five  are  required  to  build  a 
circumference.  They  contain  granules  of  variable  size,  the  larger  of  which 
have  a  diameter  equal  to  the  thickness  of  the  outer  transparent  cuticle,  and 
the  smaller  a  diameter  only  about  one-fourth  as  great  as  that  of  the  larger. 
These  granules  are  so  arranged  as  to  give  rise  to  a  very  obscure  tesselation. 
The  pre-rectum  is  about  three  to  four  times  as  long  as  the  corresponding 
body  diameter,  and  is  separated  from  the  intestine  by  a  difference  in  struc- 
ture, the  granules  contained  in  its  cells  being  smaller,  and  not  darkening  un- 
der the  influence  of  osmic  acid,  as  do  those  of  the  intestine.  Nothing  is 
known  concerning  the  salivary  glands  or  the  renette.  The  longitudinal  fields 
are  well  developed,  being  about  half  as  wide  as  the  body.  The  nerve-ring 
surrounds  the  oesophagus  somewhat  obliquely.  Each  of  the  two  elongated 
uteri  may  contain  three  to  five  eggs  at  a  time.  These,  as  they  appear  in  the 
uteri,  are  elongated,  finely  granular,  rather  thin-shelled,  and  about  one  and 
one-half  times  as  long  as  the  body  is  wide,  and  about  half  as  wide  as  long. 
The  shells  are  flexible,  so  that  owing  to  the  pressure  of  one  egg  on  another 
in  the  uterus  the  surfaces  are  often  indented. 


3-5  mm. 


.6    1.2      1.4     1.4        1.4 

In  addition  to  the  ventral  row  of  supplementary  male  organs  shown  in 
the  illustration,  there  are  two  rows  of  ventrally  submedian,  innervated  papil- 
lae, arranged  in  a  somewhat  equidistant  manner.  Where  these  reach  the 
surface  of  the  body  they  give  rise  to  almost  imperceptible  elevations  which, 
however,  are  of  a  different  character  from  those  at  the  ends  of  the  ventral 
organ  shown  in  p,  Fig.  12.  In  other  words,  these  papillae  are  more  nearly  the 
homologues  of  the  ordinary  tactile  hairs  or  papillae  so  common  on  the  sur- 
face of  nematode  worms.  These  submedian  papillae  are  located  at  a 
distance  from  each  other  equal  to  about  two-thirds  the  body  diameter. 
They  are  very  nearly  coextensive  with  the  oblique  copulatory  muscles. 

Habitat:  Algae,  Potomac  River,  Washington,  D.  C,  1911.  Flem- 
ming  solution  to  glycerine. 


56  NORTH    AMERICAN 

IRONUS,  Bastian,  1865. 

Fig.  13,  Plate  V. 

30 

12.     Ironus  americanus,  n.sp.  — : : —   2.3  mm. 

1.6    2.3      2.7    2.9       1.3 

The  moderately  thin  layers  of  the  transparent,  colorless,  naked  cuticle 
appear  to  be  destitute  of  striations.  There  are  three  somewhat  conoid  lips, 
which  when  open,  give  to  the  head  a  somewhat  truncated  appearance,  when 
folded  a  somewhat  rounded  appearance.  Each  lip  bears  internally  a  slightly 
arcuate,  conical  tooth,  whose  altitude  is  somewhat  greater  than  the  width 
of  its  base.  When  the  mouth  is  so  opened  that  the  apices  of  these  refractive 
teeth  are  about  on  a  level  with  the  anterior  extremity  their  bases  lie  a  little 
in  front  of  the  bases  of  the  cephalic  setae.  The  apices  of  these  teeth  are 
slightly  blunt  and  they  have  a  slight  outward  curvature.  The  walls  of  the 
pharynx  are  strongly  refractive,  and  have  about  the  same  thickness  as  the 
walls  of  the  cuticle.  The  chitin  of  the  walls  of  the  pharynx,  however,  is 
more  refractive  than  that  of  the  cuticle.  In  this  respect  it  resembles  the 
chitin  of  which  the  teeth  are  composed.  Except  for  the  teeth  at  the  mouth 
opening  the  pharynx  is  unarmed,  but  presents  on  the  dorsal  side  about  half 
way  between  the  head  and  its  posterior  extremity  three  or  four  exceedingly 
minute  projections  with  corresponding  depressions.  The  oesophagus  begins 
near  the  base  of  the  pharynx,  at  least  it  is  at  this  point  that  the  radial  struc- 
ture becomes  pronounced.  At  first  it  is  about  two-thirds  as  wide  as  the  cor- 
responding portion  of  the  neck.  It  enlarges  a  little  and  very  gradually,  so  that 
finally  it  is  about  half  as  wide  as  the  base  of  the  neck.  The  lining  of  the 
oesophagus  is  an  exceedingly  distinct  feature  throughout  its  length.  It  gen- 
erally has  the  appearance  of  three  refractive  lines  occupying  a  space  nearly 
one-fourth  as  wide  as  the  oesophagus  itself.  There  is  a  large  cylindroid 
or  hemispherical  cardia,  one-third  as  wide  as  the  base  of  the  neck.  The  in- 
testine, which  is  separated  from  the  oesophagus  by  a  deep,  narrow  and  dis- 
tinct constriction,  becomes  at  once  about  three-fifths  as  wide  as  the  body. 
Its  cells  contain  scattered  granules  of  variable  size,  the  largest  of  which  have 
a  diameter  nearly  equal  to  the  width  of  the  refractive  portion  of  the  lining  of 
the  oesophagus,  and  the  smallest  of  which  have  a  diameter  not  more  than 
one-tenth  as  great.  The  body  wall  is  thick,  generally  occupying  about  three- 
fifths  of  the  diameter  of  the  body.  The  lateral  fields  are  a  little  more  than 
one-third  as  wide  as  the  body.  Nothing  is  known  concerning  the  renette 
or  the  excretory  pore.  There  is  no  spinneret.  The  tail,  nevertheless,  con- 
tains small  cells  near  the  anus  which  bear  a  certain  resemblance  to  the  ordi- 
nary caudal  glands.  From  the  slightly  elevated  vulva,  the  vagina  leads  in- 
ward at  right  angles  to  the  ventral  surface  half  way  across  the  body  where 
it  joins  the  two  symmetrically-placed  uteri.  The  reflexed  ovaries  reach 
three-fourths  the  distance  back  to  the  vulva,  at  least  in  specimens  which  do 
not  contain  eggs.  The  ovaries  contain  about  a  dozen  ova  arranged  for  the 


FREE-LIVING   FRESH-WATER   NEMATODES  57 

most  part  single  file.  Nothing  very  definite  is  known  concerning  the  form 
and  size  of  the  eggs,  but  from  the  size  of  the  apparently  matured  ova  it  is 
assumed  that  the  eggs  are  considerably  elongated,  perhaps  two  to  two  and 
one-half  times  as  long  as  the  body  is  wide,  and  if  so,  it  is  unlikely  that 
more  than  one  is  contained  in  the  uterus  at  a  time. 

Habitat:  Deer  Bottom,  Pikes  Peak  region,  Colorado.  Formalin  to 
glycerine. 

ONCHOLAIMUS,  Dujardin,  1845. 

Fig.  14,  Plate  V. 
13.     Oncholaimus  punctatus,  n.sp. 

The  rather  thin.,  transparent,  colorless  layers  of  the  naked  cuticle  appear 
to  be  destitute  of  striations.  It  is  rather  difficult  to  observe  the  cuticle  on 
account  of  the  presence  in  it  of  numerous  dot-like  elements,  which  near  the 
head  are  arranged  in  longitudinal  groups,  of  which  the  widest  is  the  lateral 
group.  The  longitudinal  arrangement  of  the  granules,  is  continuous  through- 
out the  body,  but  it  is  most  marked  on  the  lateral  fields  where  there  is  a 
definite  band  of  them,  having  a  width  about  two-fifths  as  great  as  the  width 
of  the  body.  Each  margin  of  this  band  is  made  up  of  a  distinct  longitudinal 
row  of  granules  arranged  single  file.  The  neck  is  slightly  conoid,  becoming 
slightly  convex-conoid  toward  the  rounded  head,  which  is  not  set  off  in  any 
way,  or  at  most  by  an  exceedingly  obscure,  broad  constriction  opposite  the 
pharynx.  The  six  lips  are  distinct  and  well  developed  and  have  a  distinct, 
somewhat  chitinous  framework.  They  are  arched  together  over  the  pharynx 
in  such  a  way  as  to  produce  a  dome-like  effect,  the  very  thin  and  movable 
flaps  at  the  ends  of  the  lips  meeting  together  at  the  middle  of  the  front  of 
the  head.  Opposite  the  middle  of  the  amphids  there  is  a  transverse  marking 
or  line  which  extends  around  the  middle  of  the  head.  It  is  characterized  by 
staining  somewhat  more  strongly  with  carmine  than  the  other  portions  of 
the  cuticle.  There  are  no  eye-spots.  The  oesophagus  begins  at  the  base  of 
the  pharynx  with  a  diameter  three-fourths  as  great  as  that  of  the  base  of  the 
head,  and  it  continues  to  have  this  diameter  until  some  distance  behind  the 
nerve-ring.  It  then  begins  to  expand  gradually,  so  that  finally  it  is  about 
three-fourths  to  four-fifths  as  wide  as  the  base  of  the  neck.  The  lining  is  a 
distinct  feature  throughout  the  length  of  the  oesophagus.  There  is  a  dis- 
tinct conoid  cardia,  whose  base  is  about  half  as  wide  as  the  corresponding 
portion  of  the  body.  The  intestine,  which  is  separated  from  the  oesophagus 
by  a  deep  and  distinct  constriction,  appears  to  have  rather  thin  walls  and  to 
be  composed  of  cells  of  such  a  size  that  probably  six  or  more  would  be  re- 
quired to  build  a  circumference.  These  cells  contain  numerous  granules  of 
rather  uniform  size. 

The  lateral  fields  are  about  two-fifths  as  wide  as  the  body.  The  loca- 
tion of  the  ventral  gland  has  not  been  made  out.  The  excretory  pore  is  lo- 


58  NORTH    AMERICAN 

cated  just  behind  the  base  of  the  pharynx.    The  duct  which  leads  to  it  seems 
to  be  destitute  of  an  ampulla. 
40 

1.9     10.2    21.4    -M-    92. 

_ - 2.1  mm. 

1.2        2.2        2.8        2.5          1.8 

In  front  of  the  anus  there  is  a  series  of  about  fifty  pairs  of  oblique 
copulatory  muscles,  whose  presence  is  indicated  by  the  oblique  groups  of 
granules  in  the  cuticle.  The  ejaculatory  duct  is  about  one-third  as  wide  as 
the  body.  The  blind  end  of  the  anterior  testicle  is  about  twice  as  far  behind 
the  base  of  the  neck  as  this  latter  is  behind  the  anterior  extremity. 

Habitat :  Fresh  water  ponds,  Cape  Breton  Island,  Dominion  of  Canada. 
Sublimate  to  balsam. 

DOLICHODORUS,  n.g. 
Fig.  16,  Plate  VI. 

58 

14.     Dolichodorus  heterocephalus,  n.sp.'3  (34)  7'*  9'*  '52'  97'2  3.  mm. 

.6  (i.i)   1.6  1.7    2.1      1.2 

The  thin  layers  of  the  transparent,  naked,  colorless  cuticle  are  traversed 
by  transverse  striae  resolvable  with  high  powers  under  favorable  conditions 
into  rows  of  exceedingly  minute,  somewhat  irregular  elements.  This  reso- 
lution is  not  at  all  difficult  in  specimens  which  are  moulting.  Under  these 
conditions  scales  of  the  outer  cuticle  sometimes  survive,  readily  resolvable 
into  refractive  transverse  markings  between  which  are  the  small  elements 
mentioned.  Ordinarily  at  first  glance,  the  cuticle  appears  to  be  merely  re- 
solvable into  transverse  striae  which  are  somewhat  roughened  on  the  edges 
of  the  dividing  lines.  The  conoid  neck  ends  in  a  head  which  has  a  very 
prominent  lip-region  set  off  by  a  very  prominent  and  deep  constriction.  The 
front  of  the  head  is  rounded,  and  the  constriction  separating  the  lip-region 
from  the  remainder  of  the  head  is  of  such  a  nature  that  the  contour  of  the 
lip-region,  when  seen  in  optical  longitudinal  section  is  somewhat  elliptical,  so 
that  the  lip-region  has  the  form  of  an  ellipsoid  of  rotation.  The  depth  of 
this  figure  is  about  equal  to  half  its  width.  No  papillae  have  been  seen  on 
the  lips,  but  minute  papillae  might  readily  be  present  without  having  been 
observed.  No  traces  of  amphids  have  been  seen.  There  are  no  eye-spots. 
The  vestibule  is  exceedingly  narrow  and  closely  surrounds  the  apex  of  the 
very  slender  narrow  spear.  This  latter  extends  nearly  half-way  to  the  an- 
terior border  of  the  median  bulb  and  is  long  and  slender  like  that  of 
Trichodorus.  The  oesophagus  at  the  base  of  the  spear  is  a  tube  about  one- 
third  as  wide  as  the  corresponding  portion  of  the  neck,  and  continues  to  have 
this  diameter  until  it  expands  suddenly  to  form  the  elongated  median  bulb, 
which  is  three-fourths  as  wide  as  the  corresponding  portion  of  the  neck  and 
fully  twice  as  long  as  wide  and  is  armed  internally  with  a  conspicuous,  ellip- 
soidal, rather  simple  valvular  apparatus  nearly  half  as  wide  as  itself.  When 


FREE-LIVING   FRESH-WATER   NEMATODES  59 

seen  in  optical  longitudinal  section  the  bulb  is  a  little  wider  posteriorly  than 
anteriorly,  so  that  its  sides  are  not  parallel,  but  approach  each  other  a  trifle 
as  they  pass  forward.  The  bulb  ends  more  abruptly  posteriorly  than  an- 
teriorly, and  is  continued  by  a  narrow  section  of  the  oesophagus  only  one- 
eighth  as  wide  as  the  corresponding  portion  of  the  neck  and  about  as  long 
as  the  corresponding  portion  of  the  neck  is  wide.  This  is  succeeded  by  a 
broadly  clavate  swelling  which  does  not  have  any  distinct  chitinous  lining, 
and  is  of  granular  structure,  rather  than  muscular.  This  swelling  is  about 
two-thirds  as  wide  as  the  base  of  the  neck.  The  lining  of  the  oesophagus 
is  a  fairly  distinct  feature  in  all  parts  in  front  of  the  posterior  swelling. 
The  intestine  joins  the  middle  of  the  rounded  surface  of  the  posterior  oeso- 
phageal  swelling  and  is  at  this  point  only  one-tenth  to  one-eighth  as  wide 
as  the  corresponding  portion  of  the  body,  but  soon  expands  to  be  two-fifths 
as  wide  as  the  body.  It  is,  therefore,  relatively  narrow.  On  the  other  hand, 
the  body  walls  are  correspondingly  thick.  Nothing  is  known  concerning 
the  renette  cell.  It  is  probable  that  there  is  an  excretory  pore  located  near 
the  nerve-ring. 

60 

.3     (2.3)     7.9     10.9    -M      99.3 

2.4  mm. 

.4     (  .8)     1.2       1.4      1.7        1.8 

The  tail  of  the  male  is  conoid  and  extends  beyond  the  anus  a  distance 
hardly  as  great  as  the  length  of  the  anal  body  diameter.  It  seems  likely  that 
the  tail  is  also  flattish.  When  seen  dorso-ventrally  it  appears  to  be  about  one- 
half  as  long  as  the  spicula,  and  ends  in  a  dentate  terminus  one-third  as 
wide  as  the  base  of  the  tail.  The  cuticle  of  the  tail  is  very  thick,  and  at 
first  sight  seems  rather  closely  to  resemble  the  structure  of  the  two  bursal 
flaps.  The  distinctly  two-parted  bursa  springs  from  opposite  the  middle  of 
the  spicula  and  extends  backward  and  is  completely  furcated  at  a  point 
about  opposite  the  base  of  the  tail.  The  flaps  extend  backward  beyond  the 
terminus  of  the  tail  and  give  to  the  posterior  extremity  somewhat  the  appear- 
ance of  ending  in  three  thin  transparent,  colorless  flaps,  one  of  which  is 
soon  seen  to  be  the  true  caudal  extension.  The  flaps  of  the  bursa  are  striated 
in  much  the  same  manner  as  the  cuticle,  and  the  margins  of  the  flaps  are 
distinctly  thickened.  No  distinct  ribs  have  been  seen  in  the  two  broad 
backward  pointing  flaps  of  the  bursa.  The  two  equal,  rather  strongly  built, 
tapering  spicula  have  a  length  about  one  and  one-half  times  as  great  as  that 
of  the  diameter  measured  opposite  their  proximal  ends.  They  are  accom- 
panied by  a  rather  simple  accessory  piece  one-half  as  long  as  themselves, 
judging  from  its  appearance  when  seen  dorso-ventrally.  The  proximal  ends 
of  the  spicula  can  hardly  be  said  to  be  cephalated,  but  they  are  obliquely 
trancated  and  wider  than  elsewhere.  When  seen  dorso-ventrally  this  width 
appears  to  be  one-fourth  as  great  as  that  of  the  corresponding  portion  of 
the  body.  No  special  setae  are  present  and  no  special  papillae  have  been 
seen.  The  single  outstretched  testicle  extends  forward  and  has  its  blind 
end  located  about  three  to  four  times  as  far  behind  the  base  of  the  neck 


60  NORTH    AMERICAN 

as  this  latter  is  behind  the  anterior  extremity.  Near  its  blind  end  its  diam- 
eter is  about  one-half  as  great  as  that  of  the  body.  The  spermatozoa  art 
small  and  numerous  and  it  appears  that  the  reduction  divisions  take  place  in 
a  short  segment  of  the  testis  not  far  from  the  blind  end. 

Habitat:  Freshwater,  Douglas  Lake,  Michigan.  Silver  Spring,  Florida. 
Female,  Flemming  solution  to  glycerine;  from  Florida.  Male,  from  Michi- 
gan, sublimate  to  balsam. 

CYATHOLAIMUS,  Bastian,  1865. 

Fig.  17,  Plate  VI. 

26. 

15.     Cyatholaimus  truncatus,  n.sp. : : — —  1.6  mm. 

1.8    2.        2.1      3.3         2.1 

The  moderately  thick  layers  of  the  transparent,  colorless,  naked  cuticle 
are  traversed  by  about  fifteen  hundred  transverse  striae,  resolvable  into 
transverse  rows  of  distinct  dots,  which  are  not  very  materially  modified  in 
the  lateral  fields.  The  slightly  conoid  neck  ends  in  a  truncated  head,  whose 
lip  region  is  set  off  by  an  almost  imperceptible  expansion.  The  cuticle  be- 
comes somewhat  thicker  toward  the  head,  and  the  dotlike  markings  more 
distinct  and  refractive.  Beginning  near  the  head  and  ending  near  the  spin- 
neret there  are  circular  markings  arranged  in  somewhat  irregular  rows 
along  the  lateral  fields.  The  longitudinal  distance  between  these  markings 
near  the  middle  of  the  body  is  a  little  greater  than  the  radius  of  the  body, 
and  the  diameter  of  the  circles  is  somewhat  greater  than  the  width  of  one 
of  the  annules,  sometimes  twice  as  great.  These  markings  are  not  all  of  the 
same  size,  some  being  nearly  twice  as  large  as  others.*  The  lip  region  is 
twelve-parted,  and  there  are  twelve  longitudinal  chitinous  structures  sur- 
rounding the  vestibule.  These  no  doubt  indicate  the  infolding  of  the  lips 
when  closed.  Probably  the  best  conception  of  the  lip  region  is  expressed  by 
saying  that  there  are  six  lips,  each  two-parted,  but  that  the  divisions  are  all 
very  similar  to  each  other.  On  the  front  of  the  lips  there  are  six  forward 
pointing  innervated  papillae  arranged  in  the  usual  position.  Along  the  outer 
margin  of  the  head  there  are  ten  acute,  tapering,  cephalic  setae,  two  lateral, 
and  four  submedian  pairs.  The  longest  of  these  setae  are  about  equal  to 
the  radius  of  the  head.  According  to  the  position  of  the  lips  these  setae 
vary  in  attitude.  They  may  be  folded  together  on  the  front  of  the  head  so 
as  to  be  in  the  position  of  the  spokes  of  a  wheel,  but  they  may  point 
forward  when  the  mouth  is  partly  open,  and  are  in  a  somewhat  spreading 
position  when  the  mouth  is  wide  open.  The  pharynx  is  on  the  whole  con- 
oid, and  about  three-fourths  as  deep  as  the  head  is  wide.  Springing  from  a 
little  behind  its  middle  is  a  strong,  conical,  acute,  forward  pointing  dorsal 
tooth,  the  ventral  contour  of  which  lies  approximately  in  the  axis  of  the 


*The  two  most  pronounced  rows  are  nearly  opposite  the  edges  of  the  lateral  fields, 
but  there  is  an  irregular  median  row. 


FREE-LIVING   FRESH-WATER    NEMATODES  6l 

head.  Surrounding  the  pharynx  the  muscles  are  somewhat  more  powerful 
than  in  the  oesophagus  immediately  behind,  so  that  there  is  a  very  faint 
pharyngeal  bulb.  The  oesophagus  is  at  first  about  two-thirds  as  wide  as 
the  corresponding  portion  of  the  neck,  but  gradually  enlarges  after  passing 
through  the  nerve-ring,  so  that  finally  it  is  two-thirds  as  wide  as  the  base 
of  the  neck.  The  lining  of  the  oesophagus  is  a  distinct  feature  throughout 
its  length.  There  is  no  very  distinct  cardia.  There  are  no  eye-spots.  The 
amphids,  which  are  about  one-third  as  wide  as  the  head,  are  spirals  of  about 
two  and  one-half  winds,  and  are  placed  opposite  the  apex  of  the  dorsal 
tooth.  The  intestine,  which  is  separated  from  the  oesophagus  by  a  distinct 
constriction,  is  at  first  one-half  to  two-thirds  as  wide  as  the  body,  but  in  the 
greater  part  of  its  length  is  about  two-thirds  as  wide  as  the  body.  It  is 
thick  walled,  and  is  composed  of  cells  of  such  a  size  that  comparatively  few 
are  required  to  build  a  circumference,  probably  about  six.  The  cells  con- 
tain rather  numerous,  conspicuous,  brownish  granules  of  variable  size,  the 
largest  of  which  have  a  diameter  about  equal  to  double  the  width  of  one 
of  the  annules  of  the  cuticle,  the  smallest  of  which  are  very  much  smaller. 
These  granules  are  arranged  irregularly,  and  can  hardly  be  said  to  suggest 
any  tessellation.  From  the  broad,  raised  anus  the  rectum,  which  is  refractive 
and  nearly  as  long  as  the  anal  body  diameter,  extends  inward  and  forward. 
The  tail  is  conoid  to  the  subacute  conoid  spinneret,  which  has  a  diameter 
about  one-eighth  to  one-tenth  as  great  as  that  of  the  base  of  the  tail.  There 
do  not  appear  to  be  any  caudal  setae.  The  lateral  fields  appear  to  be  fully 
one-third  as  wide  as  the  body.  The  nerve-ring  surrounds  the  oesophagus 
somewhat  obliquely.  The  excretory  pore  appears  to  be  situated  at  a  distance 
from  the  anterior  extremity  about  two  and  one-half  times  as  great  as  the 
width  of  the  head.  The  renette  cell  appears  to  be  small  and  located  some 
distance  behind  the  base  of  the  neck.  From  the  elevated  vulva  the  vagina 
leads  inward  at  right  angles  to  the  ventral  surface  about  half  way  across 
the  body,  where  it  joins  the  two-parted  uterus.  The  reflexed,  tapering 
ovaries  reach  about  two-thirds  the  way  back  to  the  vulva,  and  contain  a 
dozen  or  more  developing  ova  arranged  somewhat  irregularly,  especially 
toward  the  blind  end.  The  rather  thin  shelled  ovate  to  ellipsoidal  eggs  are 
a  little  longer  than  the  body  is  wide,  and  about  two-thirds  as  wide  as  long. 
They  have  been  seen  to  occur  in  each  uterus  one  at  a  time,  and  are  appar- 
ently deposited  before  segmentation  begins. 
59- 

1.7    6.6    15.   -M       91. 

_ I 1.6  mm. 

1.6     2.2        2.3      2.3         2.6 

The  tail  of  the  male  is  like  that  of  the  female  in  form  and  size,  but  the 
anus  is  more  prominently  elevated.  There  is  a  row  of  four  small  pre-anal, 
ventral,  tubular,  protrudable  supplementary  organs.  The  final  one  of  these 
is  opposite  the  middle  of  the  spicula ;  the  penultimate  nearly  opposite  the 
proximal  ends  of  the  spicula.  The  foremost  is  about  three  times  as  far 
from  the  anus  as  the  penultimate.  From  this  it  will  be  seen  that  the  organs 


62  NORTH    AMERICAN 

are  slightly  more  nearly  approximated  to  each  other  posteriorly.  These 
organs  are  not  conspicuous  features,  and  scarcely  disturb  the  ventral  con- 
tour. It  is  possible  that  each  is  connected  with  a  unicellular  glandular  struc- 
ture nearby.  The  two  equal,  tapering,  somewhat  arcuate  spicula  are  one  and 
one-third  times  as  long  as  the  anal  body  diameter.  Their  proximal  ends 
are  cephalated  by  expansion.  The  accessory  pieces  alongside  are  four-fifths 
as  long  as  the  spicula,  and  somewhat  broader  than  the  spicula.  In  their 
widest  part  they  are  one-sixth  as  wide  as  the  corresponding  portion  of  the 
body.  They  are  of  rather  uniform  width  throughout.  There  is  a  slight 
constriction  near  each  end,  and  the  distal  extremity  appears  to  be  very 
minutely  dentate.  The  spicula  are  about  half  as  wide  as  the  accessory  pieces. 
The  ejaculatory  duct  is  two-thirds  as  wide  as  the  corresponding  portion  of 
the  body,  as  is  also  the  testis.  The  blind  end  is  as  far  behind  the  base  of 
the  neck  as  this  latter  is  behind  the  anterior  extremity. 

Habitat:     Silver  Springs,  Fla.     Flemming  solution  to  glycerine. 

ETHMOLAIMUS,  de  Man,  1880. 

Fig.  19,  Plate  VII. 

27 

16.     Ethmolaimus  americanus,  n.sp.   — '- — - — : .6  mm. 

2.4      3.4      3.9     5.6      2.1 

The  thin,  transparent  layers  of  the  practically  naked  cuticle  are  tra- 
versed by  very  fine  transverse  striae,  resolvable  with  high  powers  into  rows 
of  closely  set  dots,  which  are  not  modified  on  the  lateral  fields.  Near  the 
head  the  dots  are  a  little  coarser  than  elsewhere  on  the  anterior  portion  of 
the  body.  On  the  tail  the  dots  are  much  farther  apart  and,  though  really 
arranged  in  transverse  rows,  at  first  glance  appear  to  be  scattered  irreg- 
ularly. The  conoid  neck  ends  in  a  somewhat  truncated  head,  which  bears 
on  its  outer  margin  a  circlet  of  four  slender,  spreading  submedian  cephalic 
setae,  each  about  half  as  long  as  the  head  is  wide.  There  appear  to  be 
twelve  minute  papillae  in  the  lip  region,  which  when  folded  together  forms 
a  rather  small,  cyathiform  cavity,  in  the  midst  of  which  stands  the  thumb- 
shaped,  forward-pointing  dorsal  tooth.  This  tooth  is  attached  to  a  dis- 
tinctly thickened  rib  of  chitin,  which  extends  from  the  lip  region  back  to  the 
base  of  the  pharynx,  and  is  thicker  anteriorly  than  it  is  posteriorly.  This 
thickened  dorsal  rib  causes  the  pharynx  to  appear  somewhat  more  strongly 
built  on  the  dorsal  side  than  on  the  ventral  side.  The  tooth  tapers  slightly 
to  a  blunt  point,  and  has  a  length  about  one-fourth  as  great  as  the  width  of 
the  front  of  the  head.  Behind  it  the  pharynx  is  somewhat  prismoid  and 
approximately  one-fifth  as  wide  as  the  head.  It  ends  abruptly  at  the  base. 
The  pharynx  is  surrounded  by  a  pharyngeal  bulb,  the  musculature  of  which 
is  set  off  distinctly  from  that  of  the  oesophagus,  in  addition  to  which  there  is 
a  constriction  between  the  bulb  and  the  oesophagus.  The  somewhat  obscure, 
slender,  apparently  spiral  amphids  consist  of  about  one  and  one-half  winds. 
They  are  located  opposite  the  posterior  portion  of  the  pharynx,  and  are  one- 


FREE-LIVING   FRESH-WATER   NEMATODES  63 

third  as  wide  as  the  corresponding  portion  of  the  head.  There  are  no  eye- 
spots.  The  oesophagus  begins  as  a  tube  three-fifths  as  wide  as  the  base  of  the 
head,  and  it  continues  to  have  this  diameter  until  it  expands  rather  sud- 
denly to  form  a  somewhat  ellipsoidal  or  obscurely  pyriform  cardiac  bulb, 
which  is  four-fifths  as  wide  as  the  base  of  the  neck,  and  contains  an  obscure, 
elongated,  relatively  narrow  valvular  apparatus.  The  lining  of  the  oeso- 
phagus is  a  distinct  feature  throughout  its  length.  There  is  no  very  dis- 
tinct cardia,  but  the  preliminary  cells  of  the  intestine  are  different  from  those 
which  immediately  follow.  The  rather  thick-walled  intestine  is  separated 
from  the  oesophagus  by  a  deep  and  distinct  constriction,  and  becomes  at 
once  about  half  as  wide  as  the  body.  Thereafter  it  widens  out  gradually  so 
as  to  become  three-fourths  as  wide  as  the  body.  It  is  composed  of  cells  of 
such  a  size  that  probably  about  six  to  eight  are  required  to  build  a  circum- 
ference. The  cells  contain  granules  of  variable  size,  the  largest  of  which  have 
a  diameter  half  as  great  as  that  o'f  the  terminus  of  the  tail.  From  the  rather 
inconspicuous  but  slightly  depressed  anus  the  rectum,  which  is  about  as 
long  as  the  anal  body  diameter,  extends  inward  and  forward.  The  body  be- 
gins to  taper  slightly  from  some  distance  in  front  of  the  anus,  but  tapers 
more  rapidly  behind  the  anus  in  such  fashion  that  at  the  beginning  of  the 
posterior  fifth  the  diameter  is  about  one-sixth  as  great  as  at  the  anus ;  thence 
onward  the  tail  is  cylindroid,  and  ends  in  a  tubular  spinneret,  less  than  half 
as  wide  as  the  terminus.  The  spinneret  tapers  slightly  to  a  blunt  point,  and 
is  armed  at  its  base  with  one  or  more  setae  as  long  as  itself.  The  caudal 
glands  appear  to  be  located  in  the  base  of  the  tail.  The  lateral  fields  are 
well-developed  and  fully  one-third  as  wide  as  the  body.  The  renette  cell 
appears  to  be  located  a  short  distance  behind  the  cardiac  bulb.  The  position 
of  the  excretory  pore  is  unknown, — possibly  it  is  at  the  base  of  the  lips. 
The  nerve-ring  surrounds  the  oesophagus  somewhat  obliquely.  From  the 
elevated,  rather  broad  vulva  the  vagina  leads  inward  at  right  angles  to  the 
ventral  surface  fully  half  way  across  the  body,  where  it  joins  the  sym- 
metrically-placed uteri.  The  reflexed  ovaries  reach  as  far  back  as  the  vulva, 
— at  least  in  specimens  in  which  the  uteri  contain  no  eggs.  The  fully  de- 
veloped ova  are  nearly  twice  as  long  as  the  body  is  wide  and  about  one- 
third  as  wide  as  long.  The  form,  size  and  number  of  the  eggs  remains  un- 
determined, but  it  seems  probable  that  they  occur  in  the  uteri  one  at  a  time. 
Habitat:  Spring,  Washington  Country  Club,  Ctu.y  Chase,  Md. 
Sublimate  to  balsam. 

MONHYSTERA,  Bastian,  1865. 

Fig.  20,  Plate  VII. 

62. 

.6    8.7    22.    -72.        88. 
17.     Monhystera  sentiens,  n.sp.  i.o  mm. 

1.0     3-1       4-3      4-8        3-1 

The   thin,   transparent  layers   of   the  colorless  cuticle  are  traversed  by 
about  eight  hundred  transverse  striae,  resolvable  with  difficulty  into  rows  of 


64  NORTH    AMERICAN 

somewhat  dotlike  elements.  These  striae  are  more  readily  visible  toward 
the  extremities,  especially  the  posterior  extremity.  The  conoid  neck  becomes 
convex-conoid  toward  the  head,  which  is  somewhat  rounded.  Throughout 
the  body  there  are  rather  numerous,  long,  slender  somatic  setae  having  a 
length  equal  to  the  radius  of  the  body.  These  setae  are  a  little  longer  toward 
the  extremities  than  they  are  near  the  middle  of  the  body.  On  the  outer 
margin  of  the  head,  a  trifle  in  front  of  the  base  of  the  pharynx,  there  are 
ten  spreading,  tapering  cephalic  setae,  one  on  each  lateral  line,  and  two  of 
somewhat  unequal  size  on  each  submedian  line.  The  longest  of  these  setae 
are  more  than  half  as  long  as  the  head  is  wide.  A  little  more  than  twice  as 
far  back  as  the  amphids  there  is  a  rather  definite  circlet  of  cervical  or  sub- 
cephalic  setae  arranged  in  submedian  positions.  The  lips  appear  to  be  three 
in  number,  and  are  longitudinally  striated  or  fluted.  The  thin  flap-like,  stri- 
ated portions  are  capable  of  assuming  a  revolute  position.  The  basal  por- 
tion of  the  lip  region  is  considerably  thicker  than  the  flaps,  and  is  arched 
over  the  margin  of  the  pharynx.  This  latter  is  wide  and  shallow.  Just 
beneath  the  lips  it  is  two-thirds  as  wide  as  the  front  of  the  head.  It  closes 
together  rapidly,  so  that  its  base  is  located  at  a  distance  from  the  anterior 
extremity  about  equal  to  the  radius  of  the  head.  In  other  words,  the  pos- 
terior portion  of  the  pharynx  is  about  half  way  back  to  the  amphids.  These 
latter  are  circular,  and  one-third  to  one-fourth  as  wide  as  the  correspond- 
ing portion  of  the  head.  Their  distance  from  the  anterior  extremity  is  about 
equal  to  half  the  width  of  the  front  of  the  head.  A  short  distance  in  front 
of  each  amphid  there  is  a  granular  nucleus,  which  closely  resembles  the 
nerve  cells  that  are  found  in  the  neck,  and  seems  doubtless  to  be  the  nucleus 
of  the  nerve  cell  which  is  connected  in  some  way  with  the  function  of  the 
amphids.  The  oesophagus  reaches  to  the  base  of  the  lips,  and  into  it  is  set 
the  posterior  portion  of  the  pharynx.  At  first  the  oesophagus  is  only  two- 
thirds  as  wide  as  the  base  of  the  head.  It  continues  to  have  this  diameter,  or 
a  little  more,  until  after  it  passes  through  the  nerve-ring.  Thence  onward  it 
gradually  increases  so  that  finally  it  is  about  two-thirds  as  wide  as  the  base 
of  the  neck.  The  lining  of  the  oesophagus  is  a  fairly  distinct  feature.  The 
intestine,  which  is  separated  from  the  oesophagus  by  a  distinct  constriction, 
is  composed  of  cells  of  such  a  size  that  probably  six  to  eight  are  required  to 
build  a  circumference.  The  anterior  portion  of  the  intestine  is  somewhat 
bulbous  in  form,  and  is  separated  from  the  oesophagus  on  the  one  side  and 
the  true  intestine  on  the  other,  by  a  pair  of  constrictions.  This  portion  may 
be  looked  upon  as  a  strongly  developed  cardia.  The  intestine  is  moderately 
thick  walled,  and  ends  posteriorly  in  a  short,  wide  rectum,  hardly  as  long  as 
the  anal  body  diameter.  The  posterior  extremity  of  the  female  begins  to 
taper  from  near  the  vulva,  and  continues  to  taper  at  about  the  same  rate 
behind  the  tail  as  in  front  of  it.  The  tail  itself  is  conoid  in  the  anterior  four- 
fifths,  and  cylindroid  in  the  posterior  fifth.  The  terminus  is  hardly  swollen, 
and  is  about  one-sixth  as  wide  as  the  base  of  the  tail.  The  spinneret  is 
rounded  and  bears  a  couple  of  submedian  setae  twice  as  long  as  its  own 


FREE-LIVING   FRESH-WATER    NEMATODES  65 

diameter.  The  three  caudal  glands  are  located  in  the  anterior  third  of 
the  tail.  The  lateral  fields  vary  in  width  in  different  parts  of  the  body. 
A  little  in  front  of  the  anus  they  are  about  two-fifths  as  wide  as  the  corre- 
sponding portion  of  the  body,  and  contain  rather  numerous  scattered  nuclei 
of  such  a  size  that  about  eight  would  be  required  to  reach  across  the  field. 
Farther  forward  the  field  is  narrower,  about  one-fourth  as  wide  as  the 
middle  of  the  body.  Anteriorly  it  is  wider,  about  one-third  as  wide  as  the 
base  of  the  neck.  Nothing  is  known  concerning  the  renette.  The  nerve- 
ring  surrounds  the  oesophagus  somewhat  obliquely  a  little  in  front  of  the 
middle  of  the  neck.  From  the  elevated  and  rather  large  and  conspicuous 
vulva  the  vagina  leads  inward  at  right  angles  nearly  half  way  across  the 
body,  where  it  joins  the  single  uterus,  which  extends  forward,  and  is  of 
such  a  size  as  to  contain  apparently  but  one  egg  at  a  time.  The  ovary,  which 
at  first  is  three-fourths  as  wide  as  the  body,  extends  forward  and  tapers 
gradually,  so  that  at  the  blind  end,  considerably  in  front  of  the  cardia  and 
a  short  distance  behind  the  nerve-ring,  it  is  one-fourth  as  wide  as  the  corre- 
sponding portion  of  the  body.  It  sometimes  happens  that  the  blind  end  of 
the  ovary  is  disposed  in  a  single  coil.  The  rather  thick  shelled  eggs  are  as 
long  as  the  body  is  wide,  and  about  three-fourths  as  wide  as  long,  and  appear 
to  be  deposited  before  segmentation  begins.  The  small  spermatozoa  found  in 
the  uterus  are  of  such  a  size  that  at  least  ten  placed  side  by  side  would  be 
required  to  span  the  diameter  of  one  of  the  eggs.  There  is  a  very  small, 
posterior  rudimentary  branch  to  the  uterus,  which  extends  backward  from 
the  vulva  a  distance  about  equal  to  two-thirds  the  radius  of  the  body. 
Around  the  vulva  are  four  distinct,  unicellular  vaginal  glands. 

7i- 
.7    9.4    22.     -M-      87. 

1.5  mm. 


1.6  2.9  3.5  4-2  3-3 
The  tail  of  the  male  resembles  that  of  the  female  in  form  and  size. 
As  in  the  females,  the  three  caudal  glands  are  found  in  the  anterior  third 
of  the  tail,  and  do  not  extend  materially  farther  forward  than  the  anus. 
The  two  equal,  L-shaped,  slender,  slightly  tapering  brownish  spicula  are  a 
little  longer  than  the  anal  body  diameter.  The  anterior  three-fifths  lie  nearly 
parallel  to  the  body  axis,  while  the  posterior  two-fifths  are  arranged  nearly 
at  right  angles  to  the  body  axis.  The  distal  extremities  of  the  spicula  are 
slightly  widened.  At  their  widest  part,  namely  near  the  proximal  ends,  the 
spicula  are  about  one-eighth  as  wide  as  the  corresponding  portion  of  the 
body.  They  are  very  slightly  narrower  distally  than  proximally,  where  they 
are  barely  cephalated  by  expansion.  The  accessory  piece  is  not  strongly 
developed.  The  main  portion  of  it  lies  parallel  to  the  distal  two-fifths  of  the 
spicula,  and  is  connected  with  the  dorsal  surface  of  the  body  by  means  of 
muscles.  The  ejaculatory  duct  is  one-half  as  wide  as  the  corresponding 
portion  of  the  body.  There  are  two  outstretched  testes.  The  blind  end  of 
the  anterior  testis  is  located  a  short  '  distance  behind  the  nerve-ring,  while 
the  blind  end  of  the  posterior  testis  is  located  about  as  far  in  front  of  the 


66  NORTH    AMERICAN 

anus  as  the  terminus  is  behind  it.    The  testes  are  broad  and  some  parts  appear 
to  fill  up  the  main  portion  of  the  body  cavity. 

Habitat:  Sand  bar  off  Plummer's  Island,  Potomac  River.  Subli- 
mate to  balsam. 

ONCHOLAIMELLUS,  de   Man,   1886. 
Fig.  21,  Plate  VII. 

53 
o    85    18     -M-      QI 

18.     Oncholaimellus  heterurus,  n.sp. —1.2  mm. 

.8     1.5      1.8    1.8         1.4 

The  moderately  thick  layers  of  the  transparent,  naked,  colorless  cuticle 
seem  to  be  destitute  of  markings  of  any  kind.  If  there  are  any  striations 
they  must  be  exceedingly  minute.  The  conoid  neck  becomes  a  little  convex- 
conoid  toward  the  head,  which  is  subtruncated,  and  has  a  lip  region  almost 
imperceptibly  expanded.  There  are  ten  long,  curved,  tapering,  cephalic 
setae,  located  a  trifle  in  front  of  the  middle  of  the  pharynx,  two  lateral,  and 
eight  submedian.  The  members  of  the  submedian  pairs  are  placed  one  in 
front  of  the  other,  the  hinder  members  being  only  about  two-thirds  as  long 
as  the  forward  members.  It  is  the  forward  members  that  are  in  the  same 
circlet  with  the  lateral  setae.  These  latter  are  about  as  long  as  the  longest 
submedian  setae.  The  bases  of  the  lips  are  nearly  as  thick  as  the  wall  of 
the  head,  but  they  gradually  become  quite  thin,  though  the  flaps  are  not  so 
marked  as  they  usually  are  in  Oncholaimus.  There  are  six  lips,  and  each 
bears  on  its  anterior  surface,  near  the  margin  of  the  head,  a  somewhat  out- 
ward pointing,  minute,  innervated  papilla,  which  does  not  very  markedly  in- 
terfere with  the  contour  of  the  front  of  the  head.  The  somewhat  cylindroid 
pharynx  is  about  twice  as  long  as  the  front  of  the  head  is  wide,  and  the 
average  diameter  of  the  cavity  is  a  little  more  than  one-third  of  its  length. 
At  the  middle  the  pharynx  is  about  half  as  wide  as  the  corresponding  por- 
tion of  the  head.  Its  walls  are  fairly  well  chitinized,  and  appear  to  be  des- 
titute of  onchi.  The  description  is  derived  from  a  single  specimen,  in  which 
the  mouth  is  filled  with  detritus,  and  it  is  possible  that  very  minute  teeth 
might  have  escaped  observation,  but  this  does  not  seem  at  all  probable. 
The  bottom  of  the  pharynx  where  it  is  set  on  the  end  of  the  oesophagus,  is 
in  the  shape  of  a  broad,  shallow,  hollow  cone.  At  a  distance  from  the 
anterior  extremity  twice  as  great  as  the  length  of  the  pharynx  the  amphids 
are  seen.  These  are  somewhat  elongated,  roughly  ovate  in  contour,  and 
more  distinctly  marked  anteriorly  than  posteriorly.  The  anterior  border  is 
a  curved,  chitinous  structure  about  one-third  as  wide  as  the  corresponding 
portion  of  the  head.  Slightly  behind  the  anterior  border  the  amphid  has  its 
greatest  diameter.  It  is  about  as  long  as  the  corresponding  radius  of  the 
head,  and  is  extended  backward  by  an  apparently  tubular  structure,  which 
soon  becomes  indefinite.  Viewed  dorso-ventrally  the  amphids  appear  like 
rather  deep  invaginations  of  the  cuticle,  and  each  occupies  fully  half  of  the 


FREE-LIVING   FRESH-WATER   NEMATODES  67 

corresponding  radius  of  the  neck,  and  opposite  them  the  oesophagus  is  a 
trifle  narrower  than  it  is  either  in  front  of  or  behind  them.  The  oeso- 
phagus, which  at  first  is  about  half  as  wide  as  the  base  of  the  head,  con- 
tinues to  have  approximately  the  same  diameter  until  after  it  passes  through 
the  nerve-ring,  which  is  somewhat  in  front  of  the  middle  of  the  neck.  Be- 
hind the  nerve-ring  the  oesophagus  becomes  somewhat  wider,  and  is  finally 
about  two-thirds  as  wide  as  the  base  of  the  neck.  The  lining  of  the  oeso- 
phagus is  a  fairly  distinct  feature.  The  intestine,  which  becomes  at  once 
nearly  three-fourths  as  wide  as  the  body,  is  set  off  from  the  oesophagus  by 
a  distinct  constriction.  There  does  not  appear  to  be  any  well  developed  car- 
dia.  The  cells  composing  the  intestine  contain  scattered  granules,  which 
give  rise  to  a  very  obscure  tessellation,  and  also  contain  doubly  refractive 
granules,  which,  however  are  not  spherical  in  form,  though  their  diameter 
in  different  directions  is  not  very  variable.  The  tail  of  the  male  tapers  rap- 
idly from  the  anus,  so  that  at  the  end  of  the  anterior  fourth  it  has  a 
diameter  but  little  greater  than  that  of  the  terminal  spinneret.  Near  the  an- 
terior end  of  the  cylindrical  part  there  occur  a  pair  of  subventral  arcuate, 
tapering  setae,  which  are  about  as  long  as  the  corresponding  diameter  of 
the  tail.  In  front  of  these  there  is  a  ventrally  submedian  pair  of  papillae, 
and  also  there  is  a  dorsally  submedian  pair  a  little  in  front  of  these  latter. 
The  spinneret  is  of  a  simple  character,  and  has  the  terminus  almost  imper- 
ceptibly swollen.  There  do  not  appear  to  be  any  setae  on  the  spinneret. 
A  trifle  in  front  of  the  proximal  ends  of  the  spicula  there  springs  from  a 
ventrally  submedian  lines  a  somewhat  weakly  developed  bursa,  which  extends 
slightly  beyond  the  body  contour,  but  only  does  this  in  front  of  the  anus. 
It  recedes  into  the  cuticle  at  a  point  slightly  in  front  of  the  caudal  setae. 
This  bursa  does  not  have  any  ribs  and  is  not  striated  in  any  way.  The  two 
equal,  elongated,  rather  uniform,  slightly  cephalated  spicula  are  a  little 
more  than  twice  as  long  as  the  anal  body  diameter,  and  in  their  anterior 
halves  are  nearly  straight.  In  their  posterior  halves  they  are  slightly 
arcuate.  At  the  point  where  they  attain  their  greatest  width  they  are  about 
one-fourth  as  wide  as  the  corresponding  portion  of  the  body.  Seen  dorso- 
ventrally  they  are  somewhat  narrower  and  straighter  than  when  seen  in 
profile.  The  accessory  piece  appears  to  be  compounded  of  a  number  of 
small  chitinous  elements,  the  whole  structure  being  a  little  less  than  one- 
third  as  long  as  the  spicula.  It  is  not  very  strongly  developed,  and  is  not  a 
very  conspicuous  feature.  The  ejaculatory  duct  is  about  half  as  wide  as  the 
corresponding  portion  of  the  body.  There  are  two  testes  outstretched  in 
opposite  directions.  The  blind  end  of  the  anterior  testis  is  about  as  far  be- 
hind the  base  of  the  neck  as  this  latter  is  behind  the  anterior  extremity. 
The  posterior  testis  is  smaller,  but  just  how  much  smaller  is  unknown,  as 
its  blind  end  could  not  be  located  in  the  single  specimen  examined.  Little  or 
nothing  is  known  concerning  the  lateral  fields  and  the  renette. 

Habitat:      Fresh   water   pond,   near   Ocala,   Fla.     Bouin    solution   to 
glycerine. 


68  NORTH    AMERICAN 

Note :  There  is  some  doubt  as  to  whether  this  species  should  be  as- 
signed to  the  genus  Oncholaimellus  for  the  following  reasons:  There  are 
no  pharyngeal  teeth.  The  amphid  varies  somewhat  from  that  of  the  type 
species.  The  spicula  are  of  equal  size,  whereas  in  the  type  species  orie  of  the 
spicula  is  only  half  as  long  as  the  other. 

CEPHALOBUS..  Bastian,  1865. 
Fig.  22,  Plate  VIII. 

5i. 

1 8     15     23      '61         04 
19.     Cephalobus  sub-elongatus,  n.sp.  .6  mm. 

1.6      3.      3-6     4-3        2.1 

The  thin,  transparent,  colorless  layers  of  the  naked  cuticle  are  traversed 
by  about  seven  hundred  plain,  transverse  striae,  resolvable  with  high  powers 
without  very  much  difficulty.  The  conoid  neck  becomes  convex-conoid  to- 
ward the  obscurely  lobed  head,  which  is  rounded  in  front,  and  is  set  off  by 
an  almost  imperceptible,  broad,  exceedingly  shallow  constriction.  There  are 
no  cephalic  setae,  and  no  eye-spots ;  no  amphids  have  been  seen.  There  are 
three  rather  distinct,  bluntly  conoid  lips,  which  are  rounded  in  front,  each 
of  which  apparently  has  two  inconspicuous  innervated  papillae.  The  open 
vestibule  leads  to  a  conoid  pharynx,  which  is  about  one  and  one-half  times 
as  long  as  the  lip  region  is  wide,  and  tapers  from  front  to  back  in  a  com- 
paratively uniform  way.  Between  the  lips  it  has  a  width  about  one-third  as 
great  as  that  of  the  lip  region.  The  posterior  half  of  the  pharynx  rests  in 
the  anterior  end  of  the  oesophagus,  which  enlarges  very  perceptibly,  so  that 
a  little  behind  the  base  of  the  pharynx  it  is  more  than  half  as  wide  as  the 
corresponding  portion  of  the  head.  It  continues  to  have  relatively  much 
the  same  width  until  near  the  middle,  where  it  is  about  three-fifths  as  wide 
as  the  middle  of  the  neck.  There  it  suddenly  diminishes  in  size  so  as  to  be 
only  one-fourth  to  one-fifth  as  wide  as  the  corresponding  portion  of  the 
neck.  Passing  through  the  nerve-ring  with  this  narrow  diameter  it  finally 
enlarges  to  form  an  ellipsoidal  cardiac  bulb  about  two-thirds  as  wide  as  the 
base  of  the  neck,  containing  a  rather  distinct  triplex  but  not  very  complex 
valvular  apparatus  of  the  form  usually  seen  in  this  genus.  There  is  no  very 
definite  cardia.  The  intestine,  which  is  separated  from  the  oesophagus  by 
a  rather  broad  and  shallow  constriction,  is  at  first  only  half  as  wide  as  the 
corresponding  portion  of  the  body.  It  soon  becomes  thicker  walled,  and 
enlarges  so  as  to  be  three-fourths  as  wide  as  the  corresponding  portion  of 
the  body.  It  is  composed  of  cells  of  such  a  size  that  probably  only  about 
two  are  required  to  build  a  circumference.  The  contents  of  the  cells  are  not 
distributed  so  as  to  give  rise  to  anything  distinct  in  the  way  of  tessellation. 
The  posterior  lip  of  the  anus  is  very  slightly  elevated.  From  the  anus  the 
rectum,  which  is  somewhat  longer  than  the  anal  body  diameter,  leads  inward 
and  forward.  The  rectum  is  separated  from  the  intestine  by  a  rather  dis- 
tinct constriction.  The  tail  is  at  first  convex-conoid,  the  convexity  existing 


FREE-LIVING  FRESH-WATER   NEMATODES  69 

almost  entirely  on  the  dorsal  surface.  Through  the  middle  third  the  tail 
tapers  much  more  rapidly  than  elsewhere,  so  that  at  the  beginning  of  the 
posterior  fourth  it  has  a  diameter  no  more  than  one-fifth  as  great  as  at  the 
anus.  Thence  onward  it  is  conoid  to  the  acute  terminus.  There  is  no  spin- 
neret. Very  little  is  known  concerning  the  lateral  fields,  but  at  the  middle 
of  the  body  they  appear  to  be  one-third  as  wide  as  the  corresponding  portion 
of  the  body.  There  do  not  appear  to  be  any  distinct  wings.  The  excretory 
pore  is  located  opposite  the  nerve-ring.  This  latter  surrounds  the  oesophagus 
obliquely,  and  is  accompanied  by  nerve  cells,  of  which  the  greater  number 
are  behind  the  nerve-ring  and  in  front  of  the  cardiac  bulb.  From  the  mas- 
sive elevated  vulva  the  rather  strongly  chitinized,  slightly  colored  vagina 
leads  inward  at  right  angles  to  the  ventral  surface  nearly  half  way  across 
the  body,  where  it  joins  the  single  uterus,  which  extends  forward.  In  speci- 
mens which  do  not  yet  contain  fully  developed  eggs,  and  in  which  the  uterus 
is  occupied  by  spermatozoa,  the  flexure  in  the  sexual  apparatus  occurs  about 
half  way  between  the  vulva  and  the  base  of  the  neck.  The  ovary  extends 
straight  backward,  and  finally  tapers  to  a  blunt  end  a  short  distance  in  front 
of  the  anus.  At  the  rear  end  the  ovary  is  one-half  as  wide  as  the  corre- 
sponding portion  of  the  body.  The  ova  appear  to  be  arranged  more  or  less 
single  file  in  the  greater  part  of  the  ovary,  whose  walls  contain  distinct 
nuclei  of  relatively  large  size.  These  nuclei  are  of  such  a  size  that  about 
six  to  eight  placed  side  by  side  would  reach  across  the  body,  and  are  re- 
moved from  each  other  in  a  longitudinal  direction  a  distance  equal  to  about 
two-thirds  of  the  body  diameter.  None  of  these  cells  could  be  seen  in  that 
portion  of  the  sexual  tube  in  front  of  the  vulva,  and  it  is  surmised  that  the 
cells  composing  the  ovarian  tube  are  markedly  different  in  their  character 
from  those  composing  the  tube  between  the  ovary  and  the  uterus  and  those 
composing  the  wall  of  the  uterus.  The  spermatozoa  have  been  seen  packed  in 
the  uterus  somewhat  like  a  roll  of  coin,  though  each  one  is  thinner  at  the 
margins  than  at  the  center  where  the  nucleus  exists.  The  spermatozoa  are 
of  such  a  size  that  the  uterus  may  contain  about  two  dozen,  arranged  single 
file. 

Habitat :  Moss,  Bog.  W.  End  of  Douglas  Lake,  Mich.  This  species  close- 
ly resembles  C.  elongatus  de  Man,  and  possibly  may  prove  to  be  the  same.  At 
present,  judging  from  a  single  specimen  it  appears  to  differ  in  the  following 
points:  (i)  The  tail  of  the  female  is  of  different  form,  since  that  of  elongatus 
is  nearly  conical ;  (2)  No  wings  have  been  seen  on  sub-elongatus,  while  they 
appear  to  be  a  marked  feature  of  elongatus;  (3)  There  is  no  expansion  of 
the  lip  region  in  elongatus  as  in  sub-elongatus;  (4)  The  vulva  in  sub-elon- 
gatus is  far  more  massive;  (5)  the  pharynx  in  elongatus  is  more  elongated, 
and  longer  as  compared  with  the  length  of  the  head;  (6)  oesophagus  is 
relatively  slenderer  in  elongatus.  Sublimate  to  balsam. 

2.5     15.    31.6      Y      94. 

20.     Cephalobus  setosus,  n.sp.         — -7  mm- 

The  moderately  thick  layers  of  the  naked,  transparent,  colorless  cuticle 
are  traversed  by  425  transverse  striae,  which  are  not  further  resolvable. 


70  NORTH    AMERICAN 

The  striae  are  more  or  less  interrupted  on  the  lateral  fields  by  two  wings, 
or  by  a  single  wing  indicated  by  two  longitudinal  lines.  The  width  of  the 
wing  near  the  middle  of  the  body  is  about  equivalent  to  the  width  of  four 
of  the  annules  of  the  cuticle.  Toward  the  tail  end  the  width  of  the  inter- 
rupted space  is  about  equivalent  to  the  width  of  three  of  the  annules,  and 
near  the  middle  of  the  neck  the  width  is  also  about  equivalent  to  that  of 
three  of  the  corresponding  annules.  Through  the  middle  of  the  lateral  space 
on  which  the  annules  are  interrupted  there  passes  a  longitudinal  refractive 
line.  The  posterior  portion  of  the  neck  is  cylindroid;  the  anterior  half 
conoid  to  the  head,  which  is  not  set  off  in  any  way.  The  lips  are  arranged 
in  two  series:  an  outer  series  of  six  two-parted  lips,  and  an  inner  series  of 
three  obscurely  two-parted  projecting  flaps,  each  armed  at  the  anterior 
rounded  corners  with  short,  arcuate,  tapering,  acute,  forward-pointing 
bristles.  Each  of  the  two  parts  of  the  six  outer  lips  or  appendages  is  con- 
oid and  acute,  and  the  spaces  separating  them  are  much  narrower  than  those 
separating  the  lips  themselves.  At  the  base  of  each  of  the  lateral  two-parted 
lips  there  is  a  transverse  mark,  which  may  possibly  be  the  outer  expression 
of  the  amphid.  This  marking  is  very  minute  and  about  four  times  as  wide 
as  it  is  long,  and  is  placed  transversely  on  the  base  of  the  lip,  iust  in  front 
of  the  foremost  cervical  annule.  It  spans  about  one-sixth  of  the  width  of  the 
head  at  this  point.  The  three  inner  appendages,  which  may  more  properly 
be  termed  the  lips,  are  about  as  long  as  they  are  wide,  and  seem  to  be  flex- 
ible. They  rather  closely  surround  the  mouth  opening.  Each  is  half  as 
wide  again  at  its  free  extremity  as  it  is  at  the  base,  and  the  total  length  is 
about  equal  to  one-fourth  of  the  diameter  of  the  front  of  the  head.  The 
setae  with  which  these  lips  or  flaps  are  armed  are  about  two-thirds  as  long 
as  the  flaps  themselves.  The  rather  obscure,  narrow,  cylindroid  pharynx 
is  about  as  long  as  the  base  of  the  head  is  wide,  and  its  lumen  is  hardly 
wider  than  the  thickness  of  the  cuticle.  The  oesophagus  surrounds  the 
pharynx,  but  is  narrower  in  this  region  than  it  is  immediately  behind  the 
pharynx.  Behind  the  pharynx  it  commences  as  a  tube  about  three-fifths  as 
wide  as  the  base  of  the  head,  and  continues  to  have  about  the  same  diameter 
until  after  it  passes  through  the  nerve-ring.  It  does  increase  a  trifle  in 
diameter,  however,  so  that  at  the  nerve-ring  it  is  about  one-half  as  wide  as 
the  corresponding  portion  of  the  neck.  Some  distance  behind  the  nerve-ring, 
namely,  at  a  distance  about  equal  to  one  and  one-half  diameters  of  the  neck, 
there  is  a  slight  break  in  the  musculature  of  the  oesophagus.  Behind  this 
break  the  oesophagus  begins  to  taper  very  gradually  and  continues  to  de- 
crease in  diameter  until  it  finally  expands  to  form  the  somewhat  ellipsoidal  or 
pyriform  cardiac  bulb,  which  is  about  two-thirds  as  wide  as  the  base  of  the 
neck,  and  contains  a  distinct,  rather  simple,  triple,  chitinized  valvular  appa- 
ratus. That  portion  of  the  oesophagus  immediately  in  front  of  the  cardiac 
bulb  has  a  diameter  about  one-fourth  as  great  as  that  of  the  corresponding 
portion  of  the  neck.  The  lining  of  the  oesophagus  can  be  seen  throughout  its 
length,  and  is  a  fairly  distinct  feature.  The  intestine  which  at  first  is  thin- 


FREE-LIVING  FRESH-WATER   NEMATODES  /I 

walled  is  separated  from  the  oesophagus  by  a  distinct  and  deep  constriction, 
and  becomes  at  once  about  three-fourths  as  wide  as  the  body.  The  anterior 
portion  of  the  intestine  is  characterized  by  the  presence  of  a  considerable  cav- 
ity, which,  however,  soon  narrows,  and,  as  the  internal  wall  of  the  intestine 
is  rather  strongly  refractive,  the  narrow,  sinuous  lumen  is  a  very  conspicuous 
feature.  From  the  rather  conspicuous  depressed  anus  the  rectum,  which  is 
rather  strongly  chitinized  and  somewhat  longer  than  the  anal  body  diameter, 
extends  inward  and  forward.  The  tail  is  somewhat  concave  conoid  from 
the  anus  to  the  very  acute  terminus.  There  are  no  caudal  glands.  The  lat- 
eral fields  appear  to  be  about  one-third  as  wide  as  the  body.  The  nerve- 
ring  surrounds  the  oesophagus  somewhat  squarely.  The  excretory  pore 
appears  to  be  located  near  the  nerve-ring.  The  nature  of  the  internal  sexual 
organs  remains  uncertain,  but  the  vulva  is  evidently  located  near  the  middle 
of  the  body.  The  description  is  derived  from  an  immature  specimen. 

Habitat:  Cranberry  bog,  Arlington  Farm,  Virginia.  Flemming  so- 
lution to  glycerine. 

BASTIANA,  de  Man,  1876. 
Fig.  23,  Plate  VIII. 

.2    8.     18.    58.    89. 
21.     Bastiana  exihs,  n.sp.  — -       1.4  mm. 

•5      -8    i.      i. 5     i.i 

The  moderately  thick  layers  of  the  transparent,  colorless,  naked  cuticle 
are  traversed  by  about  eight  hundred  forty  transverse  striae,  which  do  not 
appear  to  be  further  resolvable.  These  striae  exist  in  the  outer  as  well  as 
inner  cuticle,  so  that  the  entire  contour  of  the  body  is  crenate.  Rather  con- 
spicuous lateral  wings  are  present,  the  optical  expression  of  which  is  two 
distinctly  refractive  longitudinal  lines  opposite  the  lateral  fields,  separated 
from  each  other  by  a  distance  somewhat  greater  than  the  width  of  one  of 
the  annules  of  the  cuticle.  The  gradually  tapering  conoid  neck  ends  in  a 
somewhat  truncate  head,  which  is  not  set  off  in  any  way,  and  which  bears 
a  circlet  of  at  least  six  cephalic  setae,  of  which  four  submedian  are  the 
longer,  and  somewhat  longer  than  the  head  is  wide.  Possibly  each  of  these 
latter  is  accompanied  by  a  shorter  seta,  thus  making  ten  in  all.  Apparently 
labial  papillae  are  present,  but  they  have  not  been  sufficiently  clearly  seen 
to  permit  of  enumeration.  There  is  no  distinct  pharynx.  The  amphids,  lo- 
cated as  in  B.  gracilis  deMan,  are  somewhat  in  the  form  of  the  end  of  a 
shepherd's  crook.  They  are  perhaps  to  be  regarded  as  broad  spiral  bands  of 
about  one  turn.  So  regarded,  the  band  may  be  conceived  to  begin  on  the 
ventral  side  where  its  end  is  rounded  and  its  contour  distinct,  pass  forward, 
and  then  curve  backward  and  end  indefinitely  at  a  point  somewhat  in  the 
rear  of  the  beginning.  The  amphids  are  half  to  two-thirds  as  wide  as  the 
corresponding  portion  of  the  neck,  and  somewhat  longer  than  wide.  There 
are  no  eye-spots.  The  oesophagus  begins  as  a  tube  fully  two-thirds  as  wide 
as  the  head.  It  gradually  increases  in  diameter  as  it  passes  backward,  and  at 


72  NORTH    AMERICAN 

its  posterior  extremity  is  three-fourths  as  wide  as  the  base  of  the  neck. 
There  is  no  definite  cardia.  The  lining  of  the  oesophagus  is  indistinct.  The 
intestine,  which  is  separated  from  the  oesophagus  by  an  obscure  constriction, 
becomes  at  once  three-fourths  as  wide  as  the  body,  is  rather  thick  walled, 
and  its  cells  contain  rather  uniform,  colorless  granules,  not  arranged  in  any 
definite  manner.  From  the  rather  raised  anus  the  conspicuous  rectum,  which 
is  twice  as  long  as  the  anal  body  diameter,  extends  inward  and  forward. 
The  tail  is  conoid,  but  tapers  more  rapidly  near  the  acute  terminus.  A  short 
distance  in  front  of  the  terminus  it  is  nearly  half  as  wide  as  at  the  base. 
Nothing  is  known  concerning  the  renette.  The  lateral  fields  have  not  been 
distinctly  seen,  but  they  appear  to  be  about  one-third  as  wide  as  the  body. 
Nothing  definite  is  known  concerning  the  internal  sexual  organs,  as  the  speci- 
mens examined  were  not  fully  developed. 
60. 

.4    6.      IQ.    -M-    92. 

-  1.4  mm. 
.5     1.2       1.4    2.        1.2 

The  tail  of  the  male  is  like  that  of  the  female  in  form  and  size, 
except  that  the  anus  is  more  prominently  raised.  In  front  of  the  anus 
and  extending  forward  to  the  base  of  the  neck  there  is  a  ventral  row  of 
ninety  supplementary  organs.  These  are  of  small  size,  and  each  ap- 
pears when  seen  in  profile  to  be  a  slight  conical,  innervated  elevation 
having  an  altitude  about  one-third  as  great  as  the  width  of  its  base. 
These  organs  are  removed  from  each  other  a  distance  on  an  average 
about  equal  to  the  radius  of  the  body  or  a  little  more.  They  are  some- 
what nearer  together  posteriorly  than  anteriorly.  Near  the  base  of  the 
neck  the  distance  between  two  adjacent  organs  is  about  equal  to  the 
body  diameter.  The  two  equal,  tapering,  acute,  nearly  straight  spicula 
are  about  one  and  one-third  times  as  long  as  the  anal  body  diameter. 
They  are  slightly  cephalated  by  expansion,  the  cephalum  occupying 
about  one-third  of  the  length.  At  the  widest  part,  namely  in  the  cephala, 
the  spicula  are  one-fourth  to  one-third  as  wide  as  the  corresponding 
portion  of  the  body.  They  do  not  appear  to  have  any  accessory  pieces. 
The  spicula  appear,  when  seen  in  profile,  to  be  arranged  at  an  angle 
of  forty-five  degrees  to  the  body  axis.  Beginning  at  the  anus  and  ex- 
tending obliquely  backward  there  is  a  strand  of  muscle  which  is  at- 
tached to  the  dorsal  side  of  the  body.  The  two  testes  are  outstretched 
in  opposite  directions.  The  blind  end  of  the  anterior  testis  is  about  as 
far  behind  the  base  of  the  neck  as  the  nerve-ring  is  in  front  of  it,  while 
the  blind  end  of  the  posterior  testis  is  about  twice  as  far  in  front  of 
the  anus  as  this  latter  is  in  front  of  the  terminus. 

Habitat:  Fresh  water,  Tynne  Station,  Fla.  Bouin  solution  to  gly- 
cerine. 


FREE-LIVING   FRESH-WATER   NEMATODES  73 

APHANOLAIMUS,  de  Man,  1880. 
Fig.  25,  Plate  VIII. 

43- 
.5    8.8    20.    '50.'        88. 

22.     Aphanolaimus  spinferus,  n.sp.  -    1.5  mm 

.7     1.5      2.1     3.1         1.9 

The  thin,  transparent  layers  of  the  colorless,  naked  cuticle  are  traversed 
by  about  one  thousand  transverse  striae,  which  do  not  appear  to  be  further 
resolvable,  or  at  any  rate  are  resolvable  with  difficulty.  The  cuticle  is  also 
traversed  by  longitudinal  striations,  manifestly  due  to  subcuticular  struc- 
tures,— the  submedian  fields — and  the  attachment  of  the  muscle  cells.  The 
contour  of  the  body  is  minutely  crenate.  There  is  .a  distinct  wing  extending 
throughout  the  length  of  the  body,  whose  presence  is  indicated  by  two  re- 
fractive lines  occupying  a  space  hardly  greater  than  the  width  of  one  of  the 
annules  of  the  cuticle.  On  being  carefully  examined  these  lines  show  traces 
of  the  striations  of  the  cuticle.  The  conoid  neck  ends  in  a  somewhat  rounded 
head,  whose  lip  region  is  set  off  by  a  minute  constriction  just  in  front  of 
the  amphids.  The  contour  of  the  front  of  the  head  is  rounded,  or,  like 
that  of  a  very  flat  truncated  cone.  In  the  midst  of  the  truncation  there  is 
an  exceedingly  minute  depression,  the  mouth  pore.  There  does  not  appear 
to  be  any  very  distinct  pharynx,  but  the  lining  of  the  oesophagus  is  slightly 
altered  in  the  region  of  the  head  back  as  far  as  the  posterior  margins  of  the 
amphids.  It  is  not  unlikely  that  this  represents  a  distinct,  though  rudi- 
mentary pharynx.  The  species,  however,  would  naturally  at  first  sight  be 
classed  as  being  without  a  pharynx.  The  oesophagus  begins  as  a  tube  about 
half  as  wide  as  the  base  of  the  head,  and  expands  very  gradually  until  after 
it  passes  through  the  nerve-ring.  At  the  nerve-ring  its  width  is  about  one- 
third  that  of  the  corresponding  portion  of  the  neck.  Behind  the  nerve-ring 
the  oesophagus  begins  to  expand  a  little  more  rapidly,  though  still  slowly. 
When  it  reaches  the  end  of  the  neck  it  is  half  as  wide  as  the  base  of  the 
neck.  For  a  distance  equal  to  one  body  diameter,  however,  it  decreases  in 
size,  so  that  where  it  joins  the  intestine  it  is  very  narrow,  only  about  one- 
fifth  as  wide  as  the  corresponding  body  diameter.  Nevertheless,  there  ap- 
pears to  be  a  distinct,  though  exceedingly  minute  cardia.  The  lining  of  the 
oesophagus  is  a  fairly  distinct  feature  throughout  its  length.  The  intestine, 
which  is  at  first  thin-walled,  gradually  becomes  half  as  wide  as  the  body,  and 
is  composed  of  cells  of  such  a  size  that  only  two  or  three  are  required  to 
build  a  circumference.  For  the  most  part  the  wall  of  the  intestine  is  moder- 
ately thick.  From  the  very  slightly  raised,  rather  inconspicuous  anus  the 
slender  rectum,  which  is  about  one  and  one-half  times  as  long  as  the  anal 
body  diameter,  extends  inward  and  forward.  It  is  separated  from  the  in- 
testine by  a  very  distinct  and  deep  constriction.  Near  the  middle  the  lateral 
fields  are  about  one-third  as  wide  as  the  body.  The  ventral  gland  is  a  rather 
elongated,  saccate  cell  a  little  longer  than  the  base  of  the  neck  is  wide, 
and  about  one-third  as  wide  as  long.  It  contains  a  large  spherical  nucleus, 


74  NORTH    AMERICAN 

with  a  large,  fairly  distinct  nucleolus.  There  extend  backward  from 
this  cell  two  finger-shaped,  submedian  extensions  nearly  as  long  as  the  cell 
itself.  Notwithstanding  the  distinctness  of  the  organ  and  appendages  the 
position  of  the  excretory  pore  remains  to  be  discovered.  The  tail  tapers 
from  in  front  of  the  anus  in  such  fashion  that  at  the  beginning  of  the 
final  fourth  it  has  a  diameter  about  one-fourth  as  great  as  at  the  anus. 
Thence  onward  the  tail  is  cylindroid  to  the  terminus,  which  bears  a  trun- 
cated, conical,  unarmed  spinneret.  The  three  caudal  glands  are  minute, 
close  together,  opposite  to  and  a  little  behind  the  anus.  From  the  slightly 
depressed  vulva  the  chitinized  vagina  leads  inward  at  right  angles  to  the 
ventral  surface  half  way  across  the  body,  where  it  joins  the  two  symmetrical- 
ly placed  uteri.  The  reflexed  ovaries  reach  about  one-third  the  distance 
back  to  the  vulva  and  contain  a  few  developing  ova  arranged  single  file. 
The  species  is  viviparous.  Two  embryos  and  a  developing  egg  have  been 
seen  in  each  uterus  at  the  same  time.  The  eggs  are  somewhat  elongated, 
about  as  long  as  the  body  is  wide,  and  a  little  less  than  half  as  wide  as  they 
are  long. 

64 

.2    10.     I4.(?)     M      82. 

1.5  mm. 

.7       i.i     2.  2.4      1.9 

The  tail  of  the  male  is  like  that  of  the  female  in  form  and  size.  In 
front  of  the  anus  there  is  a  ventral  series  of  seven  tubular,  protrudable,  sup- 
plementary organs,  occupying  a  space  nearly  equal  to  the  length  of  the  tail. 
The  hindermost  is  opposite  the  proximal  ends  of  the  spicula.  Each  of  these 
organs  is  about  half  as  long  as  the  body  is  wide,  has  its  proximal  end  slightly 
cephalated  by  expansion,  and  its  distal  end  slightly  curved.  The  circular 
apertures  through  which  the  organs  are  protruded  disturb  the  ventral  con- 
tour distinctly,  each  of  them  occupying  a  space  about  equal  to  the  width  of 
four  annules  of  the  cuticle.  There  are  no  special  setae  or  papillae  either  in 
front  of  the  anus  or  behind  it.  The  two  equal,  uniform,  slender,  very 
strongly  arcuate  spicula  are  about  one  and  one-half  times  as  long  as  the 
anal  body  diameter,  and  their  proximal  ends  are  cephalated  by  expansion. 
The  proximal  ends  lie  nearly  opposite  the  body  axis.  There  is  a  simple  ac- 
cessory piece,  applied  for  a  short  distance  to  the  distal  ends  of  the  spicula, 
having  a  backward  pointing  process  two-thirds  as  long  as  the  anal  body 
diameter. 

Habitat:  Potomac  River,  Washington,  D.  C.  Sublimate  to  balsam. 

3i 

23.    Aphanolaimus  minor,  n.sp. — * —    .6  mm. 

•8      3-3      3-9     4-7      2.6 

The  moderately  thin,  transparent  layers  of  the  colorless,  naked  cuticle 
are  traversed  by  fine  transverse  striae,  resolvable  with  moderate  powers, 
and  not  modified  on  the  lateral  fields.  The  presence  of  wings  is  indicated 
by  two  lines  extending  from  near  the  middle  of  the  neck  well  onto  the  tail. 


FREE-LIVING   FRESH- WATER   NEMATODES  75 

These  occupy  a  space  a  little  more  than  the  width  of  one  of  the  annules  of 
the  cuticle,  but  sometimes  one  of  these  lines  is  more  prominent  than  the 
other.  The  conoid  neck  ends  in  a  rounded  head,  which  is  not  set  off  in  any 
way.  There  are  no  cephalic  setae.  There  does  not  appear  to  be  any  distinct 
pharynx.  The  lining  of  the  oesophagus  is  slightly  modified  back  twice  as 
far  as  the  posterior  margins  of  the  amphids,  and  very  likely  this  portion  of 
the  tube  may  be  regarded  as  a  narrow  rudimentary  pharynx.  Twice  as  far 
from  the  anterior  extremity  as  the  base  .of  this  supposed  pharynx  the 
oesophagus  is  distinctly  interrupted  by  a  break  in  the  musculature,  although 
there  is  no  change  in  size,  and  just  behind  this  break  there  are  three  distinct, 
elongated  nuclei,  one  in  each  segment  of  the  oesophagus.  These  appear- 
ances are  reminiscent  of  the  arrangement  in  Plectus,  to  which  Aphanolaimus 
is  doubtless  related.  There  do  not  appear  to  be  any  distinct  lips,  though 
possibly  there  may  be  three  exceedingly  minute,  well  amalgamated,  flattish 
ones.  Although  at  first  glance  the  amphids  appear  to  be  circular,  they  are 
really  spiral  in  form.  They  are  about  one-fifth  as  wide  as  the  corresponding 
portion  of  the  neck.  Their  distance  from  the  anterior  extremity  is  about 
equal  to  the  diameter  of  the  head;  or  in  other  words,  their  centers  are  re- 
moved from  the  anterior  extremity  a  distance  about  twice  as  great  as  their 
diameter.  The  amphids  appear  to  be  slightly  larger  in  the  male  than  in  the 
female.  There  are  no  eye-spots.  The  oesophagus  begins  at  the  base  of  the 
above  described  pharynx,  as  a  tube  about  half  as  wide  as  the  corresponding 
portion  of  the  neck.  It  widens  very  gradually,  so  that  where  it  passes 
through  the  nerve-ring  it  is  nearly  one-third  as  wide  as  the  corresponding 
portion  of  the  neck.  At  the  middle,  nearly  opposite  the  nerve-ring,  there 
is  an  almost  imperceptible  increase  in  diameter,  indicative  of  a  deteriorated 
median  swelling.  Finally,  it  expands  into  the  narrowly  pyriform  cardiac 
swelling  destitute  of  any  distinct  valvular  apparatus.  This  swelling  is  half 
to  two-thirds  as  wide  as  the  base  of  the  neck.  The  lining  of  the  oesophagus 
is  a  distinct  feature  throughout  its  length.  There  is  no  distinct  cardia.  The 
intestine,  which  is  at  first  only  one-fifth  as  wide  as  the  base  of  the  neck, 
joins  the  middle  of  the  posterior  surface  of  the  cardiac  swelling.  It  is 
moderately  thick-walled,  and  gradually  becomes  about  two-thirds  as  wide  as 
the  body.  It  appears  to  be  made  up  of  cells  of  such  a  size  that  few,  prob- 
ably two  or  three,  or  possibly  four,  are  required  to  build  a  circumference. 
The  body  tapers  gradually  from  a  long  distance  in  front  of  the  anus.  This 
latter  is  very  slightly  raised,  more  particularly  on  the  anterior  margin.  From 
it  the  rectum,  which  is  about  as  long  as  the  anal  body  diameter,  extends  in- 
ward and  forward.  The  tail  is  conoid  in  the  anterior  three-fourths.  The 
posterior  fourth  is  cylindrical  and  has  a  diameter  nearly  one-third  as  great 
as  that  of  the  base  of  the  tail.  It  ends  in  a  rounded,  unarmed  spinneret,  bear- 
ing an  apiculum.  The  lateral  fields  appear  to  be  about  one-third  as  wide  as 
the  body.  The  nerve-ring  surrounds  the  oesophagus  somewhat  obliquely. 
There  appears  to  be  a  small  renette  cell  opposite  the  anterior  portion  of 
tire  intestine,  but  the  position  of  the  excretory  pore  has  not  been  discovered. 


76  NORTH    AMERICAN 

From  the  inconspicuous  vulva  the  vagina  leads  inward  at  right  angles  to  the 
ventral  surface  about  half  way  across  the  body,  where  it  joins  the  two  sym- 
metrically-placed uteri.  The  reflexed  ovaries  reach  about  half  way  back 
to  the  vulva  and  contain  half  a  dozen  or  more  developing  ova  arranged 
somewhat  irregularly.  The  thin-shelled,  ellipsoidal  eggs  are  about  as  long 
as  the  body  is  wide  and  about  three-fifths  as  wide  as  long.  They  have  been 
seen  in  the  uterus  one  at  a  time,  and  apparently  are  deposited  before  seg- 
mentation begins. 

3.     15.    23.    -M-    85. 

.5  mm. 

1.8    3.4    3.8   4-2       34 

The  tail  of  the  male  is  conoid  in  the  anterior  three-fourths  in  such 
fashion  that  the  beginning  of  the  final  fourth  has  a  diameter  of  about  one- 
eighth  that  of  the  base  of  the  tail ;  thence  onward  the  tail  is  nearly  cylin- 
drical or  expands  slightly,  and  ends  in  a  rounded  terminus  bearing  an  api- 
culum  forming  an  unarmed  spinneret.  The  caudal  glands  are  located  in  the 
base  of  the  tail.  In  front  of  the  anus  in  the  male  there  is  a  ventral  row  of 
eight  or  nine  protrudable.  obscurely  S-shaped,  yellowish  supplementary  or- 
gans. These  appear  to  be  of  rather  uniform  size  and  are  equally  spaced. 
Their  length  is  somewhat  greater  than  that  of  the  radius  of  the  body,  and 
they  are  placed  at  an  angle  of  about  thirty  degrees  to  the  body  axis.  They 
are  of  rather  uniform  diameter  throughout  their  length,  but  taper  a  little 
toward  the  blunt  distal  extremity,  and  are  obscurely  cephalated  at  the 
proximal  ends.  The  distal  extremity  of  the  hindermost  of  these  organs  is 
located  nearly  opposite  the  proximal  ends  of  the  spicula.  The  entire  distance 
occupied  by  the  series  is  about  one  and  one-half  times  as  great  as  the  length 
of  the  tail.  The  two  equal,  tapering,  strongly  arcuate,  brownish  yellow  spicula 
are  about  one  and  one-half  times  as  long  as  the  anal  body  diameter.  Their 
proximal  ends  are  cephalated  by  expansion,  and  extending  from  the  proximal 
ends  toward  the  distal  extremities  there  are  straight,  refractive  lines  indicat- 
ing possibly  that  there  is  more  to  the  framework  of  the  spicula  than  appears 
at  first  glance.  The  spicula  curve  inward  and  backward  to  near  the  dorsal 
side  of  the  tail,  and  then  pass  forward  so  that  their  proximal  extremities  lie 
opposite  the  body  axis.  The  spicula  are  accompanied  by  a  rather  straight, 
slender,  slightly  tapering,  blunt  accessory  piece  applied  to  their  distal  fifths. 
From  this  point  the  accessory  piece  extends  inward  and  backward  at  an 
angle  of  sixty  degrees,  and  ends  a  little  to  the  dorsal  side  of  the 
body  axis.  At  their  widest  part,  just  behind  the  cephala,  the  spicula 
have  a  width  about  one-fifth  as  great  as  that  of  the  corresponding  portion  of 
the  body.  A  little  behind  the  middle  of  the  tail  there  are  two  ventrally  sub- 
median  setae,  about  half  as  long  as  the  corresponding  diameter  of  the  tail. 
The  ejaculatory  duct  is  about  one-third  as  wide  as  the  body.  There  are  two 
testicles,  one  extending  forward  and  the  other  backward.  The  blind  end  of 
the  anterior  testicle  is  a  little  farther  behind  the  base  of  the  neck  than  the 


FREE-LIVING   FRESH-WATER   NEMATODES  77 

nerve-ring  is  in  front  of  it.    The  blind  end  of  the  posterior  testicle  lies  just 
in  front  of  the  anterior  supplementary  organ. 

Habitat:     Mud,  Potomac  River.     Sublimate  to  balsam. 

TYLENCHUS,   Bastian,   1865. 

60 

24.     Tylenchus  symmetries,  n.sp.   2-7     108    17.    -49-    90.2          mm 

i-4      2.8      3.3    3.8       2.7 

The  moderately  thick  layers  of  the  transparent,  colorless,  naked  cuticle 
are  traversed  by  fine  plain  transverse  striae,  which  are  not  further  resolvable. 
There  are  two  wings  on  the  lateral  fields,  removed  from  each  other  a  dis- 
tance about  equal  to  one-fourth  to  one-fifth  the  body  diameter.  The  space 
between  these  wings  is  very  faintly  marked  with  longitudinal  lines,  of  which 
two  near  the  middle  are  more  prominent  than  the  others.  The  wings  them- 
selves bear  traces  of  transverse  striation.  These  wings  begin  near  the 
middle  of  the  neck  and  end  on  the  tail.  The  conoid  neck  becomes  convex- 
conoid  toward  the  somewhat  rounded  head,  which  is  not  set  off,  or  at  least 
only  by  an  almost  imperceptible  constriction  a  short  distance  behind  the  lip 
region.  There  are  no  distinct  lips.  What  appear  to  be  the  faintest  possible 
traces  of  papillae  may  be  seen  on  the  lips,  but  these  do  not  disturb  the  rounded 
contour  of  the  head.  Were  it  not  for  the  innervations  it  would  be  prac- 
tically impossible  to  see  them.  The  pharynx  is  tubular  and  just  wide  enough 
to  make  a  passage  for  the  spear.  This  latter  is  slender,  nearly  one  and  one- 
half  times  as  long  as  the  base  of  the  head,  and  has  a  three-bulbed  base  about 
one-fifth  to  one-fourth  as  wide  as  the  corresponding  portion  of  the  head. 
Near  the  middle  the  spear  is  closely  surrounded  by  a  rather  inconspicuous 
guiding-ring  or  cylinder,  about  one-fourth  as  long  as  the  spear.  At  its 
widest  part,  namely,  in  the  proximal  half,  the  diameter  of  the  spear  is  less 
than  the  width  of  two  of  the  adjacent  annules  of  the  cuticle.  The  oesophagus 
begins  as  a  tube  about  one-third  as  wide  as  the  base  of  the  head,  and  con- 
tinues to  have  this  diameter  until  it  expands  to  form  the  ellipsoidal  or  pro- 
late median  bulb.  This  latter  is  about  three-fifths  to  two-thirds  as  wide  as 
the  middle  of  the  neck,  and  contains  a  distinct  ellipsoidal  valvular  apparatus 
about  one-fifth  as  wide  as  the  bulb  itself.  Behind  the  median  bulb  the 
oesophagus  is  smaller  than  elsewhere.  For  a  distance  equal  to  twice  the 
width  of  the  neck  it  has  a  width  only  about  one-eighth  to  one-sixth 
as  great  as  that  of  the  corresponding  portion  of  the  neck.  There- 
after, it  expands  to  form  the  elongated-pyriform  non-muscular  cardiac  swell- 
ing, which  is  half  as  wide  as  the  base  of  the  neck,  and  contains  a  rather 
conspicuous  nucleus.  The  lining  of  the  oesophagus  is  a  fairly  distinct  feature 
in  its  anterior  part;  but  posteriorly  it  is  much  less  distinct,  and  is  very  diffi- 
cult to  observe  in  the  cardiac  swelling.  The  intestine,  which  is  separated 
from  the  oesophagus  by  an  indistinct  constriction,  becomes  at  once  fully  two- 
thirds  as  wide  as  the  body.  Its  cells  are  packed  with  large  granules  of  some- 
what variable  size,  the  largest  of  which  have  a  diameter  about  one-eighth  as 
great  as  that  of  the  body,  the  smallest  being  considerably  smaller.  These 


78  NORTH    AMERICAN 

granules  are  so  prominent  as  to  obscure  the  cellular  structure  of  the  in- 
testine. From  the  very  slightly  elevated  and  rather  inconspicuous  anus  the 
rectum,  which  is  hardly  as  long  as  the  anal  body  diameter,  extends  inward 
and  forward.  The  tail  is  conoid  to  the  terminus,  where  it  rather  suddenly 
tapers  much  more  rapidly  to  a  very  acute  point.  This  rapidly  tapering  por- 
tion has  a  length  about  equal  to  one-fourth  the  anal  body  diameter,  and  the 
diameter  at  the  point  where  the  change  in  taper  begins  is  about  equal  to  one- 
fifth  of  the  anal  body  diameter.  The  lateral  fields  appear  to  be  a  little  more 
than  one-third  as  wide  as  the  body.  The  nerve-ring  surrounds  the  oesopha- 
gus obliquely.  The  excretory  pore  is  located  a  little  behind  the  nerve-ring,  a 
little  more  than  half  way  from  the  base  of  the  neck  to  the  middle  of  the 
median  bulb.  From  the  slightly  elevated,  rather  massive  vulva  the  vagina 
leads  inward  at  right  angles  to  the  ventral  surface  nearly  half  way  across 
the  body,  where  it  joins  the  two  uteri.  Apparently  the  ovaries  are  out- 
stretched. A  single  egg  has  been  seen  in  one  of  the  uteri.  It  is  about  twice 
as  long  as  the  body  is  wide  and  about  one-third  as  wide  as  long.  It  is  thin- 
shelled  and  apparently  undergoes  segmentation  before  being  deposited. 

3.1     13.5    20.5    -M3   89.1 


2.2        3.6        3.9       4.2        3.2 

The  tail  of  the  male  is  like  that  of  the  female  in  form.  From  the  raised 
anus  it  is  arcuate-conoid  to  the  terminus,  which  is  concave-conoid  and  ends 
in  an  exceedingly  fine  slender  point.  The  length  of  the  terminus  is  about 
one-third  as  great  as  the  anal  body  diameter,  while  its  diameter  is  about 
one-fourth  as  great  as  the  anal  body  diameter.  There  are  no  supplementary 
organs,  nor  have  any  special  papillae  been  seen  either  in  front  of  the  anus 
or  behind  it.  There  is  a  fairly  well  developed,  but  not  very  prominent  bursa, 
which  extends  but  little  beyond  the  ventral  contour  at  any  point.  It  springs 
from  the  submedian  lines  at  a  distance  as  far  in  front  of  the  anus  as  the 
middle  of  the  tail  is  behind  it.  The  bursa  is  striated  like  the  cuticle,  and  its 
margin  is  entire;  it  extends  to  near  the  end  of  the  tail.  Near  the  middle 
of  the  tail  there  appears  to  be  a  bursal  rib  on  each  side,  which  does  not 
reach  to  the  margin  of  the  bursa.  The  ejaculatory  duct  is  about  one-third 
as  wide  as  the  body.  The  blind  end  of  the  single  outstretched  testicle  lies 
a  short  distance  behind  the  base  of  the  neck. 

Habitat  :  Marsh  in  black  clay  with  much  decayed  vegetation,  near  Im- 
patiens,  Arlington  Farm,  Virginia.  Flemming  solution  to  glycerine. 

RHABDITIS,   Dujardin,   1845. 

7i 

1.2     10.8    16.8    '55'    93.8 

25.     Rhabditis  punctata,  n.sp.         -       1.8  mm. 

1.2      3.3      4.3     4.9      1.6 

The  thin  layers  of  the  transparent,  naked,  colorless  cuticle  are  traversed 
by  transverse  striae,  which  are  resolvable  with  high  powers  and  appear  to  be 
resolvable  into  rows  of  dots,  but  there  is  some  doubt  about  this.  The  cuticle 


FREE-LIVING  FRESH-WATER   NEMATODES  79 

is  longitudinally  striated.  Near  the  middle  of  the  male  there  is  a  lateral  area 
nearly  half  as  wide  as  the  body,  which  is  nearly  destitute  of  striations.  On 
either  side  of  this  field  the  cuticle  may  be  seen  with  high  powers  to  be  dis- 
tinctly longitudinally  striated.  This  lateral  field  narrows  toward  both  ex- 
tremities so  as  to  be  hardly  wider  than  the  spicula,  so  that  the  main  portion 
of  the  cuticle  of  these  regions  appears  there  to  be  longitudinally  striated. 
The  neck  is  conoid,  becoming  almost  imperceptibly  convex-conoid  toward 
the  head,  which  is  somewhat  rounded  and  bears  six  lips,  which  are  fairly 
well  separated  from  each  other,  and  each  of  which  appears  to  be  papillate. 
The  simple,  unarmed  pharynx  is  cylindrical  and  one-third  as  wide  as  the 
base  of  the  head.  Its  cavity  is  four  to  five  times  as  long  as  wide.  No  amphids 
have  been  seen,  and  there  are  no  eye-spots.  The  oesophagus  receives  the 
base  of  the  pharynx  and  becomes  at  once  about  two-thirds  as  wide  as  the 
base  of  the  head.  It  continues  to  have  this  diameter  until  it  expands  to 
form  the  ellipsoidal  median  swelling,  which  has  a  distinctly  radiated  fibrous 
structure.  This  swelling  is  about  two-thirds  as  wide  as  the  corresponding 
portion  of  the  neck,  and  is  separated  from  the  portion  of  the  oesophagus 
preceding  it,  as  well  as  the  portion  succeeding  it,  by  a  refractive  division  in 
the  internal  musculature.  Behind  the  median  swelling  the  oesophagus  has 
a  diameter  less  than  half  as  great  as  that  of  the  corresponding  portion  of 
the  neck,  and  it  narrows  continuously  until  it  reaches  the  pyriform  cardiac 
bulb,  which  is  three-fourths  as  wide  as  the  base  of  the  neck  and  contains  a 
well  developed,  complicated,  chitinous  valvular  apparatus  half  as  wide  as 
the  bulb  itself.  There  is  no  distinct  cardia.  The  somewhat  transparent  and 
colorless  intestine,  which  is  separated  from  the  oesophagus  by  a  distinct 
constriction,  is  composed  of  cells  containing  scattered  granules  of  variable 
size,  the  largest  of  which  have  a  diameter  somewhat  less  than  the  thickness 
of  the  cuticle,  and  the  smallest  of  which  are  very  much  smaller.  The  anus 
is  slightly  raised,  and  from  it  the  rectum,  which  is  one  and  one-half  times  as 
long  as  the  anal  body  diameter,  leads  almost  directly  forward.  The  body 
tapers  for  some  distance  in  front  of  the  anus;  from  the  anus  onward  it  is 
conical  to  the  acute  terminus.  There  is  no  spinneret,  and  there  are  no  caudal 
glands.  Nothing  definite  is  known  concerning  the  renette  cell.  The  excre- 
tory pore  is  located  about  half  way  between  the  median  and  posterior  bulbs, 
just  behind  the  oblique  nerve-ring.  The  two  uteri  extend  in  opposite  direc- 
tions, and  the  ovaries  are  reflexed,  the  flexures  occurring  the  one  not  far 
behind  the  base  of  the  neck  and  the  other  not  far  in  front  of  the  anus. 
The  mature  females  contain  scores  of  eggs  in  various  stages  of  development, 
the  most  advanced  containing  well-developed  embryos. 

63 
2.3    16.2    25.9    -M    96.3 

i.  mm. 

i-9      34      3-5     3-7      2.6 

The  tail  of  the  male  is  conoid  from  the  anus  in  such  fashion  that  at  the 
beginning  of  the  posterior  third  it  has  become  reduced  to  a  mere  striated 
nearly  straight  spine,  which  is  no  wider  than  one  of  the  ribs  of  the  bursa. 


8O  NORTH   AMERICAN 

The  dorsal  contour  of  the  tail  continues  as  a  more  or  less  regular  extension 
of  that  of  the  body.  The  ventral  contour,  however,  is  elevated  at  the  anus; 
at  any  rate,  when  the  spicula  are  partly  extruded.  This  elevation  appears  to 
be  largely  median,  and  there  is  a  distinct  groove  on  either  side  between  it  and 
the  bursa.  When  this  groove  is  brought  into  optical  section  and  the  anal 
elevation  is  disregarded  the  tail  appears  to  be  asymmetrically  conoid.  The 
two  equal,  brownish,  nearly  straight  spicula  are  fully  twice  as  long  as  the 
tail,  or  one  and  one-half  times  as  long  as  the  body  diameter,  measured  oppo- 
site the  proximal  ends  of  the  spicula.  The  spicula  in  the  distal  three-fourths 
taper  to  a  blunt  point.  At  their  widest  part,  considerably  in  front  of  the 
middle,  they  are  one-fourth  to  one-fifth  as  wide  as  the  corresponding  portion 
of  the  body.  In  the  proximal  fourths  the  spicula  are  rather  suddenly  nar- 
rowed and  terminate  in  bulbs  or  cephala,  which  have  a  diameter  twice  as 
great  as  the  portion  of  which  they  are  expansions.  Parallel  to  the  spicula 
there  are  accessory  pieces.  These  are  two-thirds  to  three-fourths  as  long  as 
the  spicula,  which  they  partially  envelop.  They  are  about  as  strongly  chitin- 
ized  as  the  spicula  themselves.  The  transparent,  colorless  bursa  springs 
from  the  submedian  lines,  nearly  opposite  the  proximal  ends  of  the  spicula, 
and  when  seen  in  profile  only  slightly  exceeds  the  ventral  contour  in  front 
of  the  anus,  but  behind  the  anus  exceeds  the  ventral  contour  of  the  tail 
proper  so  much  that  nearly  the  entire  length  of  the  ribs  comes  plainly  into 
view.  The  ribs  are  arranged  in  three  groups:  (i)  Two  ribs  close  together 
opposite  the  middle  of  the  spicula.  (2)  Four  ribs  close  together  opposite  to, 
and  a  trifle  behind  the  anus.  (3)  Four  ribs  of  which  three  are  very  close 
together,  and  one  a  little  farther  forward,  the  whole  group  being  opposite 
the  middle  of  the  tail.  Most  of  these  ribs  reach  to  the  margin  of  the  bursa, 
which  is  entire  and  is  not  distinctly  striated.  The  outer  members  of  the 
middle  and  posterior  groups  do  not  reach  quite  to  the  margin.  The  ejacu- 
latory  duct  is  nearly  one-half  as  wide  as  the  body.  The  single,  outstretched 
testicle  has  its  blind  end  located  about  half  as  far  behind  the  base  of  the 
neck  as  this  latter  is  behind  the  anterior  extremity.  At  its  blind  end  the 
testicle  is  about  one-third  as  wide  as  the  body.  It  gradually  increases  in 
width,  so  that  it  occupies  four-fifths  of  the  diameter  of  the  middle  of  the 
body.  The  spermatocytes  are  of  large  size,  one-third  to  one-half  as  wide 
as  the  body. 

Habitat :     About  the  roots  of  aquatic  plants,  Potomac  River,  Washing- 
ton, D.  C. 

TRILOBUS,  Bastian,  1865. 

Fig.  15,  Plate  VI. 

40 

26.     Trilobus  longus,  (Leidv),  Bastian^— *9'     46'     ^    1.2  mm. 

2.      2.8      3.8     4.6     2.3 

The  thin,  transparent  layers  of  the  colorless  cuticle  are  traversed  by 
exceedingly  fine  plain  transverse  striae,  more  particularly  visible  in  the 


FREE-LIVING  FRESH-WATER   NEMATODES  8l 

lower  layers  with  high  powers.  There  are  short  hairs  to  be  found  here 
and  there  on  the  surface  of  the  body,  more  particularly  toward  the  ex- 
tremities. The  conoid  neck  ends  in  a  somewhat  rounded  head  not  set 
off  by  any  constriction.  The  cephalic  setae  appear  to  be  ten  in  number 
(eight  submedian  and  two  lateral),  outward  pointing,  each  about  one- 
sixth  as  long  as  the  head  is  wide,  and  placed  on  the  outer  margin  of  the 
front  of  the  head  opposite  the  posterior  portion  of  the  pharynx.  The 
members  of  the  submedian  pairs  are,  however,  of  unequal  size.  There 
are  six  small,  pointed  lips  surrounding  the  mouth  opening.  It  is  cer- 
tain that  these  lips  bear  papillae,  but  the  number  is  not  known.  Lat- 
eral organs  in  the  form  of  somewhat  stirrup  shaped  markings  one- 
fourth  as  broad  as  the  corresponding  portion  of  the  head,  occur  at  a 
short  distance  behind  the  base  of  the  rudimentary  pharyngeal  cavity. 
This  latter  is  a  more  or  less  triquetrous  cyathiform  cavity  having  its 
walls  distinctly  chitinized  and  bearing  at  its  base  one  or  more  protuber- 
ances near  the  point  where  the  lumen  of  the  oesophagus  begins.  One 
of  these  is  a  ridge,  the  others  minute  teeth.  The  average  width  of  the 
main  pharyngeal  cavity  is  about  one-third  that  of  the  head.  The  oeso- 
phagus is  slightly  expanded  to  receive  the  pharynx,  but  otherwise  be- 
gins as  a  tube  about  three-fifths  as  wide  as  the  anterior  part  of  the 
neck,  and  expands  very  gradually  to  the  end,  where  it  is  a  little  more 
than  half  as  wide  as  the  base  of  the  neck.  The  lining  of  the  oeso- 
phagus is  a  distinct  feature  throughout  its  length.  There  is  a  distinct 
rounded  cardia.  The  intestine,  which  becomes  at  once  about  two-fifths 
as  wide  as  the  body,  is  separated  from  the  oesophagus  by  a  distinct 
constriction,  in  which  lie  the  three  granular  bodies  whose  presence 
gave  origin  to  the  name  of  the  genus.  The  intestine  is  relatively  thick 
walled,  its  small  cells  containing  scattered  granules  of  small  size,  which 
are  not  arranged  in  any  very  definite  manner.  The  intestine  frequently 
contains  diatoms  in  large  numbers,  thus  indicating  that  these  are  a 
common  source  of  nourishment  for  this  species.  From  the  slightly  de- 
pressed anus  the  rectum,  which  is  about  as  long  as  the  anal  body 
diameter,  extends  inward  and  forward  to  join  the  intestine,  which  is 
narrowed  at  its  extremity  so  as  to  be  about  two-fifths  as  wide  as  the 
body.  Nothing  is  known  concerning  the  ventral  gland.  The  longi- 
tudinal fields  are  distinctly  developed,  being  about  one-fourth  as  wide 
as  the  worm  itself.  The  nerve-ring  surrounds  the  oesophagus  some- 
what obliquely.  The  tail  is  conoid  in  the  anterior  third  in  such  fashion 
that  at  the  beginning  of  the  middle  third  it  has  a  diameter  about  one- 
fourth  as  great  as  at  the  anus.  Thence  onward  it  tapers  gradually  to 
the  slightly  swollen  spinneret  or  outlet  for  the  caudal  glands.  These 
latter,  three  in  number,  are  located  tandem  in  the  tail  opposite  to  and 
slightly  behind  the  anus.  From  the  slightly  elevated  vulva  the  vagina 
leads  inward  at  right  angles  to  the  ventral  surface  fully  half  way 
across  the  body.  The  vagina  is  bifurcated  and  extends  in  opposite  di- 


82  NORTH    AMERICAN 

rections,  the  reflexed  ovaries  passing  about  two-thirds  the  way  back  to 
the  vulva.  Two  or  three  eggs  may  occur  in  each  uterus  at  one  time. 
These  are  somewhat  ellipsoidal  and  thin  shelled,  being  about  two-thirds 
as  long  as  the  body  is  wide  and  about  two-thirds  as  wide  as  long.  The 
eggs  appear  to  indicate  at  least  the  early  stages  of  segmentation  before 
being  deposited.  The  walls  of  the  vagina  present  the  peculiarity  of  being 
very  thick,  and  composed  of  concentric  layers  to  the  number  of  six  or 
seven,  so  that  the  organ  is  considerably  broader  than  it  is  deep.  Its  in- 
ternal wall  presents  the  peculiarity  of  staining  strongly  with  carmine. 
1.3  8.3  137  -M-  92.  ^  ^ 

2.         2.6        3.2         3.8        2.7 

The  tail  of  the  male  is  very  much  like  that  of  the  female  in  form 
and  size.  Supplementary  organs  are  found  in  front  of  the  anus  only. 
These  are  six  in  number,  of  which  three  are  very  prominent.  The  an- 
terior member  of  this  group  of  three  is  about  twice  as  far  in  front  of 
the  anus  as  the  spinneret  is  behind  it.  The  members  of  this  group  are 
equidistant,  the  distance  between  consecutive  members  being  about  twice 
as  great  as  the  diameter  of  the  organs  themselves.  All  three  occupy 
a  distance  about  twice  as  great  as  the  corresponding  body  diameter. 
Each  of  these  organs  consists  of  an  internal  and  an  external  portion,  the 
internal  portion  being  a  flattish,  hemispherical  mass  of  tissue  of  very 
fine,  or  at  least  uniform  texture.  These  have  a  diameter  about  two- 
fifths  as  great  as  that  of  the  body  at  the  same  part.  The  external 
portion  of  these  organs  consists  of  a  ring  slightly  raised,  from  which 
projects  a  mammiform  papilla  which  bears  a  minute  median  seta  or 
nerve-ending.  When  this  mammiform  portion  is  traced  inward  it  passes 
through  the  ring  on  the  surface  of  the  body  and  then  bends  forward 
and  ends  rather  indefinitely  in  the  anterior  contour  of  the  internal  por- 
tion of  the  organ.  These  organs  possess  the  peculiarity  of  staining 
strongly  with  carmine.  In  addition  to  the  organs  already  described 
there  are  three  others  of  smaller  size,  two  very  minute,  one  near  the 
anus  and  the  other  opposite  the  proximal  portions  of  the  spicula.  The 
third,  which  has  a  size  intermediate  between  those  just  described  and 
those  first  described,  is  located  about  half  way  between  the  anus  and 
the  posterior  member  of  the  larger  group.  These  smaller  organs  are 
comparatively  close  counterparts  of  the  larger,  differing  merely  in  size. 
In  addition  it  may  be  noted  that  the  cuticle  on  the  ventral  surface  of 
the  male  throughout  this  region  of  the  body,  that  is,  as  far  forward  as 
the  most  anterior  of  these  organs,  bears  about  twenty  exceedingly 
minute  structures  on  the  ventral  line,  which  appear  to  be  innervated 
papillae.  These  also  stain  strongly  with  carmine,  although  they  are  so 
minute  as  to  be  difficult  to  observe.  There  are  no  papillae  on  the  tail, 
but  there  are  several  short  hairs,  more  particularly  near  the  ventrally 
submedian  lines.  There  is  no  bursa.  The  ejaculatory  duct  is  coexten- 
sive with  the  supplementary  organs.  It  is  on  the  average  nearly  half 


FREE-LIVING  FRESH-WATER   NEMATODES  83 

as  wide  as  the  corresponding  portion  of  the  body.  It  is  connected  with 
the  seminal  vesicle  by  a  narrow  portion.  The  seminal  vesicle  is  elon- 
gated, about  half  as  wide  as  the  body,  and  extends  to  a  point  about  as 
far  behind  the  neck  as  the  base  of  the  neck  is  from  the  anterior  ex- 
tremity. From  this  point  the  two  nearly  equal  testicles  extend  in  oppo- 
site directions,  and  end  blind,  one  not  far  behind  the  base  of  the  neck, 
and  the  other  not  far  from  the  middle  of  the  body.  These  possess  the 
peculiarity  of  being  slightly  swollen  at  their  proximal  ends  just  where 
they  join  the  vesicle.  These  swellings  appear  to  constitute  veritable 
cavities  of  small  size.  That  region  of  the  body  corresponding  to  the 
ejaculatory  duct  is  traversed  by  oblique  striae,  which,  however,  are  ar- 
ranged at  right  angles  to  the  direction  of  such  oblique  striations  as 
are  found  in  other  genera,  and  it  is  probable  that  they  are  connected  with 
the  duct  itself,  and  are  not  muscles  of  the  character  which  usually  give 
rise  to  these  oblique  striations  on  the  males  of  other  genera.  The  two 
equal,  arcuate  slender  spicula  appear  to  be  of  rather  uniform  diameter 
when  viewed  laterally,  and  are  one  and  one-half  times  as  long  as  the 
anal  body-diameter.  Their  proximal  ends  are  cephalated  by  contrac- 
tion. They  are  accompanied  by  accessory  pieces  two-fifths  as  long  as 
the  spicula  themselves,  and  arranged  parallel  to  the  distal  portions  of 
the  spicula. 

Habitat:  Mud,  about  the  bases  of  aquatic  plants,  Potomac  river, 
D.  C. 

MESOMERMIS,  Dady. 
Fig.  18,  Plate  VII.    Fig.  24,  Plate  VIII. 

55 
0-      ,,  .8    6.3     ii.    -M-    96. 

27.     Mesomermis  virgimana,  n.sp.    1.8  mm. 

1.3    2.        1.8  2.3       2.2 

The  rather  thick,  transparent,  colorless  layers  of  the  naked  cuticle 
are  destitute  of  transverse  striations.  There  are  minute  longitudinal 
striations  throughout  the  body.  These  are  interrupted  on  the  lateral 
lines,  where  there  is  a  distinct  wing.  The  conoid  neck  becomes  convex- 
conoid  toward  the  lip  region,  which  is  not  set  off  in  any  way.  There 
are  no  cephalic  setae,  and  there  is  no  distinct  pharynx.  The  mouth 
pore  is  very  minute,  and  is  a  little  toward  the  ventral  side  of  the  middle 
of  the  front  of  the  head.  The  cuticle  has  about  the  same  thickness  on 
the  head  as  elsewhere,  being  only  a  trifle  thicker.  The  cuticle  is  pene- 
trated on  the  head  by  a  number  of  innervations.  These  end  in  minute 
depressions  on  the  surface  of  the  head.  Near  the  mouth  opening  there 
is  one  of  these  depressions  on  the  dorsal  side,  and  apparently  a  sim- 
ilar one  on  the  ventral  side,  while  nearer  the  outer  margin  of  the  head 
there  are  two  ventrally  submedian  and  two  dorsally  submedian  similar 
depressions.  Pores  occur  also  here  and  there  on  the  body  as  well  as 
on  the  neck.  There  are  no  eye-spots.  The  lateral  organs  present  the 


84  NORTH    AMERICAN 

following  appearance  when  seen  from  the  side :  They  appear  to  project 
from  the  surface  of  the  body  very  slightly,  beginning  as  a  tube  having 
a  length  about  one-third  as  great  as  the  corresponding  diameter  of  the 
head.  This  tube  has  very  thin  walls,  and  a  short  distance  in,  appar- 
ently near  the  surface  of  the  body,  a  second  element  appears  in  the 
form  of  a  circle  inside  that  representing  the  contour  of  the  outer  tube. 
This  appears  to  constitute  a  sort  of  core  in  the  midst  of  which  are  a 
number  of  refractive  elements,  resembling  nerve  fibers,  which  pass  in- 
ward and  backward  toward  the  lumen  of  the  oesophagus.  Some  of 
these  elements  are  longer  than  others.  The  focus  passing  inward  picks 
up  one,  then  two,  then  several  more,  so  that  by  the  time  a  view  is  ob- 
tained that  is  wholly  inside  the  body  there  are  seen  a  half  dozen  or 
more  of  these  elements.  It  is  impossible  in  this  view  to  pick  up  an  in- 
ternal connection  of  these  refractive  elements.  The  oesophagus  begins 
just  below  the  transparent  cuticle  as  a  very  narrow  tube,  probably  not 
more  than  one-eighth  as  wide  as  the  corresponding  portion  of  the  neck. 
It  continues  to  have  this  diameter  until  after  it  passes  through  the  nerve- 
ring.  At  a  distance  from  the  nerve-ring  equal  to  about  one  body  diam- 
eter, the  oesophagus  begins  to  change  gradually  into  intestine.  The 
intestine  gradually  widens  out,  so  that  at  a  point  as  far  behind  the  nerve- 
ring  as  the  neck  is  wide  it  has  a  width  one-third  as  great  as  that  of  the 
body.  It  goes  on  increasing  in  this  way  until  at  a  distance  from  the 
nerve  ring  three  times  as  great  it  is  two-fifths  as  wide  as  the  body. 
Near  its  middle  the  intestine  is  half  as  wide  as  the  body. 
The  cells  of  the  intestine  contain  granules  of  variable  size,  the  largest 
having  a  diameter  fully  twice  as  great  as  the  thickness  of  the  cuticle, 
and  the  smallest  being  very  minute.  The  female  has  not  been  seen. 
The  tail  of  the  male  is  slightly  arcuate,  and  is  conoid  to  the  blunt, 
rounded  terminus,  which  has  a  diameter  half  as  great  as  that  of  the 
base  of  the  tail.  There  is  no  spinneret,  and  there  are  no  caudal  glands. 
The  lateral  fields  are  about  one-third  as  wide  as  the  body.  The  nerve- 
ring  surrounds  the  oesophagus  somewhat  obliquely.  Nothing  is  known 
concerning  the  ventral  glands  or  the  excretory  pore.  The  tail  of  the 
male  bears  several  series  of  innervated  papillae.  These  are  sufficiently 
elevated  at  the  surface  of  the  cuticle  to  slightly  break  the  contour  when 
the  tail  is  seen  in  exact  profile.  Where  each  nerve  passes  through  the 
cuticle  there  is  a  very  low,  almost  imperceptible  elevation  at  the  sur- 
face. These  papillae  are  arranged  on  the  ventral  submedian  lines  as 
well  as  on  the  ventral  line.  The  ventral  papillae  just  in  front  of  and 
just  behind  the  anus  are  double.  As  to  particulars  of  the  submedian 
group,  there  are  four  on  the  tail,  one  member  opposite  the  anus;  one 
a  little  farther  back,  a  third  near  the  middle  of  the  tail,  and  a  fourth 
considerably  farther  back.  In  front  of  the  anus  on  each  side  are  eight 
submedian  papillae.  These  occupy  a  distance  more  than  twice  as  great  as 
the  length  of  the  tail,  and  the  distance  between  successive  papillae  in- 


FREE-LIVING   FRESH-WATER   NEMATODES  85 

creases  with  the  distance  from  the  anus,  so  that  the  space  between 
the  seventh  and  eighth  is  about  two-thirds  as  great  as  the  diameter 
of  the  body.  Of  the  median  papillae  on  the  tail  there  are  three;  two 
near  the  anus,  and  one  just  in  front  of  the  middle  of  the  tail,  with  pos- 
sibly a  fourth  farther  back.  In  front  of  the  anus,  of  the  median  papillae 
there  are  two  near  the  anus,  and  ten  additional  ones  about  coextensive 
with  the  submedian  rows  and  distributed  in  the  same  manner,  the  dis- 
tance between  successive  papillae  increasing  with  the  distance  from  the 
anus.  The  two  equal,  arcuate,  uniform,  blunt  spicula  are  about  one  and 
one-third  times  as  long  as  the  anal  body-diameter.  Their  proximal  ends 
are  not  cephalated.  The  ejaculatory  duct  is  about  one-third  as  wide  as 
the  body.  The  vas  deferens  is  about  one-half  as  wide  as  the  body. 
There  are  two  outstretched  testicles,  the  blind  end  of  the  anterior  being 
about  twice  as  far  from  the  end  of  the  neck  as  this  latter  is  from  the 
anterior  extremity.  The  posterior  testicle  is  a  little  shorter  than  the 
anterior. 

Habitat:     Cranberry  bog,  Arlington  Farm. 

ACHROMADORA,  Cobb,  1914. 
Fig.  11,  Plate  V. 

28.     Achromadora  minima,  Cobb. 

For    original    description    see   Macleay    Memorial    Volume,    Sydney, 
1893;  see  also  Journal  Washington  Academy  of  Sciences,  Oct.  4,  1914. 


86  NORTH    AMERICAN 

EXPLANATION  OF  PLATES* 

PLATE  II. 
IOTA,   Cobb,   1913. 

Fig  i.  Iota  octangulare,  n.  sp.  Lateral  view  of  a  female  specimen. 
a,  lip  region;  b,  labial  chitinous  plate  or  expansion;  c,  protruding  muscles  of 
the  spear ;  d,  spear ;  e,  trilobed  base  of  the  spear ;  f,  lumen  of  the  oesophagus ; 
g,  nerve-ring;  h,  beginning  of  the  intestine;  i,  flexure  in  the  single  narrow 
ovary;  j,  excretory  pore;  k,  ventral  row  of  modified  cuticular  elements;  /, 
submedian  row  of  modified  cuticular  elements;  m,  ovum;  n,  muscular  layer; 
o,  anterior  extremity  of  the  uterus ;  p,  uterus ;  q,  cuticle ;  r,  vulva ;  s,  sub- 
median  row  of  modified  cuticular  elements ;  t,  rectum ;  u,  anus ;  v,  terminus. 

RHABDOLAIMUS,  de  Man,   1880. 

Fig.  2.  Rhabdolaimus  minor,  n.  sp.  I,  lateral  view  of  female;  II,  head 
of  the  same,  showing  amphid.  The  head  in  I  is  twisted,  so  that  the  amphid 
appears  as  if  ventral,  or  nearly  so. 

a,  amphid ;  b,  long,  narrow  pharynx ;  c,  anterior  group  of  nerve  cells ;  d, 
nerve-ring ;  e,  cardiac  bulb ;  /,  wall  of  the  intestine ;  g,  flexure  in  anterior 
ovary;  h,  posterior  group  of  nerve  cells;  i,  body  cavity;  j,  lumen  of  intestine; 
k,  ovum;  I,  blind  end  of  posterior  ovary;  m,  egg;  n,  flexure  in  posterior 
ovary ;  o,  cuticle ;  p,  caudal  glands ;  q,  subcuticle ;  r,  vulva ;  s,  rectum ;  t,  anus ; 
u,  nerve  cells  (?)  ;  v,  duct  of  caudal  glands;  w,  spinneret;  x,  lip  region. 

DIPLOGASTER,  Max  Schultz,  1857. 

Fig.  3.  Diplogaster  fictor,  Bastian.  I,  side  view  of  female;  II,  head 
of  the  same  seen  in  dorso-ventral  view,  lips  nearly  closed ;  III,  head 
of  the  same,  lateral  view,  lips  nearly  wide  open;  IV,  head  of  the  same, 
lateral  view,  lips  partially  closed;  V,  front  view  of  mouth,  partially  closed; 
VI,  lateral  view,  posterior  portion  of  a  male  specimen;  VII,  somewhat  dia- 
grammatic perspective  view  showing  markings  of  the  cuticle. 

a,  one  of  the  lips ;  b,  one  of  the  six  cephalic  setae ;  c,  amphid ;  d,  one  of 
the  two  more  or  less  evertible  pharyngeal  hook-shaped  teeth;  e,  median 
oesophageal  bulb ;  /,  nerve-ring ;  g,  anus ;  h,  rectum ;  i,  intestine ;  j,  terminus  ; 
k,  posterior  oesophageal  bulb;  /,  nerve  cells;  m,  renette  cell  (?);  n,  left 
spiculum;  o,  lumen  of  the  intestine;  p',  preanal  male  seta;  p" ,  P' ' ' , 
p' ' ' ' ,  post-anal  male  setae  and  papillae;  q,  one  of  the  cells  of  the  intestine; 
r,  accessory  piece ;  s,  flexure  in  anterior  ovary ;  t,  blind  end  of  anterior  ovary ; 
u,  longitudinal  striae  of  the  cuticle ;  v,  vagina ;  w,  synapsis  in  egg  in  the  an- 
terior uterus,  the  reduced  number  of  chromosomes  being  seven;  x,  one  of  the 
spermatozoa  in  the  ovary;  y,  uterus;  z,  vulva. 

*The  drawings  are  used  by  permission  of  the  Secretary  of  Agriculture,  and  were 
made  by  Mr.  W.  E.  Chambers,  under  the  author's  supervision. 


FREE-LIVING   FRESH-WATER   NEMATODES 
9 


Fig.   2.     Rhabdolaimus  minor,   n.   sp  Fig.    3.      Diplogaster    fictor,    Bastian. 

PLATE  II. 


88  NORTH    AMERICAN 

PLATE  III. 
PRISMATOLAIMUS,  de  Man,  1880. 

Fig.  4.  Prismatolaimus  stenurus,  n.  sp.  I,  lateral  view  of  a  female; 
II,  front  view  of  head ;  III,  side  view  of  head. 

a,  one  of  the  six  cephalic  papillae ;  b,  one  of  the  ten  cephalic  setae ;  c, 
one  of  the  six  thin  lips;  d,  pharynx;  e,  amphid;  f,  lumen  of  the  oesophagus; 
g,  nerve-ring;  h,  cuticle;  i,  nucleus  of  ovum;  /,  vulva;  k,  blind  end  of  pos- 
terior ovary;  /,  egg;  m,  beginning  of  the  intestine;  n,  one  of  the  cells  of  the 
wall  of  the  intestine ;  o,  rectum ;  p,  anus ;  q,  one  of  the  caudal  glands ;  r,  flex- 
ure in  anterior  ovary;  s,  spinneret. 

SPILOPHORA,  Bastian,  1865. 
Fig.  5.    Spilophora  canadensis,  n.  sp.    Side  view  of  male. 

a,  one  of  the  lips ;  b,  dorsal  pharyngeal  tooth  partly  exserted ;  c,  pharynx ; 
d,  base  of  the  pharynx ;  e,  lumen  of  the  oesophagus ;  /,  nerve  cells ;  g,  nerve- 
ring;  h,  excretory  pore;  i,  chitinous  valve  of  the  cardiac  bulb;  /,  one  of  the 
two  lateral,  longitudinal  rows  of  cuticular  markings;  k,  lumen  of  the  intes- 
tine; I,  renette  cell;  m,  nucleus  of  renette  cell;  n,  cell  accessory  to  the  renette 
cell ;  o,  blind  end  of  single  testis ;  p,  point  in  the  cuticle  where  the  striation  is 
reversed ;  q,  vas  deferens ;  r,  one  of  the  spicula ;  s,  anus ;  /,  one  of  the  caudal 
glands;  u,  spinneret. 

MICROLAIMUS,  de  Man,  1880. 

Fig.  6.  Microlaimus  fluviatilis,  n.  sp.  I,  lateral  view  of  female;  II, 
head  of  the  same. 

a,  Mouth  opening;  b,  one  of  the  six  cephalic  papillae;  c,  one  of  the  four 
cephalic  setae;  d,  one  of  the  small  pharyngeal  teeth;  e,  excretory  pore;  /, 
spiral  amphid;  g,  oesophagus;  h,  nerve-ring;  i,  cardiac  bulb;  /,  preliminary 
portion  of  the  intestine ;  k,  renette  cell ;  /,  body  cavity ;  m,  lumen  of  intestine ; 
n,  one  of  the  cells  of  the  intestine;  o,  anus;  p,  flexure  in  posterior  ovary;  q, 
uterus ;  r,  blind  end  of  posterior  ovary ;  s,  one  of  the  three  caudal  glands ;  t, 
spinneret;  uu,  eggs;  v,  vulva;  w,  cuticle. 

TRIPYLA,  Bastian,  1865. 
Fig.  7.     Tripyla  lata,  n.  sp.    Lateral  view,  male  specimen. 

a,  cephalic  seta;  b,  one  of  the  three  lips;  c,  amphid;  d,  spermatozoa;  e. 
spermatocytes  in  anterior  testis ;  /,  posterior  extremity  of  the  oesophagus ;  g, 
nerve-ring;  h,  cuticle;  i,  oesophagus;  /,  lumen  of  oesophagus;  k,  intestine; 
/,  spermatocytes  in  posterior  testis ;  m,  one  of  the  numerous  ventral  male 
papillae ;  n,  vas  deferens ;  o,  retractory  muscle  of  spiculum ;  p,  one  of  the 
spicula ;  q,  lumen  of  the  intestine ;  r,  duct  of  one  of  the  caudal  glands ;  s, 
caudal  gland  ;  t,  spinneret. 


FREE-LIVING  FRESH-WATER    NEMATODES 


Fig.   6.      Microlaimus  fluviatilis,   n.   sp.  Fig.   7.     Tripyla  lata,  n.   sp. 

PLATE  III. 


QO  NORTH    AMERICAN 

PLATE  IV.      ' 
TERATOCEPHALUS,  de  Man,  1876. 

Fig.  8.  Tcratocephalus  cornutus,  n.  sp.  I,  lateral  view  of  a  female;  II, 
lateral  view  of  head,  more  highly  magnified;  III,  front  view  of  head;  IV, 
dorso-ventral  view  showing  lips  wide  open;  V,  cuticle  showing  lateral  field. 

a,  one  of  the  six  movable,  chitinous  lips ;  b,  one  of  the  four  submedian 
cephalic  setae ;  c,  amphid ;  A,  nerve-ring ;  e,  excretory  pore ;  f,  organ  of  un- 
known significance ;  g,  cardiac  bulb ;  h,  intestine ;  i,  anus ;  /,  rectum ;  k,  cu- 
ticle ;  /,  one  of  the  cells  of  the  intestine;  m,  lumen  of  the  intestine;  nn,  flex- 
ures in  ovary ;  o,  egg ;  p,  vulva ;  q,  blind  end  of  posterior  ovary ;  u,  terminus. 

ALAIMUS,  de  Man,  1880. 

Fig.  9.  Alaimus  simplex,  n.  sp.  I,  lateral  view  of  a  female;  II,  an- 
terior extremity,  lateral  view;  III,  posterior  extremity  of  a  male,  lateral  view. 

a,  lip  region ;  b,  pharynx ;  c,  amphid ;  d,  amphid,  enlarged;  e,  group  of 
spermatozoa  at  the  posterior  portion  of  the  ovary;  f,  blind  end  of  ovary; 
g,  male  supplementary  papillae ;  //,  left  spiculum ;  i,  terminus ;  j,  rudimentary 
submedian  elevation  or  flap  of  the  cuticle,  indicating  rudimentary  bursa;  k, 
egg ;  I,  vulva ;  m,  nerve-ring ;  n,  posterior  extremity  of  oesophagus ;  p,  modi- 
fied cells  of  anterior  portion  of  the  intestine ;  q,  cuticle ;  r,  wall  of  the  in- 
testine ;  s,  lumen  of  the  intestine ;  t,  flexure  in  the  single  ovary. 

The  arrangement  of  the  ova  and  eggs  may  need  a  few  words  of  ex- 
planation. The  rounded  blind  end  of  the  reflexed  part  of  the  single  ovary 
is  shown  near  the  group  of  spermatozoa,  e.  The  blind  end  contains  a  large 
number  of  oocytes  of  small  size.  These  oocytes  have  more  than  doubled 
in  size  by  J;he  time  they  have  reached  the  position,  /.  Henceforth  they  be- 
come arranged  single  file,  always  increasing  in  size  until  they  pass  the 
flexure,  t.  "At  k  a  deceptive  appearance  is  shown,  inasmuch  as  the  ripe 
ovum,  k,  has  passed  the  flexure  and  in  its  passage  to  the  uterus  is  pressing 
two  of  the  unripe  ova  apart.  This  accounts  for  the  apparent  anomaly  in 
relative  size  of  the^ova  in  the  vicinity  of  the  flexure. 

PLECTUS,  Bastian,  1865. 
Fig.  10.     Plectus  tubifer,  n.  sp.     Male  specimen,  lateral  view. 

a,  lips ;  b,  papilla-like  cephalic  seta ;  c,  amphid ;  d,  anterior  chamber  of 
pharynx ;  e,  posterior  chamber  of  pharynx ;  /,  lumen  of  the  oesophagus ;  g, 
nerve-ring ;  h,  excretory  pore ;  i,  renette  cell ;  /,  cardiac  bulb ;  k,  vulva  of 
cardiac  bulb ;  /,  cardia ;  m,  lumen  of  intestine ;  n,  blind  end  of  anterior  testis ; 
o,  spermatocyte ;  p,  junction  of  testes;  q,  blind  end  of  posterior  testis;  r,  be- 
ginning of  vas,  deferens;  s,  spermatozoon;  t,  male  glands;  u,  one  of  the  cau- 
dal glands;  v,  anterior  of  the  three  tubular  supplementary  organs;  w,  spicula; 
x,  anus;  y,  one  of  the  nine  male  papillae;  z,  spinneret. 


FREE-LIVING   FRESH-WATER    NEMATODES 


Fig.  8.     Teratocephalus 
cornutus,   n.   sp. 


Fig.  10.     Plectus  tubifer,  n.  sp. 

PLATE  IV. 


92  NORTH    AMERICAN 

PLATE  V. 
ACHROMADORA. 

Fig.  II.  Achromadora  minima,  Cobb.  I,  lateral  view  of  a  female;  II, 
lateral  view  showing  cuticular  markings;  III,  lateral  view  of  head. 

a,  cephalic  papilla;  b,  cephalic  seta;  c,  one  of  the  ribs  of  the  pharynx; 
d,  dorsal  pharyngeal  tooth;  e,  sub-ventral  (?)  pharyngeal  tooth;  f,  pharynx; 
g,  cuticular  markings ;  h,  amphid ;  i,  nerve  cell ;  /,  nerve-ring ;  k,  spinneret ; 
/,  excretory  pore ;  m,  flexure  of  ovary ;  n,  one  of  the  caudal  glands ;  o,  blind 
end  of  posterior  ovary;  p,  anus;  q,  intestine;  r,  vulva;  s,  one  of  the  gran- 
ules of  the  intestine ;  t,  egg. 

DORYLAIMUS,  Dujardin,  1845. 

Fig.  12.  Dorylaimus  fecundus,  n.  sp.  Side  view  of  head  and  tail  of 
female,  and  tail  of  male. 

a,  spear  or  onchus;  b,  one  of  the  six  anterior  cephalic  papillae;  c,  one 
of  the  six  posterior  cephalic  papillae ;  d,  guiding  ring  of  the  spear ;  e,  oeso- 
phagus ;  /,  intestine ;  g,  rectum ;  h,  anus ;  i,  one  of  the  anal  muscles ;  ;',  one  of 
the  four  lateral  caudal,  innervated  papillae ;  k,  cuticle ;  /,  subcuticle ;  m,  mus- 
cular layer;  n,  wall  of  the  intestine;  o,  one  of  the  numerous  oblique  ejacu- 
latory  muscles;  p,  one  of  the  numerous  ventral  male  papillae;  q,  ejaculatory 
duct ;  r,  one  of  the  two  preanal  papillae ;  s,  retractor  muscle  of  one  of  the 
spicula ;  t,  muscular  layer ;  u,  right  spiculum ;  v,  right  accessory  piece. 

IRONUS,    Bastian,    1865. 

Fig.  13.  Ironus  americanus,  n.  sp.  I,  anterior  extremity,  lateral  view, 
oral  organs  everted:  II,  same,  more  highly  magnified;  III,  anterior  extremity 
of  a  specimen  about  to  moult,  showing  two  sets  of  oral  organs,  the  anterior 
set  in  process  of  being  replaced  by  the  posterior;  IV,  posterior  extremity  of 
a  female,  lateral  view. 

a,  one  of  the  three  chitinous  oral  teeth ;  b,  cephalic  papilla ;  c,  cephalic 
seta;  d,  amphid;  e,  pharynx;  /,  anterior  group  of  minute  pharyngeal  teeth; 
g,  posterior  group  of  pharyngeal  teeth ;  h,  oesophagus ;  i,  lining  of  oesopha- 
gus ;  /,  nerve-ring ;  k,  intestine ;  /,  anus ;  m,  base  of  the  tail ;  n,  terminus. 

ONCHOLAIMUS,  Dujardin,  1865. 

Fig.  14.  Oncholaimus  punctatus,  n.  sp.  Lateral  view  of  head  and  tail 
of  male  specimen. 

a,  terminal  flaps  of  lips ;  b,  lip ;  c,  cephalic  papilla ;  d,  one  of  the  papilla- 
like  cephalic  setae;  e,  right  submedian  onchus;  /,  left  submedian  onchus;  g, 
wall  of  pharynx;  h,  intestine;  i,  ejaculatory  duct;  /,  one  of  the  spicula;  k, 
dorsal  onchus ;  I,  amphid ;  m,  duct  of  oesophageal  gland  leading  into  onchus ; 
n,  rectum ;  o,  beginning  of  the  oesophagus ;  p,  anus ;  q,  lining  of  the  oesopha- 
gus; r,  one  of  the  caudal  glands;  s,  one  of  the  two  male  papillae;  t,  ducts  of 
the  caudal  glands;  u,  spinneret. 


FREE-LIVING   FRESH-WATER   NEMATODES 


93 


Fig.    11.     Achromadora   minima,    Cobb 


Fig.    12.      Dorylaitnus  fecundus,  n.   ap. 
A 


Fig.    13.      Ironus  americanus,   n.    sp.  Fig.   14.     Oncholaimus  punctatus,  n.  ip. 

PLATE  V. 


94  NORTH    AMERICAN 

PLATE  VI. 
TRILOBUS,  Bastian,  1865. 

Fig.  15.  Trilobus  longus,  (Leidy),  Bastian.  I,  male  specimen,  lateral 
view;  II  and  III,  head  of  the  same,  lateral  view;  IV,  head,  dorso-ventral 
view;  V,  VI,  and  VII,  enlarged  views  of  the  ventral  supplementary  organs. 

a,  lateral  cephalic  seta ;  b,  cephalic  papilla ;  c,  submedian  cephalic  setae ; 

d,  pharynx;  c,  amphid;  /,  anterior  pharyngeal  tooth;  g,  posterior  pharyngeal 
tooth ;  h,  oesophagus ;  i,  nerve-ring ;  /,  excretory  pore ;  k,  nerve  cells ;  /  gland- 
ular (?)   organs;  m,  lumen  of  intestine;  n,  blind  end  of  anterior  testis ;  o, 
testis;  p,  junction  of  testes;  q,  blind  end  of  posterior  testis;  r,  vas  deferens; 
s,  anterior  male  supplementary  organ  of  the  anterior  series ;  t,  anterior  sup- 
plementary organ  of  the  posterior  series ;  u,  spicula ;  v,  accessory  piece ;  w, 
caudal  gland ;  x,  anus ;  y,  terminus ;  z,  nerve  ending  of  papilla  of  the  supple- 
mentary organ. 

DOLICHODORUS,  nov.  gen. 

»  Fig.  16.  Dolichodorus  heterocephalus,  n.  g.,  n.  sp.  I,  nearly  side  view  of  a 
female;  II,  lateral  view  of  surface  of  head,  more  highly  enlarged;  III,  sagit- 
tal section  of  head;  IV,  dorso-ventral  view  of  head;  V,  front  view  of  head; 
VI,  side  view,  posterior  extremity  of  male ;  VII,  ventral  view  of  posterior 
extremity  of  female;  VIII,  ventral  view  of  posterior  extremity  of  male. 

a,  papilla ;  b,  cephalic  organ  of  unknown  significance ;  c,  spear ;  d,  base  of 
spear;  e,  median  bulb;  /,  nerve-ring;  g,  excretory  pore;  h,  cardiac  swelling; 
t,  intestine ;  /,  anus ;  k,  lateral  caudal  pores ;  I,  terminus ;  m,  blind  end  of  pos- 
terior ovary ;  n,  ovary ;  o,  left  spiculum ;  p,  accessory  piece ;  q,  distal  end  of 
Accessory  piece ;  r,  left  flap  of  bursa ;  s,  terminus  of  male ;  t,  ovum ;  u,  sper- 
matozoa ;  v,  vaginal  muscles ;  w,  uterus ;  x,  vulva ;  y,  anus. 

CYATHOLAIMUS,    Bastian,    1865. 

Fig.  17.  Cyatholaimus  truncatus,  n.  sp.  I,  side  view  of  a  female ;  II,  side 
view  of  head ;  III,  front  view  of  the  same  head ;  IV,  ventral  view  of  anal 
region  of  male;  V,  lateral  view  of  the  same;  VI,  lateral  view  in  the  middle 
of  the  body  showing  cuticular  markings  and  pores. 

a,  submedian  cephalic  seta ;  b,  labial  papillae ;  c,  amphid ;  d,  dorsal  tooth ; 

e,  lateral  cephalic  seta ;  /,  one  of  the  twelve  ribs  of  the  vestibule ;  g,  small 
submedian  pharyngeal  tooth ;  h,  base  of  the  pharynx ;  i,  ejaculatory  duct ;  /, 
intestin* ;  k,  one  of  the  four  male  pre-anal  supplementary  organs ;  I,  one  of 
the  spicula;  m,  anal  muscles;  n,  one  of  the  accessory  pieces;  o,  nerve-ring; 
p,  one  of  the  cells  of  the  intestine ;  q,  lumen  of  the  intestine ;  r,  anus ;  s,  blind 
end  of  reflexed  ovary;   /,  egg;  u,  vulva;  v,  flexure  in  anterior  ovary;  w, 
junction  of  the  ovary  and  uterus;  x,  pores  in  the  cuticle;  3;,  one  of  the  three 
caudal  glands;  z,  male  gland  (?). 


FREE-LIVING   FRESH-WATER   NEMATODES 
i         /c  I 


Fig.    16.      Dolichodorus  heterocephalus,  Fig.   17.     Cyatholaimus  truncatus,  n.  sp. 

n.  g.,  n.  sp.  PLATE  VI. 


96  NORTH    AMERICAN 

PLATE  VII. 

MESOMERMIS. 
Fig.  18.     Mesomermis  virginiana,  n.  sp.     Lateral  view  of  head  and  tail. 

a,  mouth  opening;  b,  one  of  the  anterior  rows  of  cephalic  papillae;  c, 
one  of  the  posterior  row  of  cephalic  papillae ;  d,  pharynx ;  e,  exterior  of  am- 
phid;  /,  interior  of  amphid;  g,  oesophagus;  h,  innervated  papilla;  »,  gland- 
ular cephalic  organs;  /,  nerve-ring;  k,  lumen  of  oesophagus;  /,  intestine;  m, 
ejaculatory  duct ;  n,  body  cavity ;  o,  oblique  copulatory  muscles ;  p,  one  of  the 
submedian  supplementary  organs;  q,  one  of  the  median  supplementary  or- 
gans; r,  spicula;  s,  one  of  the  median  post-anal  supplementary  organs;  t, 
final  submedian  supplementary  organs;  u,  submedian  supplementary  organ. 

ETHMOLAIMUS,  de  Man,  1880. 
Fig.  19.    Ethmolaimus  americanus,  n.  sp.    Lateral  view  of  a  female. 

a,  lips ;  b,  minute  dorsal  and  ventral  pharyngeal  teeth ;  c,  one  of  the 
four  cephalic  setae;  d,  amphid;  e,  pharynx;  /,  nerve-ring;  g,  excretory  pore; 
h,  nerve  cells;  \,  cardiac  bulb;  j,  beginning  of  the  intestine;  k,  renette 
cell  (?);  /,  beginning  of  main  portion  of  the  intestine;  m,  one  of  two 
pairs  of  unicellular  organs  of  unknown  significance;  n,  cuticle;  o,  one  of  the 
cells  of  the  intestine;  p,  subcuticle;  q  and  r,  body  cavity;  s,  vulva;  t,  nuclei 
of  one  of  the  muscle  cells ;  u,  spinneret ;  v,  one  of  the  caudal  glands ;  w,  anus. 

MONHYSTERA,  Bastian,  1865. 

Fig.  20.  Monhystera  sentiens,  n.  sp.  I,  side  view  of  a  female;  II,  side 
view  of  head  of  the  same;  III,  side  view  of  posterior  extremity  of  a  male. 

a,  pharynx ;  b,  submedian  cephalic  seta ;  c,  lateral  cephalic  seta ;  d,  sper- 
matozoon ;  e,  amphid ;  /,  lining  of  oesophagus ;  g,  oesophagus ;  h,  subcephalic 
setae;  i,  lumen  of  intestine;  /,  nerve  cells;  k,  nerve-ring;  /,  striated  lip  re- 
gion; m,  left  spiculum;  n,  glandular  structure  associated  with  amphid;  o, 
blind  end  of  single  ovary;  pp,  the  three  caudal  glands;  q,  anal  muscles;  r, 
spinneret:  s,  beginning  of  intestine;  t,  anus;  u,  one  of  the  cells  composing 
the  intestine;  v,  vulva;  w,  egg,  the  spermatozoa  "d"  being  outside  of  the  egg 
''«'";  x,  egg  in  synapsis ;  y,  vaginal  glands ;  z,  ovum. 

ONCHOLAIMELLUS,  de  Man,  1886. 

Fig.  21.  Oncholaimellus  heterurus,  n.  sp.  I,  side  view  of  head ;  II,  ven- 
tral view  of  head;  III,  side  view  of  tail  end  of  male;  IV,  ventral  view  of 
anal  region  of  male. 

a,  excretory  pore;  b,  submedian  cephalic  seta;  c,  pharynx;  d,  left  flap 
of  bursa;  e,  oesophagus;  /,  left  spiculum;  g,  accessory  piece;  h,  amphid;  », 
male  post-anal  seta  and  papilla;  j,  lateral  seta;  k,  spinneret;  I,  thin  lips. 


FREE-LIVING    FRESH-WATER    NEMATODES 

a 

b 


Fig.   18.      Mesomermis  virgimana,  n.  sp 


Fig.  20.     Monhys'tera  sentiens,  n.  sp.  Fig.  21.     Oncholaimellus  he       ,n», 

PLATE  VI I.  n"  sp" 


98  NORTH    AMERICAN 

PLATE  VIII. 

CEPHALOBUS,   Bastian,   1865. 
Fig.  22.     Cephalobus  sub-elongatus,  n.  sp.     Lateral  view  of  a  female. 

a,  lips ;  b,  pharynx ;  c,  anterior  portion  of  oesophagus ;  d,  posterior  ex- 
tremity of  anterior  portion  of  oesophagus;  e,  nerve-ring;  /,  cardiac  bulb;  g, 
beginning  of  intestine ;  h,  one  of  the  cells  of  the  intestine ;  i,  lumen  of  the 
intestine ;  /,  excretory  pore ;  k,  cardiac  valve ;  I,  renette  cell ;  m,  flexure  in 
single  ovary;  n,  cuticle;  o,  ovary;  p,  spermatozoon  in  uterus;  q,  vulva;  r, 
nucleus  in  ovum;  s,  body  cavity;  t,  anus;  u,  ripe  ovum;  v,  unripe  ovum;  w, 
oocyte;  x,  blind  end  of  ovary;  y,  rectum;  z,  terminus. 

5k- • 

BASTIANA,  de  Man,  1876.  %'  , 

Fig.  23.    Bastiana  exilis,  n.  sp.    Lateral  view  of  a  male  specimen. 

a,  one  of  the  six  cephalic  papillae;  b,  one  of  the  posterior  set  of  four 
submedian  cephalic  setae ;  c,  one  of  the  anterior  set  of  six  cephalic  setae ;  d, 
oesophagus ;  e,  cervical  seta ;  /,  amphid ;  g,  one  of  the  cells  of  the  intestine ; 
h,  one  of  the  numerous  male  supplementary  organs ;  i,  blind  end  of  the  two 
testes;  j,  nerve-ring;  k,  posterior  extremity  of  oesophagus,  (pseudo-bulb); 
/,  left  spiculum;  m,  cuticle;  n,  spermatozoon;  o,  anal  muscle;  p,  treminus;  q, 
vas  def erens ;  r,  intestine. 

MESOMERMIS,   Dady. 

Figure  24.  Mesomermis  Virginia  n.  sp.  Neck  and  head  of  the  same 
species  shown  in  figure  18,  showing  how  the  deteriorated  oesophagus  changes 
rather  gradually  into  the  intestine. 

a,  mouth-opening ;  b,  one  of  the  anterior  row  of  cephalic  papillae ;  c,  one 
of  the  posterior  row  of  cephalic  papillae;  d,  pharynx;  e,  exterior  of  amphid; 
/,  interior  of  amphid;  g,  oesophagus;  h,  innervated  papilla;  i,  glandular 
cephalic  organs;  j,  nervering;  k,  lumen  of  oesophagus;  /,  intestine. 

APHANOLAIMUS,  de  Man,  1880. 

Fig.  25.  Aphanolaimus  spiriferus,  n.  sp.  I,  lateral  view,  anterior  ex- 
tremity of  a  female;  II,  lateral  view,  posterior  extremity  of  a  female;  III, 
lateral  view  of  head,  more  highly  magnified;  IV,  one  of  the  male  supple- 
mentary organs ;  V,  lateral  view  of  posterior  extremity  of  male. 

a,  mouth  opening ;  b,  amphid ;  c,  lumen  of  oesophagus ;  d,  pigmented  eye- 
spot  (?);  e,  intestine;  /,  nerve-cell;  g,  rectum;  h,  nerve-ring;  i,  anus;  k, 
oesophagus ;  /,  caudal  gland ;  m,  duct  of  one  of  the  caudal  glands ;  n,  gland- 
ular body  at  base  of  neck;  o,  spinneret;  p,  ejaculatory  duct;  q,  intestine;  r, 
anterior  end  of  cloaca ;  s,  right  spiculum ;  t,  backward  pointing  accessory 
piece;  u,  nerve-cells  (?)  ;  v,  one  of  the  numerous  male  supplementary  organs. 


FREE-LIVING   FRESH-WATER    NEMATODES 


99 


Fig.  22. 

Cephalobus 

subelongatus, 

n.  sp. 


Fig.  24. 


</    X  *%          ^ 

'MeTo'raermis  virginiana,  n.  sp.          Fig.   25.     Alphanolaimus  spiriferus,  n.   sp. 

PLATE  VIII. 


THE 

ASYMMETRY  OF  THE  NEMATODE 
Bunonema  iiiequale,  n.sp. 

BY  N.  A.  COBB 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY,  III 

The  genus  Bunonema  was  established  in  1905  by  Dr.  L.  A.  Jagers- 
kiold  for  the  reception  of  species  from  Kerguelen  Island  and  from 
the  Schwarzwald.1  Recently  species  belonging  to  this  genus  have 
been  found  in  Switzerland  and  examined  by  Dr.  G.  Steiner.2 

The  present  account  deals  with  species  found  at  Washington, 
D.  C.,  U.  S.  A.,  in  the  rotting  wood  of  red  oak.  The  specimens  have 
been  examined  with  considerable  care  on  account  of  their  remarkable 
asymmetry.  It  seems  probable  that  this  asymmetry  is  characteristic 
of  the  genus.  The  following  is  an  extended  description  of  the  generic 
characters  of  Bunonema. 

BUNONEMA  Jagerskiold  1905 

The  rather  thin  layers  of  the  transparent  naked  cuticle  are  tra- 
versed by  four  hundred  to  five  hundred  transverse  striae,  rather  diffi- 
cult of  resolution.  In  at  least  a  part  of  the  circumference  the  annules 
are  resolvable  into  dot-like  elements,  which  apparently  are  the  ends 
of  minute,  radial,  rod-like  elements  in  the  cuticle.  These  elements 
are  so  arranged,  at  least  on  the  right  side  of  the  body,  as  to  give  rise 
to  a  tessellation,  in  the  midst  of  which,  on  the  lateral  field,  there  is 
usually  a  longitudinal  series  of  tubercles  of  relatively  large  size,  ar- 
ranged in  one  or  two  rows,  extending  from  near  the  head  to  near 
the  terminus.  When  two  rows  of  tubercles  are  present,  one  or  more 
pairs  at  each  end  of  the  series  are  likely  to  be  combined  into  a  single 
tubercle.  When  viewed  en  face  the  surface  of  these  tubercles  pre- 
sents a  punctate  appearance,  and  their  circumferences  not  infre- 
quently show  the  presence  of  minute  papilla-like  elements,  which  do 
not  break  the  contour,  but  which  appear  to  have  passing  to  them, 
from  the  body  wall,  linear  elements, — suggesting  that  the  tubercles 
are  innervated.  When  seen  in  profile  the  tubercles  appear  to  be  made 

1  "Bunonema  richtersi,  n.  g.,  n.  sp.,"  Zoologischer  Anzeiger,  28  February,  1905. 

2  "Freilebende  Nematoden  aus  der  Schweiz,"  Archiv  fur  Hydrobiologie  und 
Planktonkunde,  1913-14. 

.  101 


102  ASYMMETRY   OF   THE   NEMATODE 

of  rods,  or  possibly  laminae,  corresponding  in  number  with  the  annules 
of  the  adjacent  cuticle.  The  dot-like  elements  of  the  cuticle  lose  their 
linear  arrangement  near  the  anterior  extremity, — where  the  somatic 
cuticle  joins  the  much  thinner  and  more  flexible  cuticle  of  the  head. 
This  junction  is  of  such  a  nature  that  the  lip  region  can  be  partially 
withdrawn  into  the  body  cavity  somewhat  as  into  a  shell.  In  other 
words,  where  the  somatic  cuticle  ceases,  there  is  a  rather  distinct 
shoulder  and  a  rather  rapid  diminution  in  diameter  to  the  base  of  the 
lip  region.  The  expanded  lip  region  is  thus  set  off  by  a  very  distinct 
constriction.  Apart  from  the  transverse  and  punctate  markings, 
the  cuticle  is  traversed  by  five  distinct  longitudinal  wings,  one  lateral, 
one  ventral,  one  dorsal,  and  two  left  submedian.  The  existence  of 
each  of  these  wings  is  indicated  by  the  presence  of  their  twTo  crenate  re- 
fractive margins,  close  together.  These  lines  extend  from  near  the 
head  to  the  anus,  or  beyond. 

The  posterior  portion  of  the  neck  is  more  or  less  cylindroid,  but 
it  becomes  convex-conoid  toward  the  truncated  head,  which  bears  in 
the  midst  of  the  expanded  lip  region  a  somewhat  depressed  mouth 
opening,  surrounded  by  obscure,  more  or  less  amalgamated  lips.  There 
are  six  inconspicuous,  minute,  innervated,  more  or  less  forward-point- 
ing papillae,  arranged  in  a  rather  asymmetrical  fashion  on  the  margin 
of  the  head.  There  are  six  spreading,  more  or  less  curved,  tapering 
cephalic  setae,  arranged  in  an  asymmetrical  manner,  the  two  largest 
being  apparently  dextral,  but  possibly  median,  the  two  next  smaller 
left  submedian,  and  the  two  smallest,  which  are  in  fact  papilla-like, 
right  submedian.  The  longest  of  these  setae  are  usually  nearly  as 
long  as  the  head  is  wide  opposite  the  base  of  the  pharynx.  The  setae 
often  present  the  peculiarity  of  being  saccate  at  the  base,  more  espe- 
cially the  largest  ones.  The  more  or  less  triquetrous,  regular,  narrow 
pharynx  is  entered  through  a  narrow  vestibule,  and  has  its  walls  rather 
distinctly  chitinized,  so  that  it  is  a  very  distinct  feature  of  the  head. 
There  is  no  pharyngeal  armature.  No  amphids  have  been  seen,  and 
there  are  no  eye-spots.  The  rhabditoid  oesophagus  has  an  ellipsoidal 
median  bulb,  two-thirds  as  wide  as  the  middle  of  the  neck,  and  a  pro- 
late to  pyriform  cardiac  bulb,  two-thirds  as  wide  as  the  base  of  the 
neck.  The  lining  of  the  oesophagus  is  a  distinct  feature  throughout 
its  length,  more  particularly  in  its  anterior  half,  where  it  is  indi- 
cated by  refractive  elements  occupying  a  considerable  portion  of 
the  diameter.  Both  bulbs  contain  valves,  that  of  the  median  bulb 
being  simple  and  elongated,  that  of  the  cardiac  bulb  more  complicated. 


BTJNONEMA    INEQUALE  103 

and  three-parted,  but  destitute  of  striations.  The  more  or  less  thin- 
walled  intestine,  which  is  separated  from  the  oesophagus  by  a  very 
distinct  constriction,  becomes  at  once  about  two-fifths  as  wide  as 
the  body,  and  is  made  up  of  cells  of  such  a  size  that  about  two  are 
required  to  complete  its  circumference.  The  lumen  is  often  a  dis- 
tinct feature,  on  account  of  the  refractive  nature  of  the  lining  of  the 
intestine,  and  its  zig-zag  course  indicates  clearly  the  small  number 
of  cells  composing  the  circumference  of  the  intestine.  The  intes- 
tine often  expands  a  short  distance  behind  the  cardiac  collum,  so 
as  to  be  two-thirds  as  wide  as  the  bulb.  The  cells  of  the  intestine 
contain  colorless,  more  or  less  scattered  granules  of  variable  size, 
the  largest  of  which  have  a  diameter  nearly  equal  to  that  of  the  pharynx, 
the  smallest  of  which  are  very  much  smaller.  There  is  an  indis- 
tinct flattish  cardia.  There  is  no  pre-rectum.  The  rectum  is  nar- 
row and  rather  long  and  slender,  usually  about  one  and  one-half  times 
as  long  as  the  anal  body  diameter.  The  anus  of  the  female  is  usually 
rather  conspicuous,  on  account  of  the  development  of  the  anterior  lip, 
which  in  adults  constitutes  a  flap  extending  backward  over  the  anus 
and  outward  from  the  surface  of  the  body  at  a  slight  angle.  This  anal 
flap  is  less  pronounced  in  the  young,  and  is  almost  altogether  absent 
in  very  young  larvae.  The  tail  begins  to  taper  from  some  distance 
in  front  of  the  anus,  and  is  first  convex-conoid  and  finally  concave- 
conoid,  to  the  exceedingly  acute,  simple,  unarmed,  symmetrical  ter- 
minus. There  is  no  spinneret,  and  there  are  no  caudal  glands,  nor 
have  any  definite  lateral  papillae,  such  as  those  of  the  female  of  Rhab- 
ditis,  been  seen.  The  renette  cell  is  probably  located  in  the  vicinity 
of  the  cardia.  The  excretory  pore  occurs  opposite  the  anterior  por- 
tion of  the  cardiac  bulb,  and  usually  empties  on  the  right  side  of  the 
ventral  wing.  The  rather  inconspicuous  nerve  ring  surrounds  the 
oesophagus  somewhat  obliquely.  From  the  fairly  well-developed 
vulva  the  vagina  leads  inward  at  right  angles  to  the  ventral  surface 
about  two-fifths  the  distance  across  the  body,  where  it  joins  the  two 
symmetrically  placed  uteri,  each  of  which  is  fully  as  long  as  the  body 
is  wide.  The  reflexed  ovaries  extend  back  toward  the  vulva.  The 
eggs  are  of  such  a  size  that  each  uterus  probably  will  hold  only  one 
at  a  time.  They  appear  usually  to  be  about  as  long  as  the  body  is 
wide,  and  about  two-thirds  as  wide  as  long.  The  tail  of  the  male  has 
the  same  general  form  as  that  of  the  female,  but  is  characterized  by 
the  development  of  the  cuticle  into  a  very  rudimentary  bursa.  The 
two  equal,  simple,  frail,  sub-arcuate,  relatively  long  and  slender,  acute 


104  ASYMMETRY  OF  THE  NEMATODE 

spicula  are  usually  about  two  and  one-half  times  as  long  as  the  anal 
body  diameter,  and  are  accompanied  by  an  accessory  piece  about 
half  as  long,  and  arranged  parallel  to  them.  The  spicula  are  more 
or  less  cephalated  by  expansion.  The  accessory  piece  is  usually  quite 
as  conspicuous  a  feature  as  the  spicula,  since  it  is  often  slightly  colored, 
while  the  spicula  are  colorless.  The  male  papillae  are  reminiscent  of 
those  of  Cephalobus.  In  the  only  males  examined  there  appear  to  be 
eight  somewhat  asymmetrically  placed  pairs,  one  pair  opposite  the 
anus,  two  pre-anal,  and  five  post-anal.  These  papillae  are  flattish, 
innervated,  minute,  and  inconspicuous. 

The  young  larvae  of  Bunonema  do  not  bear  tubercles.  On  the 
species  that  bear  them  the  tubercles  become  permanent  elevations  dur- 
ing the  last  two  moults.  Just  previous  to  the  final  moult  they  ap- 
pear to  be  smaller  and  simpler  than  when  fully  developed.  There  is 
little  if  any  evidence  on  the  right  side  of  very  young  larvae  of  the  very 
remarkable  transformation  which  is  to  take  place  in  the  course  of  growth ; 
the  cuticle  differs  from  that  of  the  left  side  so  little  that  it  is  only  by 
careful  scrutiny  that  the  differences  can  be  detected.  There  are  no 
reticulations  and  there  is  very  little  evidence  of  punctation.  Previous 
to  the  two  last  moults  the  cuticle  of  the  right  side  is  differentiated  from 
that  of  the  left  to  a  greater  or  less  extent.  Probably  at  the  first  moult, 
the  dexter  cuticle  becomes  slightly  thicker  and  almost  imperceptibly 
colored.  The  anal  flap  does  not  exist,  or  at  least  is  in  no  wise  promi- 
nent, on  young  larvae.  The  cephalic  setae  and  other  cephalic  organs 
are  neither  so  strongly  developed,  nor  so  complicated,  on  the  larvae  as 
on  the  adults. 

When  a  specimen  of  Bunonema  is  mounted  in  water,  with  just  suffi- 
cient space  between  the  coverglass  and  the  slide  for  the  nematode  to 
move  about  freely  and  without  friction,  it  is  seen  to  have  the  charac- 
teristic movement  of  nematodes,  that  is  to  say,  the  normal  flexures 
of  the  body  are  in  the  dorso-ventral  plane.  This  brings  the  tubercles 
either  squarely  toward  the  observer,  or  squarely  on  the  far  side  of 
the  body.  At  the  same  time  the  excretory  pore,  the  anus  and  the  vulva 
come  into  exact  profile. 

In  manipulating  specimens  on  the  microscope  slides  it  sometimes 
happens  that  a  tubercle  is  torn  loose,  and  in  such  cases  the  tubercle 
often  comes  off  entire,  as  if  there  existed  a  definite  junction  along  its 
periphery,  or  at  least  as  if  the  peripheral  attachment  were  weak. 
Such  losses  may  in  part  account  for  the  occasional  irregular  arrange- 
ment of  the  tubercles.  Specimens  are  not  infrequently  seen  in  which 


BUNONEMA    INEQUALE  105 

one  member  of  a  pair  of  tubercles  is  missing,  or  where  one  member 
of  a  moniliform  series  appears  to  be  missing,  and  the  natural  inference 
is  that  such  tubercles  never  existed.  This  inference  may,  however, 
be  incorrect,  as  there  is  very  little  evidence  left  to  tell  of  the  acci- 
dental removal  of  a  tubercle;  no  very  definite  scar  remains  to  tell 
the  tale. 

Bunonema  can  exert  suction  so  as  to  attach  itself  by  the  aid  of  its 
lips  even  to  smooth  surfaces  like  glass.  Specimens  sometimes  may 
be  seen  to  attach  themselves  firmly  by  the  head,  and  to  wave  back 
and  forth  through  the  water  in  which  they  are  mounted. 

It  is  clear  that  Bunonema  is  cloeely  related  to  Rhabditis.  This 
is  shown  by  the  structure  of  the  pharynx,  oesophagus,  intestine,  ex- 
cretory system,  and  sexual  organs.  With  reference  to  these  latter, 
there  is  the  difference  that  in  Bunonema  the  bursa  is  rudimentary 
and  the  male  papillae  reduced  in  size  so  as  to  resemble  those  of 
Cephalobus.  Bunonema  appears  therefore  to  be  related  to  Cephalobus, 
especially  that  group  of  Cephalobi  in  which  the  labial  structures  are 
somewhat  elaborate. 

The  most  obvious  source  of  food  for  the  species  of  Bunonema  here 
described  is  the  mycelium  of  wood-infesting  fungi,  which  is  abundant 
in  the  cells  of  the  rotting  wood  inhabited  by  the  Bunonema.  It  may 
be  that  the  peculiar  modifications  of  the  cuticle  are  triturating  organs 
enabling  the  nematodes  to  break  down  the  walls  of  fungus  mycelium 
and  so  obtain  the  contents  of  the  mycelial  cells  with  greater  ease. 
No  organized  food  has  been  seen  in  the  intestine  of  Bunonema,  but 
occasionally  granules  have  been  seen  that  resembled  those  of  the  cell 
contents  of  the  fungi. 

DESCRIPTIONS  OF  THE  SPECIES 

4.2    16.      23.      '57. '29.    94. 

1.  Bunonema  inequale,  n.  sp.  3^7  5^2  iu)  7~i  27e  '  '  The  cuticle  of 
about  three-fourths  of  the  right  side  of  the  body  presents  a  rudely  hexagonal 
network  or  tessellation.  The  meshes  of  this  network  are  of  variable  size,  those 
nearest  the  dorsal  and  ventral  lines  being  the  smaller.  The  division  lines  of 
the  tessellation  of  the  cuticle  are  due  to  the  peculiar  arrangement  of  the  minute 
strongly  refractive  cuticular  elements  into  which  portions  of  the  transverse  striae 
are  resolvable.  The  tessellation  becomes  much  finer  toward  the  extremities  of 
the  body,  where  the  dot-like  refractive  elements  are  no  longer  arranged  regularly. 
Thence  onward  toward  the  extremities  the  cuticle  is  not  striated  and  is  more 
nearly  colorless,  and  very  transparent. 

Opposite  the  right  lateral  line  there  is  a  very  prominent  single  series  of  slightly 
yellowish,  relatively  large,  projecting,  cushion-shaped,  striated,  chitinous  ap- 


106  ASYMMETRY    OF   THE    NEMATODE 

pendages  or  tubercles,  which  through  the  middle  of  the  body  are  about  half  as 
high  as  they  are  wide.  The  tubercles  are  of  rounded  or  ellipsoidal  form,  and 
when  seen  en  face  sometimes  show  on  their  punctate  surface  the  presence  of  three, 
four,  five,  or  more  exceedingly  minute  papilla-like  elements  encircling  the  axis  of 
the  appendage,  this  axis  of  course  being  radial  and  perpendicular  to  the  surface 
of  the  body.  In  the  specimen  from  which  the  description  was  derived,  which 
appeared  to  be  an  average  female  about  to  undergo  the  final  moult,  there  were 
sixteen  of  these  appendages,  forming  a  dextral  row  extending  from  the  lips  to 
near  the  anus.  Those  near  the  ends  of  the  series  were  smaller  than  those  near 
the  middle,  that  on  the  lips  being  the  smallest  of  all.  Throughout  the  middle 
portion  of  the  body  the  tubercles  are  of  rather  uniform  size.  Anteriorly  they  be- 
gin to  diminish  in  size  near  the  base  of  the  neck,  so  that  the  bluntly  conoid  tu- 
bercle opposite  the  base  of  the  pharynx  has  a  diameter  only  one-third  as  great  as 
that  of  the  one  near  the  middle  of  the  body.  The  posterior  tubercle,  near  the 
anus,  is  of  about  the  same  size  as  that  opposite  the  base  of  the  pharynx.  When 
seen  in  profile,  that  is,  when  the  nematode  is  viewed  dorso-ventrally,  the  tubercles 
exhibit  somewhat  the  same  degree  of  striation  as  the  adjacent  cuticle,  but  the 
striae,  or  elements  thereof,  appear  as  if  arranged  in  a  somewhat  fan-shaped  man- 
ner. When  the  body  is  arcuate  and  twisted,  so  that  the  row  of  appendages  is  on 
the  outside  of  the  curve,  the  distance  between  the  appendages  at  the  middle  of 
the  body  nearly  equals  the  diameter  of  one  of  the  appendages.  When  the  body 
is  curved  in  the  other  direction,  the  tubercles  may  be  nearly  in  contact.  The  ex- 
terior of  the  tubercular  appendages  is  distinctly  striated,  and  sometimes  tessel- 
lated, the  striae  being  of  about  the  same  size  and  nature  as  those  of  the  rest  of 
the  cuticle. 

The  following  is  a  detailed  description  of  these  interesting  tubercles  as  they 
occurred  on  an  adult  male  specimen  fixed  in  Fleming's  solution,  and  examined 
soon  afterward  in  water.  The  specimen  was  arcuate  and  the  tubercles  were  on 
the  inside  of  the  curve.  The  first  or  labial  tubercle,  standing  halfway  between 
the  two  relatively  large  and  apparently  dextral  submedian  cephalic  setae,  ap- 
peared somewhat  thumb-shaped  in  contour,  and  when  seen  in  optical  section 
seemed  to  have  a  refractive  chitinous  core  of  a  slightly  greenish  color.  This  tu- 
bercle was  arcuate,  and  its  apex  was  turned  outward  so  as  to  be  nearly  at  right 
angles  to  the  body  axis.  The  second  tubercle,  slightly  behind  the  base  of  the 
pharynx,  was  bluntly  conoid,  the  longitudinal  optical  section  being  approxi- 
mately equilateral.  The  cap  or  outer  half  of  the  cone  was  a  grayish  green  refrac- 
tive chitinous  element,  whose  structure  showed  comparatively  little  detail.  The 
contour  of  this  cap  when  seen  in  optical  longitudinal  section  indicated  the  pres- 
ence of  a  slight  constriction  half  way  between  its  apex  and  its  base.  Inside  the 
cap  the  tubercle  appeared  as  if  radially  striated,  the  number  of  striae  being  about 
ten.  As  these  striae  appeared  to  be  more  or  less  visible  in  every  longitudinal  op- 
tical section,it  would  seem  as  if  they  must  be  the  optical  expression  of  a  columnar 
or  laminated  structure.  When  the  tubercles  were  viewed  in  longitudinal  optical 
section,  the  intermediate  somatic  cuticle,  that  is  the  cuticle  between  successive 
tubercles,  presented  refractive  features  related  to  the  tessellation  so  strikingly 
displayed  when  the  animal  is  viewed  from  the  right  side.  The  plainer  or  less 
complicated  portions  of  the  cuticle,  as  thus  seen  in  longitudinal  section,  repre- 
sent the  "lacunae"  of  the  tessellation,  while  the  refractive  places  represent  the 


BUNONEMA    INEQUALE 


107 


Fig.  1.  Bunonema  inequale, 
n.  sp.  I,  ventral  view  of  male; 
//,  ventral  view  of  the  head  of 
larva;  ///,  IV,  V,  ventral,  front 
and  lateral  views  of  the  head  of 
adult  specimens;  the  three  fig- 
ures are  derived  from  three  dif- 
ferent specimens;  VI,  lateral 
view  of  tail  end  of  the  male; 

VII,  cross-section  taken  near  the 
middle  of  the  body   and  pass- 
ing through  one  of  the  tubercles; 

VIII,  ventral  surface  view  of  a 
segment  of  the  body,  showing 
details  of  the  tessellation,  rod- 
like    structures,    tubercle    and 
subtubercles. 

Nearly  all  the  figures  illus- 
trate the  remarkableasymmetry 
of  Bunonema,  but  this  feature  is 
most  noticeable  in  figures  I,  III, 
IV  and  VII. 

a,  forward  projecting  mem- 
brane half  encircling  the 
mouth-opening  on  the  right  side 
of  the  front  of  the  head;  fc,  dcx- 
tral  sub-median  (?)  cephalic 
seta;  c,  labial  tubercle;  d,  one 
of  the  two  left-hand  sub-median 
cephalic  setae;  e,  pharynx;  /, 
anterior  border  of  the  dextra! 
cuticular  armament;  g,  mem- 
bers of  the  dextral  series  of  tuber- 
cles; h,  one  of  the  subtubercles; 
t,  repetitive  elements  connected 
with  the  large  median  (?)  cephalic 
setae;  j,  saccate  base  of  one  of 
the  largest  setae;  k,  nerve  ring; 
I,  excretory  pore;  m,  cardiac 
bulb;  n,  border  of  the  dextral 
cuticular  armament;  o,  median 
wing;  p,  reflexed  blind  end  of 
the  single  testis;  q,  spicula;  r, 
anterior  pair  of  male  papillae; 
s,  right  hand  member  of  the 
second  pair  ot  male  papillae;  t, 
accessory  piece;  u,  right  hand 
member  of  the  third  pair  of 
male  papillae;  »,  fourth  pair  of 
male  papillae;  u,  right  hand 
member  of  the  fifth  pair  of  male 
papillae;  x,  sixth  and  seventh 
pairs  of  male  papillae, — dorsaliy 
submedian;  y,  hindermost  pair 
of  male  papillae — subventral; 
z,  terminus,  from  which  the  pos- 
terior end  of  the  cuticular  arma- 
ment is  separated  by  a  furca- 
tion. 


108  ASYMMETRY   OF   THE   NEMATODE 

elements  composing  the  net.  There  were  about  five  of  these  refractive  places 
between  the  second  and  third  tubercles,  four  between  the  third  and  fourth,  two 
between  the  fourth  and  fifth,  and  fifth  and  sixth,  these  numbers  corresponding  to 
the  increasing  coarseness  of  the  tessellation  on  the  posterior  part  of  the  neck. 

The  third  tubercle  had  the  form  of  a  truncated  cone.  It  was  a  little  higher 
than  the  second,  and  the  sides  of  the  cone  .were  somewhat  steeper.  It  had  a  chi- 
tinous  cap  like  that  of  the  second  tubercle  but  truncated,  and  the  outer  surface 
of  this  cap  bore  on  its  margin  exceedingly  minute,  round,  flatish  sub-tubercles 
— perhaps  four  only — so  arranged  that  in  optical  section  the  middle  of  the  face 
of  the  tubercle  appeared  almost  imperceptibly  depressed.  The  chitinous  cap 
was  also  hollowed  on  its  inner  concave  face,  the  depth  of  the  excavation  being 
about  three-fifths  the  entire  depth  of  the  cap.  This  tubercle  was  also  columnar 
in  structure,  the  number  of  elements  appearing  in  the  optical  section  being 
slightly  greater  than  in  number  two, — perhaps  12.  Tubercle  number  four  was 
shaped  very  much  like  number  three,  but  was  a  little  more  rounded  on  its  exterior 
surface,  so  that  the  entire  tubercle  in  optical  section  presented  a  rounded  contour ; 
its  cap  being  about  as  thin  as  that  of  number  three,  but  extending  farther  over 
the  surface  of  the  tubercle,  extending  in  fact,  nearly  to  the  general  body  surface. 
The  internal  structure  was  like  that  in  numbers  two  and  three,  except  that  the 
number  of  elements  was  slightly  greater,  and  the  outer  elements  were  spread 
apart  as  they  extended  outward,  so  that  the  striation  appeared  somewhat  fan- 
shaped.  This  fourth  tubercle  stood  half  way  between  the  median  and  cardiac 
bulbs,  and  its  surface  bore  the  same  kind  of  minute  subsidiary  surface  tubercles 
as  were  noted  on  the  third.  The  number  of  these  subsidiary  tubercles  was  slightly 
greater  on  the  fourth  than  on  the  third;  there  appeared  to  be  at  least  five  or  six 
of  them.  The  fifth  tubercle  was  very  much  like  the  fourth,  but  slightly  smaller, 
and  also  bore  the  minute  subsidiary  surface  tubercles  mentioned  in  connection 
with  the  third  and  fourth,  but  fewer  of  them,  in  fact  there  was  perhaps  only  one. 
The  sixth  tubercle  was  somewhat  asymmetrical  in  optical  section,  wider  than 
any  of  the  preceding,  and  composed  of  a  greater  number  of  elements.  Its  chi- 
tinous cap  was  slightly  thinner  than  that  of  number  five,  just  as  that  of  number 
five  was  slightly  thinner  than  that  of  number  four.  This  tubercle  was  located 
opposite  the  anterior  portion  of  the  intestine.  It  remained  uncertain  whether 
this  sixth  tubercle  bore  any  of  the  minute  subsidiary  surface  tubercles.  The 
columnar  structure  of  the  third,  fourth  and  fifth  tubercles,  especially  the  two 
former,  did  not  appear  to  be  absolutely  uniform,  and  it  seemed  likely  that  this 
lack  of  uniformity  was  due  to  the  optical  effect  of  special  elements  passing  radi- 
ally through  the  tubercle  to  the  minute  subtuberclcs,  and  suggested  the  possi- 
bility of  the  presence  in  the  tubercles  of  nerve  elements  connected  with  the  small 
subsidiary  tubercles.  From  the  sixth  onward  the  tubercles  were  of  varying  size, 
sometimes  a  little  smaller  than  number  five,  sometimes  as  large  as  number  six, 
the  six  or  seven  along  the  middle  portion  of  the  body  tending  to  be  smaller,  and 
two  or  three  in  the  proximity  of  the  spicula  tending  to  be  larger.  The  chitinous 
caps  were  less  pronounced  through  the  middle  of  the  body  and,  on  account  of 
their  retractive  properties,  appeared  merely  as  an  accentuated  contour;  that  is 
to  say,  when  seen  in  exact  optical  longitudinal  section  the  chitinous  covering 
gave  rise  to  a  sharp  dark  contour,  which  contrasted  strongly  with  the  contour  pro- 
duced by  the  corresponding  portion  of  the  somatic  cuticle  between  the  tubercles. 


BUNONEMA    INEQUALE  109 

Through  the  middle  of  the  body  the  tubercles  showed  an  obscure  tendency  to 
group  themselves  in  twos. 

Starting  now  at  the  other  end  of  the  body,  the  hindermost  tubercle  was  a 
broad  flattish  and  rather  inconspicuous  affair,  whose  contour  did  not  differ  very 
much  from  that  of  the  remainder  of  the  cuticle  on  the  right  side  of  the  tail.  This 
posterior  tubercle  lay  slightly  in  front  of  the  anus.  The  penultimate  and  ante- 
penultimate tubercles  were  rounded  and  closely  resembled  the  majority  of  the 
middle  members  of  the  series,  though  they  differed  in  presenting  more  clearly 
the  subordinate  minute  tubercles  on  their  surfaces.  Here  too,  in  some  cases,  it 
was  possible  to  demonstrate  the  presence  of  refractive  elements — perhaps  nerve' 
elements— passing  to  the  subsidiary  tubercles.  Behind  the  flattish  posterior 
tubercle  the  general  character  of  the  cuticle  of  the  right  side  was  maintained  to 
near  the  terminus,  and  the  arrangement  was  such  that  the  posterior  extremity 
appeared  as  if  somewhat  unequally  bifurcated,  one  fork  being  the  terminus 
proper,  that  is,  the  end  of  the  tail,  the  other  being  the  slightly  arcuate  out- 
turned  loose  terminal  portion  of  the  dexter  cuticular  armament. 

The  lip  region  is  a  rather  prominently  expanded  markedly  asymmetrical  struct- 
ure. The  flexibility  of  the  neck  enables  the  lip  region  to  be  swung  with  com- 
parative rapidity  back  and  forth  through  an  angle  of  nearly  ninety  degrees. 
There  are  six  tapering,  spreading,  nearly  straight  cephalic  setae,  arranged  in 
very  unequal  pairs,  a  left  submedian  slender  pair,  one  dorsally  submedian,  the 
other  ventrally  submedian ;  a  large  pair,  correspondingly  arranged,  but  extending 
in  the  opposite  direction,  thus  appearing  to  be  right  submedian;  and  a  very  small 
right  submedian  pair.  The  members  of  the  large  pair  are  two  to  three  times  as 
long  as  those  of  the  left  hand  pair;  these  latter  being  about  one-third  as  long  as 
the  pharynx,  whereas  the  former  are  more  than  halt  as  long  as  the  pharnyx. 
The  right  submedian  setae  are  reduced  and  papilla-like.  Each  of  these  six  setae 
has  a  swollen  or  even  bladder-like  base,  which  is  very  much  more  pronounced  in 
the  case  of  the  largest  setae.  The  dexter  labial  tubercle  is  located  between  the 
two  small  right-hand  setae.  Between  these  latter  and  the  larger  setae  there 
may  usually  be  seen  two  or  three  exceedingly  delicate  refractive  elements  some- 
what suggestive  of  the  repetitive  elements  in  the  nematode  genus  Wilsonemq; 
these  are  beyond  question  connected  with  the  largest  setae.  Between  the  left 
submedian  setae,  that  is  to  say,  on  the  left  lateral  line,  careful  focusing  shows  in 
the  optical  longitudinal  section  of  the  head  what  appears  to  be  a  minute  pore, 
ending  in  a  depression  on  the  outer  surface  of  a  minute  labial  elevation.  On 
each  side  of  this  "pore"  are  two  minute  papillae,  corresponding  to  two  similar 
ones  on  the  right  side  of  the  head.  Between  the  left-hand  setae  and  papillae 
and  the  border  of  the  mouth  opening,  there  is  a  thin  semi-circular,  curved,  pro- 
jecting oral  membrane,  extending  forward  and  outward.  This  membrane  is  wid- 
est, that  is,  extends  farthest  forward,  in  the  lateral  region,  and  at  this  point  its 
altitude  is  somewhat  less  than  the  length  of  the  left-hand  setae.  At  their  bases, 
which  are  relatively  broad,  the  setae  are  inflated,  more  especially  the  largest  ones, 
and  are  so  set  on  the  margin  of  the  head  that  their  proximal  parts  produce  a  very 
pronounced  shoulder.  The  rather  narrow  triquetrous  pharynx,  which  ends 
abruptly  at  the  base,  is  of  equal  diameter  throughout,  and  has  a  length  about 
equal  to  the  diameter  of  the  head  measured  opposite  its  base;  it  is  entered  through 
a  rather  narrow  mouth  opening.  The  anterior  end  of  the  oesophagus  receives  the 


110  ASYMMETRY   OF   THE    NEMATODE 

base  of  the  pharynx.  The  oesophagus  begins  as  a  tube  about  half  as  wide  as  the 
corresponding  portion  of  the  neck.  It  continues  to  have  this  diameter,  or  a 
slightly  greater,  until  near  the  middle  of  the  neck  it  expands  to  form  the  median 
swelling,  which  is  nearly  two-thirds  as  wide  as  the  corresponding  portion  of  the 
neck,  and  has  a  distinct,  simple,  elongated,  chitinous  valvular  apparatus,  the 
length  of  which  is  nearly  equal  to  the  corresponding  radius  of  the  neck.  Behind 
this  bulb  the  oesophagus  diminishes  suddenly  in  diameter  so  that  it  is  only  one- 
fourth  as  wide  as  the  corresponding  portion  of  the  neck.  It  finally  expands  to 
form  the  pyriform  cardiac  bulb,  which  is  twro-thirds  as  wide  as  the  base  of  the 
neck,  and  contains  a  distinct,  three-fold,  more  or  less  complicated,  non-striated 
valvular  apparatus.  The  intestine  becomes  at  once  three-fourths  as  wide  as  the 
body.  There  is  an  obscure  flattish  cardia  a  little  more  than  one-third  as  wide  as 
the  corresponding  portion  of  the  body.  The  cells  of  the  intestine  contain  a  few 
scattered  granules  of  variable  size,  the  largest  of  which,  fatty  granules,  are  rela- 
tively large  and  have  a  diameter  nearly  equaling  that  of  the  pharynx;  the  small- 
est, probably  of  another  character,  being  very  much  smaller.  They  are  less 
numerous  and  smaller  toward  the  posterior  part  of  the  intestine.  Xo  doubly  re- 
fractive granules  have  been  seen.  The  lining  of  the  intestine  is  somewhat  re- 
fractive, so  that,  especially  toward  the  middle  of  the  body,  the  sinuous  lumen  is 
often  quite  a  distinct  feature.  The  excretory  pore  is  somewhat  behind  the  middle 
of  the  neck.  The  tail  end  begins  to  taper  from  some  distance  in  front  of  the 
anus,  and  tapers  at  about  the  same  rate  until  after  it  passes  the  anus,  where  it 
soon  begins  to  taper  more  rapidly,  so  that  the  posterior  somewhat  concave  conoid 
half  of  the  tail  is  relatively  narrow,  and  the  terminus  itself  hairfine.  The  diame- 
ter of  the  tail  at  the  middle  is  about  one-sixth  as  great  as  at  the  anus.  From  the 
rather  prominent,  salient,  two-lipped  vulva  the  vagina  leads  inward  at  right 
angles  to  the  ventral  surface  nearly  halfway  across  the  body.  A  mature  ovum 
is  about  as  long  as  the  body  is  wide,  and  fully  one-third  as  wide  as  long,  and  there- 
fore of  such  a  size  as  to  indicate  that  each  uterus  can  probably  contain  only  one 
egg  at  a  time. 

5.3  19.      28.      'M45-        88. 

4.4  5.5     6.3      6.5        4.8  '    The  tail  of  the  male  is  like  that  of  his  mate 
in  form  and  size,  though  it  tapers  more  regularly.     The  two  equal,  uniform,  long 
and  very  slender,  slightly  arcuate,  colorless,  inconspicuous  spicula  are  about  two 
and  one-half  times  as  long  as  the  anal  body  diameter.     Their  proximal  ends  are 
slightly  cephalated  by  expansion.     They  are  accompanied  by  a  more  plainly  visi- 
ble, simple,  somewhat  wider,  slightly  colored  accessory  piece  wrhich  is  nearly 
straight,  and  about  half  as  long  as  themselves.     Springing  from  a  little  in  front 
of  the  anus  there  is  a  very  weakly  developed  or  rudimentary  almost  invisible 
bursa,  whose  somewhat  asymmetrically  arranged  ribs  or  papillae,  difficult  of 
observation,  are  located  as  follows : 

Almost  exactly  on  the  ventral  line,  in  front  of  the  anus,  at  a  distance  from  it 
equal  to  the  corresponding  body  diameter,  there  is  a  circular  marking  (r,  Fig. 
1),  which  is  larger  than  any  other  marking  of  this  character,  and  seems  to  repre- 
sent one  of  the  male  papillae.  To  the  right  of  it,  and  a  trifle  behind  it,  rather 
nearer  the  right  submedian  line,  is  another  papilla  of  similar  character,  slightly 
smaller.  Opposite  the  anus,  on  the  left  submedian  line,  there  is  a  small  papilla; 
the  mate  of  this  on  the  right  submedian  line  (M),  seems  to  be  in  the  border  of  the 


BUNONEMA    IMPAR  HI 

thickened  dexter  cuticle,  and  is  a  little  larger.  Slightly  in  front  of  the  anus, 
and  near  the  median  line,  both  on  the  left  and  on  the  right,  there  is  a  papilla  (s), 
that  on  the  right  being  a  little  the  larger,  and  not  quite  so  near  the  median  line, 
but  still  outside  the  dexter  cuticle.  A  little  behind  the  middle  of  the  tail  there 
is  a  submedian  pair  (<;),  of  which  the  right  hand  one  is  in  the  edge  of  the  thick- 
ened dexter  cuticle,  while  the  left  hand  one  is  very  inconspicuous  and  somewhat 
farther  forward.  Considerably  farther  back  there  is  a  group  of  about  eight 
papillae,  (w,  x,  y),  arranged  in  four  pairs,  some  of  which  are  exceedingly  obscure. 
The  anterior  pair,  (w),  is  ventrally  submedian.  This  pair  is  followed  by  two  dor- 
sally  submedian  pairs,  (x),  nearly  opposite  to  which  is  a  ventral  pair,  (y),  one 
nearly  in  front  of  the  other.  It  will  be  noted  that  these  supplementary  organs 
are  arranged  much  as  in  some  species  of  Cephalobus. 

The  ejaculatory  duct  is  about  two-fifths  as  wide  as  the  body.  It  has  the 
same  width  as  the  single  testis,  whose  reflexed  blind  end  is  located  not  far  behind 
the  base  of  the  oesophagus,  and  extends  backward  a  distance  about  equal  to  the 
length  of  the  body  diameter. 

Habitat.  Found  in  the  rotting  wood  of  red  oak,  Washington,  D.  C.,  by  Dr. 
Howard  Crawley. 

5.3     18.      26.       'M58.       90. 

2.  Bunonema  impar,  n.  sp.  sTs  <U  <Ti  T!  si  '32  mm'  On  the  right  hand 
side  there  are  two  rows  of  yellowish  tubercles,  each  row  consisting  of  about 
eighteen  to  twenty  members.  The  lip  region  bears  a  somewhat  thumb-shaped 
lateral,  more  or  less  forward-pointing,  protuberance  which  is  probably  homolo- 
gous with  the  dextral  tubercles.  Opposite  the  base  of  the  pharynx  is  a  single 
tubercle,  the  first  genuine  pair  of  the  lateral  series  being  a  little  in  front  of  the 
median  bulb;  thence  backward  all  the  tubercles  are  in  somewhat  irregular  pairs, 
except  one  or  two  of  those  near  the  tail  end.  The  members  of  each  pair  are  placed 
side  by  side.  These  tubercles  are  rounded  elevations  having  a  height  about 
equal  to  the  width  of  eight  of  the  annules  of  the  cuticle.  When  the  nematode  is 
in  a  straightened-out  attitude  the  distance  between  the  pairs  of  tubercles  is 
about  equal  to  their  width.  The  posterior  tubercles  tend  to  run  together,  and 
are  slightly  lower  and  flatter  than  the  anterior.  The  anterior  tubercles,  especi- 
ally those  on  the  neck,  are  capped  with  slightly  thickened,  rather  uniform  chitin, 
which  bears  extremely  minute  markings  similar  to  those  noted  on  Bunonema 
inequale.  The  face  of  the  tubercles  appears  punctate,  though  on  focusing  deeper 
they  appear  striated.  The  lip  region  is  very  similar  to  that  of  Bunonema  inequale. 
The  largest  setae  are  of  about  the  same  size  and  proportions  as  in  inequale,  as 
are  also  the  ventrally  submedian  setae,  though  the  latter  are  hardly  inclined  to 
be  inflated  at  the  base.  Between  the  papillae  there  seem  to  be  structures  very 
similar  to  those  of  inequale.  When  seen  from  the  right  side  the  adjacent  lip  region 
presents  the  following  appearances:  the  two  setae  with  saccate  bases  appear  to 
be  nearly  at  right  angles  to  each  other,  and  have  their  tips  located  at  a  distance 
from  each  other  equal  to  the  length  of  the  pharynx.  Each  of  these  setae  is  about 
three-fourths  as  long  as  the  chitinous  portion  of  the  pharynx.  Between  these 
two  setae  is  the  very  pronounced,  concave-conoid,  blunt,  rather  forward-point- 
ing, almost  thumb-shaped  protuberance  already  mentioned,  which  is  probably 
homologous  with  the  lateral  tubercles,  though  it  presents  little  or  none  of  the 
brownish  or  yellowish  coloration  characteristic  of  the  tubercles.  On  each  side 


112  ASYMMETRY   OF   THE    NEMATODE 

of  this  lateral  protuberance  there  is  a  rounded  innervated  papilla,  which  breaks 
the  contour  of  the  curved  line  between  the  protuberance  and  the  adjacent  seta. 
On  the  lateral  line  opposite  the  base  of  the  protuberance  there  seems  to  be  a 
third  papilla  of  the  same  character  as  the  two  last  described.  The  head  is  sepa- 
rated from  the  neck  by  a  very  distinct  constriction.  Where  the  somatic  cuticle 
ends,  a  little  in  tront  of  the  middle  of  the  pharynx,  there  is  a  rather  distinct 
shoulder,  and  from  this  shoulder  the  diameter  decreases  rapidly  to  the  base  of 
the  lips  opposite  the  anterior  end  of  the  chitinous  portion  of  the  pharynx.  Here 
the  diameter  is  only  about  three-fifths  as  great  as  at  the  shoulder  before  men- 
tioned. The  saccate  basal  portions  of  the  large  apparently  dextral  setae  extend 
backward  somewhat  from  the  collum  or  constriction  separating  the  lip  region 
from  the  neck.  Viewed  from  the  left  side  the  left  submedian  setae  are' seen  to 
be  not  inflated  at  the  base.  Three  labial  papillae  are  also  to  be  seen  from  this 
side,  one  lateral  and  two  submedian.  These,  together  with  those  seen  on  the 
right  side,  complete  the  complement  of  six  minute  and  very  inconspicuous  labial 
papillae  encircling  the  head.  Th,ere  is  no  forward-pointing  thin  semicircular 
border  to  the  mouth  opening,  as  in  inequale.  The  pharynx  is  triquetrous,  and 
about  as  long  as  the  posterior  bulb,  or  a  little  longer,  in  other  words  about  one 
and  one-third  times  as  long  as  the  diameter  of  the  head  measured  opposite  the 
base  of  the  pharynx.  As  seen  in  optical  longitudinal  section  the  pharynx  is  about 
one-sixth  to  one-eighth  as  wide  as  long.  Its  cross-section  is  somewhat  similar 
to  that  of  the  oesophagus;  in  other  words,  it  is  not  prismoid,  and  yet  is  more  or 
less  triquetrous;  each  of  the  angles  is  composed  of  a  thin,  refractive,  simple,  chi- 
tinous element.  The  mouth  opening  is  hardly  wider  than  the  pharynx.  There 
are  one  or  two  innervated  papillae  on  the  dorsal  side  of  the  tail  near  the  rectum. 
Nothing  is  known  concerning  the  female  sexual  organs,  but  from  the  rudiments 
seen  in  male  specimens  which  probably  have  yet  to  undergo  a  final  moult,  it  seems 
clear  that  the  testis  is  single  and  has  its  blind  end  reflexed  a  distance  about  equal 
to  the  diameter  of  the  body. 

Habitat.  Found  with  Bunonema  inequale  in  the  rotting  wood  of  red  oak. 
Bunonema  impar  is  very  closely  related  to  Bunonema  inequale,  and  may  indeed 
prove  to  be  merely  a  variety  of  that  species. 

3.  Bunonema  dactylicum,  n.  sp.  Species  with  about  the  same  dimensions  and 
form  as  the  two  preceding.  As  only  the  young  forms  have  been  seen  it  remains 
somewhat  uncertain  whether  the  thickened  dextral  cuticle 
bears  tubercles,  but  i1  is  believed  not.  The  cuticle  is  tessel- 
lated and  striated  as  in  the  first  species  described.  The  two 
large  saccate  setae  are  arranged  very  much  as  in  B.  inequale, 
and  there  is  a  dextral  labial  "tubercle"  as  in  that  species. 
The  left  submedian  appendages  are  palmate,  as  shown  in 
Figure  2,  and  have  about  five  finger-shaped  processes.  In- 
side the  saccate  setae  is  a  forward-pointing,  more  slender 
pair  of  equal  length. 

Head  of        Habitat.     Found  in  the  rotting  wood  of  red  oak,  with  the 
n  a  dactylicum,   two  preceding,  Washington,  D.  C.,  U.  S.  A. 

n.  sp. 

May,  1915 


SELACHINEMA 


A  NEW  NEMATODE  GENUS  WITH   REMARKABLE 
MANDIBLES. 

BY  N.  A.  COBB 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY,  IV 

SELACHINEMA,  new  genus. 

Body  slender;  cuticle  finely  transversely  striated;  head  armed  with 
powerful  non-retractile  dentate  chitinous  mandibles;  amphids  spiral; 
tail  armed  with  caudal  glands  and  spinneret;  oesophagus  plain;  renette 
present;  minute  pores  on  the  lateral  lines. 


3.7 


9.0 
8.1 


49Y 


89. 
T.2 


Selachinema  ferox,  n.  g.,  n.  sp.  3.1     3.1     3.1      3.4      2.2  "  The  rather  thin 

layers  of  the  transparent,  practically  naked  cuticle  are  traversed  by  exceedingly 

fine  transverse  striae  resolvable 
only  with  the  aid  of  the  highest 
powers  under  favorable  condi- 
tions. Only  a  very  few  minute 
hairs,  hardly  more  than  twice 
as  long  as  the  cuticle  is  thick  are 
to  be  found  on  the  body.  The 
cylindroid  neck  ends  in  a  head 
which  diminishes  in  size  very 
slightly  just  beyond  the  am- 
;  phids,  and  bears  three  (?)  large, 
solid,  slightly  inwardly  arcuate, 
projecting,  powerful  chitinous 
jaws  armed  on  the  inner  surface 
with  four  longitudinal  rows  of 
somewhat  backward  pointing 
conical  teeth,  each  row  consist- 
ing of  four  or  five  teeth.  Each 
f  of  the  two  submedian  jaws  is 
composed  of  two  parts  of  une- 
qual size,  that  toward  the  dor- 
sal side  being  the  shorter,  and 
armed  with  two  rows  of  teeth 

Fig.  1.     Selachinema  ferox,  n.g.,  n.sp.     a,  the  two  power-  . 
ful  submedian  chitinous  jaws,  each  armed  with  tour  rows  of  OI   about  equal   Size,   Whllje   one 
retrorse  teeth ;  b,  rudiment  or  remnant  ot  ventral  jaw;  c,  lateral  f    .,        .          rr.wa   nn    tv,p    othpr 
setae  (restoration) ;  rf.  submedian  setae  (restoration)-behind  «'    tne   two   TOWS   on    tne    Otner 
may  be  seen  two  ot  the  tour  small  subceohalic  setae;  e,  spiral  nalf    of    the    mandible    is    COm- 
amphids; /,  base  ot  the  pharynx.     The  head  is  a  correct  cam- 
era lucida  drawing.    The  body  and  tail  have  been  drawn  in  posed    of    exceedingly    minute 

perspective  dotations.     Between  the  two 

113 


114  SELACHINEMA 

unequal  halves  of  the  mandible  is  a  thin,  arcuate,  toothless  element,  which  ends  in 
an  incurved  point  forming  the  distal  end  of  the  mandible.  The  chitinous  project- 
ing portion  of  these  jaws  is  slightly  inwardly  arcuate:  Each  jaw  is  somewhat 
longer  than  the  head  is  wide,  although  the  projecting  portion  is  only  about  half  as 
long  as  the  head  is  wide.  These  jaws  are  permanently  extended,  and  cannot  be 
withdrawn  into  the  pharynx.  They  are  used  in  a  manner  somewhat  like  that  of 
the  projecting  mandibles  of  certain  insects.  It  appears  as  if  a  dorsal  jaw  or 
mandible  had  been  broken  away  from  the  only  specimen  so  far  seen — a  young  one. 
There  is  a  circlet  of  cephalic  setae  opposite  the  base  of  the  chitinous,  extended  por- 
tion  of  the  jaws.  There  are  six  of  these  setae  in  one  circlet,  and  behind  each  of 
the  submedian  setae  of  this  circlet  there  is  a  smaller  seta  slightly  farther  back  so 
that  the  total  number  of  the  cephalic  setae  may  be  said  to  be  ten.  The  length  of 
the  six  main  setae  is  unknown,  as  they  are  all  broken  away  from  the  only  specimen 
hitherto  seen.  A  restoration  of  these  six  main  setae  is  attempted  in  the  illustra- 
tion; hence  these  setae  are  shown  by  means  of  dotted  lines.  The  spiral  amphids 
consist  of  about  three  and  one-half  winds,  and  are  nearly  half  as  wide  as  the  head, 
and  are  placed  opposite  the  base  of  the  pharynx,  their  anterior  borders  being 
about  half  as  far  from  the  anterior  extremity  as  are  the  bases  of  the  before-men- 
tioned naked  chitinous  portions  of  the  jaws.  There  are  no  eye-spots.  The  phar- 
ynx is  of  the  form  consonant  with  the  strongly  developed  jaws,  that  is  to  say,  it 
is  triangularly  concave-pyramidal.  Its  base  is  rather  plainly  indicated  by  the 
proximal  ends  of  the  chitinous  roots  of  the  jaws,  and  lies  opposite  the  posterior 
borders  of  the  amphids.  The  oesophagus  begins  as  a  tube  about  two-fifths  as 
wide  as  the  base  of  the  head,  and  continues  to  have  this  diameter  throughout  the 
greater  portion  of  its  length.  It  is  separated  from  the  oesophagus  by  a  constric- 
tion. There  is  no  bulb  and  there  does  not  appear  to  be  any  distinct  cardia.  The 
intestine,  which  is  made  up  of  cells  of  such  a  size  that  probably  four  to  six  are 
required  to  build  a  circumference,  is  rather  thick-walled.  The  small  granules  in 
the  cells  are  of  rather  uniform  size,  and  do  not  give  rise  to  any  distinct  tessella- 
tion. The  rectum  appears  to  be  shorter  than  the  anal  body  diameter.  The 
tail  is  convex-conoid  in  the  anterior  part  in  such  fashion  that  at  a  distance  from 
the  anus  at  least  as  great  as  the  anal  body  diameter,  it  has  diminished  so  that  it 
is  only  about  one-eighth  as  wide  as  at  the  anus.  Thence  onward  it  is  nearly 
cylindroid,  although  it  still  diminishes  slightly  in  diameter.  It  ends  in  a  slightly 
swollen  terminus  bearing  a  slightly  elongated,  plain,  unarmed  spinneret.  It 
seems  likely  that  the  tail  is  prehensile.  The  caudal  glands  are  located  in  the 
vicinity  of  the  anus.  The  renette  cell  lies  opposite  the  cardiac  constriction,  and 
is  somewhat  dumbbell  shaped,  and  placed  transversely;  the  slender  duct  leads 
forward  from  it,  and  connects  with  the  prominent  pyriform  ampulla,  which  is 
one-fourth  as  wide  as  the  corresponding  portion  of  the  neck,  and  this  in  turn 
leads  to  the  excretory  pore  near  by,  opposite  the  nerve-ring.  This  latter  sur- 
rounds the  oesophagus  somewhat  squarely.  In  front  of  the  exceedingly  incon- 
spicuous anus  there  are  two  lateral  rows  of  seven  or  eight  minute,  equidistant 
pores.  These  occupy  a  space  about  equal  to  twice  the  length  of  the  corresponding 
body  diameter.  The  distance  between  these  small  circular  organs  is  three  to 
four  times  as  great  as  the  diameter  of  one  of  them.  They  appear  merely  to 
penetrate  the  cuticle,  so  that  the  extejit  of  their  chitinous  outlines  in  a  radial 
direction  is  about  equal  to  their  width.  There  are  three  or  four  similar  pores  on 


A   NEW   NEMATODE    GENUS  115 

each  lateral  line  opposite  the  posterior  end  of  the  oesophagus,  occupying  a  dis- 
tance equal  to  the  body  radius.  Nothing  is  known  concerning  the  sexual  organs, 
as  the  description  is  derived  from  a  single  immature  specimen. 

Habitat.  Found  on  calcareous  algae,  near  low-tide  mark,  Colon,  Panama; 
where  it  was  feeding  on  other  nematodes. 

Selachinema  seems  without  doubt  to  belong  to  the  family  Enoplidae, 
which  may  now  be  defined  as  follows:  Free-living,  marine,  carnivorous 
nematodes  with  three  mandibles;  head  armed  with  setae  and  papillae; 
body  naked;  cuticle  transversely  striated,  sometimes  also  obliquely 
striated;  oesophagus  plain;  intestine  with  a  variety  of  well-developed 
specialized  cells  indicating  definite  division  of  digestive  functions; 
renette  and  caudal  glands  present ;  male  and  female  sexual  organs  double, 
spicula  two,  equal;  amphids  usually  small,  inconspicuous,  oval  or  spiral. 

The  following  genera  may  be  included  in  the  family:  1.  Demonema, 
Cobb  2.  Enoploides,  Ssaweljev  3.  Enoplolaimus,  de  Man  4.  Eno- 
plus,  Dujardin — type  genus  5.  Labyrinthostoma,  Cobb  6.  Selachi- 
nema, Cobb  7.  Triodontolaimus,  de  Man. 

The  sub-family  Enoplinae  should  contain  Enoplus,  Enoplolaimus, 
Enoploides  and  Labyrinthostoma;  the  sub-family  Selachineminae,  Se- 
lachinema. Demonema  and  Triodontolaimus  probably  represent  dis- 
tinct sub-families.  There  is  probably  confusion  of  characters  in 
Enoplolaimus,  Enoploides  and  Labyrinthostoma,  and  it  may  become 
necessary  to  rearrange  the  species  now  included  under  these  generic 
names. 

Enoplidae  occur  in  all  parts  of  the  world,  the  following  being  the 
present  known  geographical  distribution  of  the  various  genera. 

Demonema Italy,  California  Labyrinthostoma Ceylon 

Enoploides . .  Arctic,  Massachusetts  Selachinema Panama  (Colon) 

Enoplolaimus Cosmopolitan  Triodontolaimus  .English  Channel 

Enoplus Cosmopolitan 

Demonema,  Enoplus  and  Selachinema  all  contain  species  known  to 
devour  other  nematodes.  The  granules  in  the  intestinal  cells  of  the 
Enoplidae  give  rise  to  the  rather  distinctly  tessellated  appearance  which 
I  have  observed  to  be  more  or  less  characteristic  of  the  free-living 
nematodes  which  feed  upon  animal  organisms,  or  at  least  those  which 
feed  in  whole,  or  in  part,  upon  other  nematodes.  The  following  de- 
scription, derived  from  the  examination  of  an  Enoplus  whose  intestine 


1 16  SELACHINEMA 

contained  nematode  remains,  indicates  characteristics  of  these  carniv- 
orous species. 

The  cells  of  the  intestine,  separated  from  each  other  by  thin  refrac- 
tive walls,  had  the  form  of  rather  regular  polyhedrons,  and  each  con- 
tained a  distinct  subspherical  nucleus  having  a  diameter  about  one- 
third  as  great  as  that  of  the  cell  itself.  This  nucleus  was  supplied 
with  a  distinct  nucleolus.  Between  its  nucleus  and  the  wall  each  cell 
contained  a  large  number  of  brownish-yellow  spherical  granules  of 
somewhat  variable  size,  the  largest  having  a  diameter ,  one-fourth  to 
one-fifth  as  great  as  that  of  the  nucleus,  and  the  smaller  varying  from 
this  size  downward.  These  granules  had  a  tendency  to  gather  next 
to  the  intestinal  lumen.  The  nucleus,  therefore,  lay  nearer  the  outer 
surface  of  the  intestine  than  the  inner.  In  the  anterior  part  of  the 
intestine  all  the  cells  except  the  cardiac  cells  had  the  same  character. 
Through  the  middle  of  the  body  the  intestinal  cells  varied  from  those 
in  the  anterior  part  of  the  body  in  that  the  granules  were  somewhat 
smaller,  and  less  numerous,  so  that  the  clear  spaces  in  the  cells  had 
relatively  greater  volume.  Behind  the  middle  of  the  body  certain  of 
the  cells  constituting  the  wall  of  the  intestine  were  markedly  different 
from  those  just  described,  although  these  latter  continued  to  consti- 
tute the  main  portion  of  the  intestinal  wall.  These  markedly  differ- 
entiated cells  were  twice  as  large  as  the  others  and  contained  larger- 
granules  of  more  uniform  size.  One  of  these  larger  cells  may  be  most 
advantageously  examined  when  it  occurs  opposite  the  lateral  field, 
where  the  refractions  due  to  the  muscular  cells  of  the  body  wall  do 
not  interfere  with  the  view.  It  may  then  be  seen  to  have  an  elliptical 
contour,  at  least  when  seen  face  view,  and  to  contain  a  nucleus  half  as 
wide  as  itself.  The  nucleus  in  turn  contains  a  nucleolus  having  a 
diameter  one-third  as  great  as  its  own.  The  total  number  of  granules 
in  one  of  these  giant  cells  was  between  50  and  100,  and  owing  to  the 
relatively  large  size  of  the  nucleus  they  were  located  more  particularly 
toward  the  ends  of  the  cell.  The  granules  were  of  rather  uniform 
size  and  had  a  diameter  about  twice  as  great  as  that  of  the  largest 
granules  in  the  ordinary  intestinal  cells.  There  were  20  to  30  of  these 
scattered  giant  cells  in  the  posterior  fourth  of  the  intestine. 


May,  1915 


NOTES  ON  NEMAS* 

(1)  Segmentation  of  Their  Organs,  Illustrated  by  three  new  free-living  marine 

genera.  (2)  Intravitam  Color  Reactions,  (3)  the  Nema  population  of  Beach 

Sand,  (4)  Locational  Terms  for  the  Cytology  of  Descent,  and 

(5)  Functions  of  the  Amphids. 


By  N.  A.  COBB 
CONTRIBUTIONS  TO  A  SCIENCE  OP   NEMATOLOGY  V 

1 
SEGMENTATION  IN  NEMATODES 

OBSERVATIONS  BEARING  ON  THE  UNSETTLED  QUESTION  OF  THE 

RELATIONSHIP  OF  NEMATODES  TO  OTHER  BRANCHES  OF 

THE  ANIMAL  KINGDOM 

I  have  long  been  impressed  by  certain  evidences  of  segmentation 
in  nematodes.  My  first  impressions  arose  from  a  study  of  the  dis- 
tribution of  the  setae  on  aquatic  forms.  This  distribution  was  in 
those  days,  and  is  even  yet,  described  as  irregular;  the  setae  are  said  to 
be  "scattered"  on  the  body.  Charting  all  the  setae  on  a  given  speci- 
men led  to  the  conclusion  that  they  were  not  scattered  ("  zerstreut") ; 
that,  rather  on  the  contrary,  they  constituted  a  series  of  more  or  less 
harmonious  groups.  The  cephalic  setae,  it  is  well  known,  have  an 
orderly  arrangement.  The  study  of  a  large  number  of  cases  leads  me 
to  the  conclusion  that  those  setae,  some  distance  behind  the  cephalic 
setae,  denominated  subcephalic  setae,  are  also  orderly  in  arrangement, 
and  might,  in  some  instances  at  least,  be  regarded  as  repetitive  of  the 
cephalic  setae. 

Later  I  was  able  to  show  that  the  transverse  striae  of  the  cuticle 
are  retrorse  on  the  posterior  half  of  the  body,  and  the  reverse  on  the 
front  half.  (See  Fig.  1.) 
This  reversal  in  the  cuticle 
at  the  middle  of  the  body, 

Or    thereabouts,    OCCUrS    in         Fig.  1.    Diagram  of  the  reversal  of  the  striae  of  the  cuticle 
.,  ..  of  a  nematode.    The  reversal  is  shown  just  above  the  letter  F. 

a  very  wide  range  of  gen- 
era, is  independent  of  age  and  of  sex,  and  seems  a  character  of  funda- 
mental significance. 


•Waverly  Press,  Baltimore,  May  8,  1917. 

117 


118 


NOTES  OX  XEMAS 


Recently  I  have  discovered  that  the  principal  cephalic  organs  are 
made  up  of  segments  which,  while  simple  in  character,  bear  no  small  re- 
semblance to  correspond- 
ing features  in  segmented 
organisms.  The  nature  of 
these  segmented  append- 
ages will  be  more  easily 
understood  by  consulting 
the  illustrations  in  Fig.  2. 
The  articulations  in  the 
TJ&&«£K«S£25^^  cephalic  organs  of  nemas 

are  not  easy  to  discover, 

owing  to  the  small  size  of  the  organs  and  the  transparency  of  the  tissues. 
Some  of  these  segmented  organs  are  under  muscular  control,  and  can 
be  extended  and  inflexed. 

This  is  true  of  some  of  the  setcphyntr  [  (|  set  Jit  /]  J  set /pli  t'xt 
labial  organs,  which  un- 
fortunately are  usually  so 
small  as  to  be  difficult  to 
observe.  The  cephalic 
setae,  however,  are  larger, 
being  particularly  well  de- 
veloped on  some  marine 
forms,  and  in  this  case  ob- 
servation on  living  speci- 
mens affords  evidence  of 
the  articulations  when  they 
might  be  overlooked  if 
they  were  sought  by  other 
methods;  for  if  a  seta  is 
obstructed  it  takes  on  the 
attitude  natural  to  an  or- 
gan composed  of  flexible 
joints  and  more  or  less  in- 
flexible segments,  as  shown 
in  the  upper  illustration, 


.g.,   n.sp.,   a    nema    with 
bling  Cyatholaimus,  but 


.  Fig.  3.    Pomponema    mirabile    n 

Jig.    2.        Here    again,    Once      jointed    cephalic  organs,  and   resem 

with  3  onchi,  more  complicated  amphids,  long,  jointed, 
labial  palps,  wings  as  in  Spilophora,  spicula  as  in  Cyatholaim- 
us, with  20  chromadoroid,  male  supplementary  organs. 
Characters  of  P.  mirabile,  type  species,  given  in  the  illustra- 
tions  and  formula. 


. 
having  established  the  fact 

and    learned    hOW    tO    make 
.          .  .  . 

the  observations,  it  proves 

that  the  setae  of  a  wide  range    of  genera  are  jointed,    though  the 

number  of  segments  is  often  reduced  to  only  one  or  two. 


SEGMENTATION  OF  THEIR  ORGANS 


119 


One  recalls  that  a  number  of  observers  have  noted  the  presence 
of  longitudinal  series  of  repetitive  organs  in  the  lateral  fields  of  nem- 


sct  Cfh 


set  cph  subin 


Fig.  4.  Scaptrella  cincta  n.g. 
n.  sp.  1  and  2  illustrate  re- 
spectively the  inflexed  and  ex- 
tended attitudes  of  one  of  the 
jointed  mandibles.  Scaptrella 
has  the  general  appearance  of 
Axonolaimus  de  Man  '89,  but 
has  jointed  mandibles,  circular 
amphids,  a  single  ovary,  and 
spicula  with  only  faint  accesso- 
ries. No  supplementary  organs. 
Characters  of  S.  cincta,  type 
species,  given  in  formulae  and 
illustrations.  Formula  explain- 
ed on  p.  7. 

atodes,  though  attention  has  never  been  called  to  the  fact  that  these 
organs  on  opposite  sides  of  the  body  may  be  symmetrical  to  each 
other.  Sometimes  they  are  exactly  so. 

How  is  the  prominent  trilateral 
symmetry  of  the  nematode  head  to 
be  expressed  in  terms  of  bilateral 
symmetry?  Selachinema  and  Cheir- 
onchus  assist  in  answering  this  ques- 
tion. A  second  species  of  Selachi- 
nema, not  yet  described,  has  little  or 
no  trace  of  the  vestigial  dorsal  jaw 
present  in  S.  vorax  (p.  113),  so  that 
the  two  projecting  mandibles  become 
practically  lateral,  and  are  bilaterally 
symmetrical.  An  even  more  com- 
plete transformation  occurs  in  Cheir- 
onchus  (Fig.  5),  where  by  a  complete 
disappearance  of  the  dorsal  sector  of 
the  pharynx  the  submedian  ones 
have  become  truly  lateral.  In  both 
these  genera  the  resulting  transfor- 
mation to  a  two-jawed  animal  gives 
rise  to  symmetrical  mandibles,  acting  w 
from  side  to  side. 

It  WaS,  Of   COUrSe,  Conceivable   that 

any  such  transformation  might  take 

the  form  of  a  union  of  the  submedian        SS'J   formX!pecie8'  *lven 


Mi/til. 


Fig.  5.  Cheironchus  vorax  n.g.,  n.sp.,  a  nema 
hose  bilaterally  symmetrical  mandibles  have 
Arisen  from  the  ventrally  sub'median  sectors 
of  the  head  at  the  same  time  that  the  dorsal 
elements  of  the  pharynx  have  disappeared. 
Cheironchus  has  the  general  appearance  of  Selach- 


120  NOTES  ON  NEMAS 

sectors,  these  united  elements  then  acting  in  opposition  to  the  dorsal 
sector,  the  two  jaws  thus  developed  becoming  one  dorsal  and  one 
ventral.  There  is  no  evidence  of  such  a  transformation. 


INTRA  VITAM  COLOR  REACTIONS  IN  NEMAS 

We  have  slowly  come  to  have  great  confidence  in  the  specificity  of 
certain  physiological  actions.  The  known  cases  of  specificity  are 
relatively  few,  and  have  been  discovered  largely  by  accident.  We 
do  not  know  the  exact  nature  or  cause  of  this  specificity.  We  intro- 
duce into  an  organism  certain  substances,  and  definite  results  follow; 
about  the  only  thing  we  know  in  the  matter  is  that  these  definite  re- 
sults follow  with  certainty.  What  the  reactions  are  that  bring  about 
the  result  we  do  not  know.  Our  ignorance  is  so  great  that  even  our 
theories  are  very  vague.  In  such  cases,  if  only  we  could  see  what  it 
is  that  happens  while  it  is  happening,  it  seems  certain  that  important 
advances  would  be  made  in  our  knowledge  of  nutrition,  growth,  and 
decay, — of  physiology,  pathology  and  medicine. 

If  substances  giving  color  reactions  in  living  tissues  could  be  applied 
to  small,  transparent,  varied  and  highly  complex  living  organisms, 
under  circumstances  that  would  permit  microscopic  examination  while 
the  reactions  are  in  progress,  we  might  hope  for  more  light  on  this 
exceedingly  important  subject.  Experiments  I  have  made  lead  to 
the  belief  that  many  of  the  conditions  requisite  for  success  in  this 
line  of  investigation  can  be  much  better  realized  than  hitherto  by 
feeding  colored  substances,  notably  coal-tar  dyes,  to  free-living 
nematodes. 

These  minute,  transparent  animals  are  comparatively  highly  organ- 
ized; not  only  this,  but  also  extremely  varied  in  their  habitats  and 
mode  of  life.  Some  are  exclusively  vegetarian,  others  exclusively 
carnivorous,  and  others  omnivorous.  They  constitute  a  group  com- 
posed probably  of  hundreds  of  thousands  of  species,  embodying  an 
almost  inconceivable  number  of  kinds  of  physiological  action.  Their 
organs  are  enclosed  in  a  thin  transparent  cuticle,  and  are  strung  out 
so  as  to  make  them  unusually  suitable  for  intra  vitam  examination. 
Under  slight  pressure  the  nema  flattens  out  more  or  less  without  losing 
its  vitality  sufficiently  to  preclude  satisfactory  intra  vitam  exami- 
nation under  the  highest  powers  of  the  microscope. 


INTRA  VITAM  COLOR  REACTIONS  IN  NEMAS  121 

Observing  certain  precautions,  I  find  that  a  great  variety  of  coal-tar 
compounds  and  other  colored  compounds  can  be  fed  to  nemas,  ap- 
parently without  interfering  materially  with  their  normal  metabolism. 
Some  nemas  are  resistant  to  chemicals  that  to  most  organisms  are 
poisonous.  Often  I  have  had  the  best  results  by  cumulative  action, 
using  small  quantities  of  color  dissolved  in  the  medium  in  which  the 
nema  lived,  and  allowing  the  dye  to  act  for  days  or  weeks. 

Not  infrequently  the  dyes  prove  to  be  highly  specific  in  their  action. 
Only  certain  cells,  or  only  definite  parts  of  certain  cells,  exhibit  visible 
reactions  in  the  form  of  colorations.  The  results  obtained  by  the 
use  of  any  given  dye  may  be  quite  varied.  It  is  evident  in  many  cases 
that  the  dye  is  digested  and  assimilated,  thereby  undergoing  molec- 
ular changes  by  which  it  is  converted  into  new  compounds  in  a  man- 
ner analogous  to  the  processes  exemplified  in  chemical  laboratories 
devoted  to  the  production  of  aniline  dyes.  Thus,  a  dye  may  give 
rise  to  several  different  colors,  none  of  them  like  that  of  the  dye  itself, 
and  all  of  them  very  likely  due  to  new  compounds.  I  have  seen  con- 
siderable evidence  pointing  to  the  conclusion  that  in  some  cases  the 
dye  fed  is  converted  into  colorless  compounds  during  the  process  of 
digestion  (a  reduction  phenomenon?),  and  these  colorless  compounds 
re-converted  into  colored  substances  after  they  arrive  at  certain  des- 
tinations or  conditions.  The  number  of  changes  these  "living  lab- 
oratories" can  ring  on  the  molecular  structure  of  a  given  dye  must  in 
some  cases  be  very  considerable.  Two  or  more  dyes  fed  simultane- 
ously sometimes  produce  results  more  or  less  independent  of  each 
other.  The  spectacles  are  very  brilliant. 

Using  these  methods  I  have  been  able  to  demonstrate  within  the 
confines  of  a  single  cell  the  existence  of  an  unsuspected  number  of 
kinds  of  "granules,"  manifestly  playing  different  rdles.  After  the 
differences  among  these  bodies  have  been  shown  in  this  way,  it  is 
sometimes  possible  to  perceive  corresponding  morphological  differ- 
ences; but  without  the  aid  of  the  color  reactions  the  differences  "Would 
never  have  been  suspected. 

The  main  thing  to  bear  in  mind  is  that  on  the  basis  of  our  present 
more  complete  knowledge  of  the  chemical  and  physical  properties  of 
coal-tar  compounds  these  color  reactions  in  living  nemas  may  be  made 
the  index  of  physiological  characters  possessed  by  the  cells  and  their 
components.  In  view  of  the  great  variety  of  the  known  coal-tar 
derivatives,  and  the  wonderfully  varied  metabolism  of  the  free-living 
nemas,  it  seems  to  me  a  very  reasonable  hope  that  researches  directed 


122 


NOTES  ON  NEMAS 


along  this  line  will  lead  to  important  results,  and  that  the  nemas  may 
become  classical  objects  in  cell  and  general  physiology,  as  they  have 
already  become  in  sex  physiology. 

A  new  and  rather  extensive  nomenclature  will  become  necessary. 
It  will  be  needful  to  distinguish  between  the  results  of  intra  vitam, 
intra  mortem  and  post  mortem  staining;  for  these  three  terms,  the  last 
two  new  in  this  connection,  represent  as  many  different  phases  in  the 
reactions  that  take  place  during  the  course  of  the  experiments.  As 
the  cells  lose  vitality,  new  color  reactions  occur,  and  the  death  of  the 
cell  is  followed  by  further  equally  marked  changes  in  the  reactions. 
The  cell  elements  I  have  mentioned  vary  in  size,  but  most  of  them 
are  exceedingly  small,  many  so  small 
that  they  are  on  the  limits  of  visibility 
using  the  very  best  instruments  with 
the  greatest  skill  and  under  the  most 
favorable  conditions.  On  the  other 
hand,  some  of  them  are  large  enough 
so  that  they  can  be  examined  in  con- 
siderable detail  and  their  structures 
made  out.  Among  them  are  the  bodies 
currently  referred  to  under  the  name 
mitochondria,  and  other  more  or  less 
synonymous  words. 

As  it  will  be  some  time  before  we 
can  establish  a  rational  nomenclature 
for  these  numerous  intracellular  struc- 
tures it  is  desirable  meanwhile  to  adopt 
terms  that  will  permit  intelligent  dis- 
cussion of  our  discoveries  as  they  are  made.  While  the  principles  un- 
derlying such  a  nomenclature  are  easily  defined,  it  is  by  no  means 
easy,  in  the  present  condition  of  things,  to  suggest  suitable  short  and 
expressive  loots  to  be  used  as  a  basis.  In  the  long  run  there'll  be 
less  confusion  if  meanings  of  the  terms  first  employed  relate  to  form, 
size,  and  position  rather  than  function. 

Investigations  of  this  character  are  not  unlikely  to  stimulate  further 
research  in  connection  with  aniline  derivatives.  Present  efforts  are 
directed  toward  the  discovery  of  dyes  of  greater  or  less  permanency. 
Permanency,  however,  is  of  little  moment  in  these  investigations; 
what  is  of  moment  is  the  chemical  and  physical  nature  of  the  dyes. 
No  doubt  dyes  of  a  greater  range  of  composition  can  be  produced  if 


Fig.  6.     Diagram  of  a  pair  cf  objectives, 
the  lower  used  as  a  condenser  for  the  upper. 


INTRA  VITAM  COLOR  REACTIONS  IN  NEMAS  123 

permanency  be  disregarded.  Furthermore,  as  already  hinted,  color- 
less compounds  may  be  used  if  in  the  course  of  the  metabolism  they 
are  converted  into  colored  compounds.  The  results  of  recent  studies 
of  dyes  as  chemical  indicators  come  into  play,  and  give  valuable  evi- 
dence in  determining  acidity  and  alkalinity. 

I  am  almost  ready  to  express  the  opinion  that  a  small  army  of  in- 
vestigators should  be  engaged  on  the  problems  opened  up  in  this  way. 
The  equipment  needed  by  the  investigator  is  as  follows:  (1)  He  must 
be  a  good  microscopist,  versed  in  physiology,  cytology,  and  histology. 
(2)  He  should  be  conversant  with  the  chemistry  of  the  coal-tar  com- 
pounds, not  so  much  from  the  viewpoint  of  the  maker  of  dyes  as  from 
that  of  the  broad-minded  chemist,  freed  from  the  economic  domina- 
tion of  the  dye  industry,  for,  as  before  remarked,  fugitive  dyes,  and 
even  colorless  compounds,  are  possible  factors  in  such  investigations 
as  are  here  under  discussion.  (3)  He  should  have  a  working  knowl- 
edge of  nemas. 

ILLUMINATION 

In  order  to  distinguish  with  accuracy  among  intra  vitam  color  re- 
actions it  is  necessary  to  be  very  particular  about  illumination.  The 
most  perfectly  corrected  lenses  must  be  used,  both  as  condenser  and 
objective,  and  the  light  used  must  be  as  nearly  white  as  possible.  The 
best  source  of  light  known  to  me  for  these  researches  is  bright  sun- 
light reflected  from  a  plane,  matte,  white  reflector.  The  reflector 
should  be  several  feet  across,  and  placed  at  a  distance  from  the  micro- 
scope several  times  its  own  diameter.  It  should  be  universally  ad- 
justable, so  that  it  can  be  set  to  reflect  a  maximum  of  light  to  the  mir- 
ror of  the  microscope, — all  the  better  if  it  is  heliostatic.  A  good 
surface  for  the  screen  is  made  by  whitewashing  a  rather  finely  woven 
cotton  cloth. 

The  best  optical  arrangement  I  have  tried  is  the  use  of  one  apo- 
chromat  objective  as  a  condenser  for  another  apochromat.  I  have 

been      USing       With       s?uare  c^rff/ass       ^u^  eo^ry/aiss_ 

success  a  2  mm. 
apochromat  as  a 
condenser  for  a  2 

mm.    Or    1.5    mm.         Fig.  7.    Microscope  slide  used  for  intra  vitam  examinations  as  indicated 

apochromat     ob- 
jective.    These  precautions  are  necessary  if  fine  color  distinctions  are 
to  be  made  with  the  greatest  possible  accuracy.     If  these  precautions 


124  NOTES  ON  NEMAS 

are  taken,  it  will  be  found  that  fine  distinctions  can  be  made  with 
such  precision  as  to  dispel  all  doubt  as  to  the  existence,  side  by  side, 
in  the  same  cell,  of  bodies  of  quite  different  character  that  it  other- 
wise would  be  either  impossible  or  exceedingly  difficult  to  distinguish 
from  each  other. 

The  use  of  an  ordinary  apochromatic  objective  as  a  condenser  ne- 
cessitates the  use  of  a  special  object  slide,  consisting  essentially  of 
a  carrier,  and  two  cover  glasses.  The  object  is  mounted  between  the 
cover  glasses.  Such  a  slide  is  shown  in  the  accompanying  illustration. 
The  substage  of  the  microscope  should  have  a  centering  arrangement 
and  a  rack  and  pinion,  or  screw  focusing  adjustment.  A  little  ex- 
perience with  an  apparatus  of  this  sort,  in  which  all  known  precau- 
tions are  taken  to  remove  color  from  the  optical  system  leads  one 
to  distrust  the  ordinary  Abb6  substage  condenser  when  fine  distinc- 
tions are  to  be  made  between  colors  in  the  microscopic  object,  espe- 
cially if  the  colors  are  of  similar  character. 


NEMATODE  POPULATION  OF  BEACH  SAND 

Through  the  courtesy  of  the  U.  S.  Bureau  of  Fisheries  I  was  able  to 
make  quantitative  observations  during  the  summer  of  1916  on  the 
nemas  of  ordinary  beach  sand,  between  tide-marks,  at  Woods  Hole, 
Buzzard's  Bay,  U.  S.  A.  Nemas  were  plentiful;  it  was  calculated 
that  on  one  beach  in  the  top  3  inches  of  sand  there  were  at  least  527 
millions  per  acre.  On  another  beach  there  were  at  least  1040  millions 
in  the  topmost  inch  of  sand.  The  nemas  varied  from  a  fraction  of 
a  millimeter  to  10  millimeters  in  length,  averaging  2  to  3  millimeters. 
On  muddy  shores  where  organic  matter  is  more  abundant,  the  riema- 
tode  population  is  much  more  dense, — thousands  of  millions  per  acre. 

Many  of  these  nemas  were  strictly  vegetarian,  and  fed  on  micro- 
scopic plants  present  in  the  beach  sand, — plants  both  green  and  color- 
less. Experiment  showed  that  a  considerable  amount  of  light  pene- 
trates average  beach  sand  to  a  depth  of  f  inch,  thus  rendering  possible 
the  growth  of  green  protophytes  and  various  algae  at  slight  depths 
in  the  sand.  Some  of  the  nemas  were  strictly  carnivorous,  feeding  on 
protozoa  and  other  small  animals. 

On  trial  it  proved  that  the  top  layers  of  sand,  between  high  and  low 
tides,  under  ordinary  circumstances,  afford  the  nemas  a  habitat  of 
considerable  stability,  since  the  shifting  of  these  layers  during  the 


LOCATIONAL  TERMS,  CYTOLOGY  OF  DESCENT          125 

rise  and  fall  of  the  tides  is  so  little  as  to  interfere  in  no  way  with  the 
life  activities  of  the  nemas.  On  open  ocean  beaches,  where  the  force 
of  the  breakers  is  greatest  the  nemas  take  on  forms  and  acquire  habits 
that  protect  them  from  destruction, — a  tougher  cuticle,  and  the  habits 
of  burrowing  and  of  coiling  themselves  into  a  "ball." 

Beach  nemas  in  their  turn  are  devoured  by  the  larger  animals  dwell- 
ing in  and  on  the  sand,  and  thus  form  one  of  the  links  in  a  chain  from 
the  most  minute  forms  of  life  to  those  of  largest  size. 

Beach  nemas  lead  a  very  active  life,  winding  in  and  out  among  the 
grains  of  sand  as  do  snakes  in  a  pile  of  stones.  The  earth's  hundreds 
of  thousands  of  miles  of  beach  sand,  far  from  being  barren,  must  be 
reckoned  as  a  productive  area  of  some  little  importance. 


LOCATIONAL  TERMS  FOR  THE  CYTOLOGY  OF  DESCENT 

There  is  no  satisfactory  locational  terminology  connected  with  par- 
thenogenesis, hermaphroditism  and  bisexuality;  in  other  words,  with 
the  space  relationships  of  the  reproductive  cells  and  their  essential 
elements, — a  terminology  enabling  us  to  answer  succinctly  such  ques- 
tions as,  "How  are  these  cells  and  their  elements  located  with  reference 
to  each  other?"  Such  nomenclature  as  we  have  for  this  purpose  has 
accumulated,  bit  by  bit,  through  successive  contributions  of  more 
or  less  independent  investigators,  and,  naturally  enough,  has  become 
a  very  heterogeneous  mixture  of  terms  and  phrases. 

Aside  from  standing  open  to  the  criticism  of  being  inadequate  and 
an  incongruous  mixture,  such  terms  as  are  in  current  use,  at  least  a 
considerable  portion  of  them,  date  from  a  time  when  our  knowledge 
of  the  chromosomes  and  their  relationships  to  each  other  and  to  hered- 
ity was  either  non-existent  or  much  less  complete  than  at  present. 
Most  of  these  terms,  therefore,  are  based  on  the  assumption  that  the 
body  or  soma  is  the  principal  or  predominant  feature  of  the  organism, 
and,  philologically  speaking,  they  take  little  or  no  account  of  the  mod- 
ern view  of  the  importance  of  the  gametes  and  of  the  r61e  they  play. 

As  we  seem  in  need  of  a  more  adequate  and  homogeneous  set  of 
terms  based  on  the  relationship  to  each  other  in  space  of  the  gonads, 
the  gametes,  and  the  chromosomes  and  other  intra-cellular  elements, 
I  call  attention  to  the  following  series  of  terms,  positional  rather  than 
physiological,  I  have  been  using  to  meet  this  need:  Just  as  we  have 
"cone"  and  "conic"  evolved  from  the  Greek  KOVOS,  I  derive  the 


126  NOTES  ON  NEMAS 

words  "gone"  and  gome"  from  70^05.  Primarily  the  word  "gone" 
refers  to  the  generative  portion  of  a  sexual  organ.  By  metonomy 
"gone"  designates  an  organism  or  species  having  gones;  thus  we  have 
two  kinds  of  organisms — "gones"  and  "agones." 

From  "gone"  come  the  verb  "to  gone,"  and  the  substantives  "syn- 
gone,"  "digone,"  "amphigone,"  "homogone,"  and  "heterogone." 
From  syngone  come  the  words  "syngonic,"  syngonically,"  and  "syn- 
gony;"  and  corresponding  words  from  digone,  amphigone,  homogone 
and  heterogone. 

Gone.    To  produce  gones. 

Gonic.    Of  or  relating  to  a  gone. 

Syngonic.  Having  macro- ("female")  and  micro- ("male")  gametes  in  the  same 
gone;  e.g.  as  in  many  nemas. 

Digonic.  Having  macro- ("female")  and  micro- ("male")  gametes  in  separate 
gones  in  the  same  individual;  e.g.  as  in  many  hermaphrodites. 

Amphigonic.  Having  macro- ("female")  and  micro-("male")  gametes  in  sep- 
arate gones  that  are  in  separate  individuals;  e.g.  as  in  all  bisexual  forms. 

Homogonic.     Having  gones  all  of  the  same  kind. 

Heterogonic.  Having  gones  of  various  kinds;  e.g.  as  in  a  species  presenting 
both  syngony  and  amphigony. 

Syngone.  A  gone  bearing  both  macro-("female")  and  micro- ("male")  gametes. 
By  synecdoche  syngone  also  designates  an  organism  or  species  containing, 
or  characterized  by,  syngones;  similarly  with  the  following  four  terms. 

Digone.    A  digonic  individual  or  species. 

Amphigone.    An  amphigonic  species. 

Heterogone.  A  species  presenting  both  amphigony  and  syngony,  or  both  di- 
gony  and  amphigony,  etc.  A  heterogonic  species. 

Homogone.  A  species  or  individual  presenting  uniformity  in  the  space  rela- 
tionships of  its  gonic  cells.  A  homogonic  species. 

Kinetogone.    A  gone  whose  gametes  are  active,  aggressive,  or  "male." 

Statogone.    A  gone  whose  gametes  are  passive  or  "female." 

Entering  now  a  more  or  less  theoretical  domain  whose  permanency 
will  depend  on  the  results  of  future  investigations,  and  carrying  the 
analysis  a  step  farther  by  taking  into  consideration  the  space  relation- 
ships of  the  chromosomes  and  other  intra-cellular  elements  that  ac- 
cording to  an  increasingly  prevalent  modern  belief  themselves  carry, 
or  determine  the  factors  of  descent,  and  using  the  Greek  word  KVVTOS  as 
a  basis,  I  derive,  as  may  be  necessary,  "syncyst,"  "amphicyst,"  'het- 
erocyst,"  etc.,  and  their  adjective,  adverbial,  and  substantive  deriva- 
tives (  e.g.,  syncystic,  syncystically,  syncysty)  to  aid  in  expressing 
positional  relationships.  Thus  the  word  "syncyst"  refers  to  a  gonic 
cell,  such  as  a  parthenogenetic  ovum,  containing  all  the  elements., 


LOCATIONAL  TEEMS,  CYTOLOGY  OF  DESCENT          127 

factors,  or  determinants  necessary  to  the  production  of  an  individual 
(except,  of  course,  the  environmental  ones),  of  which  the  chromosomes 
are  the  familiar  example,  expressed  in  some  physical  form,  often, 
though  not  necessarily,  of  definite  conformation.  It  is  assumed  that 
these  factors  belong  to  two  classes,  having  opposite,  vital,  chemical, 
or  physical  properties.  By  synecdoche  the  word  syncyst  may  also 
designate  a  gone,  individual  or  species  containing,  or  characterized  by 
syncysts;  similarly  throughout  the  series  of  terms.  In  dicysty  the 
inheritance  mechanism  is  such  that  the  full  complement  of  factors 
necessary  to  the  production  of  an  individual  is  distributed  to  func- 
tional cells  of  two  kinds,  the  macro-("  female")  and  micro-("male") 
gametes,  neither  normally  capable  of  producing  an  individual,  but  which, 
pairing,  form  zygotes  capable  of  producing  an  individual. 

Syncystic.  Of,  or  relating  to,  a  gonic  cell  containing  all  the  factors  necessary 
to  the  production  of  an  individual, — as  in  the  parthenogenetic  ovum.  The 
word  syncystic  may  also  be  applied  to  a  gone,  individual,  or  species  bearing 
syncysts.  Syncysty, — state  of  being  syncystic;  and  so  with  the  following 
five  words. 

Dicystic.  Of,  or  relating  to,  a  gone  bearing  in  separate  cells  the  different  fac- 
tors necessary  for  the  production  of  an  individual;  as  in  syngones.  The 
word  dicystic  may  also  be  applied  to  individuals  and  species. 

Amphicystic.  Of,  or  relating  to,  an  individual  in  which  the  different  groups  of 
factors  necessary  for  the  production  of  a  new  individual  occur  in  separate 
cells  that  are  in  separate  gones;  as  in  many  hermaphrodites. 

Telecystic.  Of,  or  relating  to,  amphicystic  species  in  which  the  different  groups 
of  factors  necessary  for  the  production  of  an  individual  are  borne  in  separate 
cells  in  separate  gones  that  are  in  separate  somas  or  individuals;  as  in  all 
bisexual  forms. 

Homocystic.    Having  or  producing  gonic  cells  all  of  the  same  kind. 

Heterocystic.    Having  or  producing  gonic  cells  of  more  than  one  kind. 

Syncyst.  A  gonic  cell,  or  by  synecdoche,  a  gone,  individual,  or  species,  present- 
ing syncysty. 

Dicyst.    A  gone,  or  by  synecdoche,  an  individual  or  species,  presenting  dicysty. 

Amphicyst.    An  individual  or  species  presenting  amphicysty. 

Telecyst.    A  species  presenting  telecysty. 

Heterocyst.  An  individual  or  species  presenting  both  amphicysty  and  syncysty. 
or  both  dicysty  and  amphicysty,  etc. 

Homocyst.  A  species  presenting  uniformity  in  the  space  relationships  of  its 
different  kinds  of  gonic  intracellular  reproductive  elements. 

Kinetocyst.  A  gonic  cell  whose  elements  are  active,  aggressive,  or  "male."  A 
"male"  gamete;  a  spermatozoon. 

Statocyst.  A  gonic  cell  whose  elements  are  passive,  or  "female."  A  "female" 
gamete;  an  ovum. 


128  NOTES   ON   NEMAS 

Digones,  amphigones  and  heterogones,  and  many  syngones,  are 
dicystic.  The  word  syncysty  and  its  immediate  relatives  may  be 
used  to  designate  the  conditions  present  in  parthenogenetic  organisms, 
in  which  single  gonic  cells  (not  zygotes,  at  least  not  in  the  ordinary 
sense  of  the  word)  contain  all  the  factors  necessary  to  the  production 
of  an  individual.  My  (thus  far  theoretical)  cryptogenetic  organisms 
are  syncysts. 

5 

FUNCTIONS  OF  THE  AMPHIDS 

My  published  observations  emphasize  the  junction  of  each  amphid, 
by  means  of  a  duct,  with  a  chain  of  internal  lateral  organs.  Biitschli 
and  de  Man  each  record  an  instance  of  definite  outflow  from  the  am- 
phids.  I  now  find  this  outflow  in  many  different  genera,  when  speci- 
mens are  fixed  with  Flemming  solution;  from  a  definite  part  of  each 
amphid  there  issues  a  coiled,  or  irregular  "string"  or  "ribbon,"  the  volume 
of  which  precludes  attributing  it  to  an  evagination.  Occasionally  an 
"axis"  is  seen  in  the  "string,"  but  nothing  warrants  the  belief  that 
this  "axis"  is  other  than  a  coagulation  phenomenon,  just  as  it  is  in  the 
similar  coagulation  "strings"  occasionally  seen  at  the  spinneret.  I 
mention  evagination  because  some  investigators  declare  the  amphids 
to  be  supplied  with  special  nerves,  and  because  it  is  conceivable  that 
death  spasms  might  so  act  on  a  nerve  organ  as  to  cause  an  evagination. 
However,  my  numerous  observations  do  not  at  all  support  the  idea 
that  the  appearances  I  have  studied  are  evaginations.  In  many  cases 
I  have  traced  inward  and  backward  from  the  amphids  structures 
whose  histology  in  no  way  suggests  nerve  organs,  but  does  correspond 
in  every  respect  with  the  histology  of  ducts,  especially  those  of  nemas. 

These  new  observations  of  mine  afford,  I  think,  a  better  basis  for 
speculation  as  to  the  function  of  the  amphids,  and  lead  away  from  the 
idea  that  they  are  simply  organs  of  sensation.  I  observe  in  Monon- 
chus,  and  other  genera,  that  invariably  there  is  an  innervated  papilla 
very  close  to  the  amphid.  May  not  confusion  have  arisen  here 
through  different  observers  having  studied  similar-looking,  but  un- 
related structures? 

I  have  instances  of  amphids  so  obscure  that  i£  would  have  been  im- 
possible to  discover  them  had  it  not  been  for  the  issuance  from  them 
during  fixation  of  the  fluid  matter  described. 


THE  MONONCHS1 


(Mononchus  Bastian  1866) 
A  GENUS  OF  FREE-LIVING  PREDATORY  NEMATODES 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  VI 

(With  75  illustrations  in  the  text)2 

BY 

N.  A.  COBB 

INTRODUCTION 

Mononchs  are  Predaceous 

No  free-living  nematodes  have  gained  more  in  interest  during  recent 
years  than  those  constituting  the  genus  Mononchus;  this  is  because  the 
latest  discoveries  have  led  to  a  complete  change  of  view  concerning  their 
economic  relationships.  Careful  examination,  here  recorded,  of  a  large 
number  of  specimens  belonging  to  many  different  species  of  Mononchus, 
has  fully  demonstrated  the  predaceous  character  of  certain  common  and 
widely  spread  soil-inhabiting  species — which  are  found  to  feed  on  other 
small  animal  organisms,  such  as  protozoa  and  rotifers,  and,  most  interest- 

1  Reprinted  from  Soil  Science,  May,  1917,  with  renumbering  of  pages  and  errata,  (p.  184). 

2  For  the  most  part  the  illustrations  were  prepared  under  the  author's  personal  supervision  by 
Mr.  W.  E.  Chambers  of  the  Bureau  of  Plant  Industry.     Many  features  set  forth  in  them  cannot 
be  seen  in  the  natural   object  except  with  the  aid  of  the  best  immersion   lenses  skillfully  used 
under  favorable  conditions.     Frequently  no  further  allusion  is  made  to  facts  thus  elucidated  .  So, 
too,  information  contained  in  the  key  may  not  be  repeated  elsewhere;  the  key  should  therefore  be 
consulted  in  connection  with  each  description.     Most  of  the  illustrations  are  original;  when  not 
so,  their  source  is  indicated.     The  species  figures  are  all  at  the  same  magnification,  so  that  the 
reader  may  judge  of  the  relative  sizes  of  the  nemas.     Explanatory  abbreviations  follow. 


amp — ampulla 
amph — amphid 
an — anus 
an  gl — anal  gland 
ar  dnt — denticula 


cav  som — body  cavity 

cl  int — intestinal  cell 

cl  msc — muscle  cell 

cl   nrv — nerve  cell 

cl  nrv  subm — submedian  nerve 
cell 

col   crd — cardiac  collum 

crd— cardia 

cst  ph — pharyngeal  rib 

cut — cuticle 

dct — duct 

dct  gl  cdl  —  duct  of  one  of  the 
caudal  glands 

dnt — denticules 

fix  ovr  post — flexure  of  poster- 
ior ovary 

gl — gland 

gl  an — anal  gland 

gl  cdl— caudal  gland 

gl  oe — cesophageal  gland 

grn— granule 

gl  sal — salivary  gland 

ing — ingested  material 

ing  nematod  —  ingested  nema- 
tode 

int — intestine 

inc — iunction 

lam   Ib— labial   lamina 


Ib— lips 

lum  int — lumen  of  intestine 

lum  oe — lumen  of  oesophagus 

lum  som — body  cavity 

ms  an — anal  muscle 

msc  oe— cesophageal   muscle 

msc  som — body  muscle 
mur  ex — external  wall 

mur  int — intestinal  wall 

mur  ph — pharyngeal  wall 

mur  ut — wall  of  uterus 

ncl — nucleus 

ncl  cl  int  —  nucleus  of  intesti- 
nal cell 

ncl  lat — lateral  nucleus 

ncl  ov — nucleus  of  ovum 

nrv — nerve 

nrv  r — nerver  ring 

oe — oesophagus 

oes  lum — oesophageal  lumen 

on  dsl — dorsal  tooth    . 

on  rtr  dsl — retrorse  dorsal 
tooth 

on  rtr  subm — retrorse  submed- 
ian tooth 

on  subm  dxt — right  submedian 
tooth 

on   subm   snst — left   submedian 
tooth 

org — orgnn 

ov — ovum 

ov  dct — oviduct 

ov   frt — fertilized   esrg 

(S.  S.431)  129 


ov  im — immature  egg 

p  ex — excretory  pore 

ph  str — pharyngeal  striae 

por — pore 

por  gl  oe — pore  of  oeeophageal 
gland 

ppl — papilla 

ppl  cdl — caudal  papilla 

ppl  intr — interior  papilla 

ppl  Ib — labial  papilla 

ppl   Ib   extr — exterior   labial 
papilla 

ppl   subm — submedian   papilla 

opl  subm  sec  —  secondary  sub- 
median  papilla 

ppl  trm — terminal   papilla 

rcpt   sem — seminal  receptacle 

ret — rectum 

reg  vnt — ventral  field 

set — seta 

spm — spermatozoa 

spn — spinneret 

str   mur   ph — striae   of   pharyn- 
treal  wall 

subcut — subcuticle 

sut  Ib — labial  suture 

teg  ov — egg  shell 

trm  ovr — Wind  en-l  of  ovnrv 

ut — utenis 

vag — vagina 

vagmsc — vaginal   muscle 

vlv — vulva 


J30CS.S.432) 


THE  MONONCHS 


ing  of  all,  on  other  nemas — and  has  made  it  practically  certain  that  all 
mononchs  are  predaceous. 

Economic  Importance.  If,  as  is  often  the  case,  the  nemas  destroyed 
by  the  mononchs  are  nemas  injurious  to  agriculture,  then  the  mononchs 
are  beneficial  to  man.  The  first  definite  instance  of  this  kind  was  reported 
in  the  Journal  of  Agricultural  Research  in  September,  1914 :  Mononchus 
papUlatus  was  shown  to  feed  upon  Tylenchulus  semipenetrans,  the  latter 
a  nema  infesting  the  roots  of  citrus  trees.  Since  that  time  the  writer  has 
observed  many  similar  instances,  fourteen  of  which  are  recorded  herein. 
Formerly  mononchs  were  considered  harmful  to  vegetation.  The 
basis  of  this  opinion  was  twofold:  first,  they  were  known  to  congregate 
about  the  roots  and  between  the  leaf  sheaths  of  plants,  especially  succu- 
lent plants,  in  sufficient  number  to  justify  the  opinion  that  they  would  be 
harmful,  provided  they  were  vegetarians;  second,  vegetable  matter  was 
often  found  in  their  intestines. 

More  careful  investigation,  however,  has  disclosed  other  facts  incom- 
patible with  this  opinion  that  mononchs  are  harmful  to  vegetation.  The 
food-habits  of  mononchs  have  now  been  more  carefully  investigated,  as 
herein  recorded,  and  each  species  so  studied  has  proved  to  be  carnivorous. 
The  presence  of  vegetable  matter  in  a  mononch's  intestine  proves  to  be  no 
very  definite  criterion  of  its  food  habits,  appearances  to  the  contrary  not- 
withstanding. A  deception  has  arisen  that 
is  now  easily  explained.  The  occurrence  of 
vegetable  organisms  in  the  intestine  of  a 
mononch  is  merely  incidental ;  in  many  in- 
stances it  would  be  impossible  for  the  mon- 
onch to  devour  its  prey  without  at  the  same 
time  swallowing  vegetable  matter.  For  in- 
stance, suppose  a  mononch  to  bolt,  as  one 
of  its  victims,  a  monhystera  —  a  common 
occurrence.  Monhysteras  are  vegetarians, 
some  of  them  feeding  almost  exclusively 
upon  diatoms,  others  upon  other  kinds  of 
unicellular  algae.  Both  on  account  of  their 
peculiar  structure  and  their  bright  green 
color,  these  diatoms  and  other  algae  are  very 
conspicuous  objects  in  the  intestine  of  the 
monhystera.  Imagine  now  the  appearances 
presented  by  the  body  of  an  ingested  mon- 
hystera, swallowed  whole,  or  nearly  so,  and 
lying  lengthwise  in  the  intestine  of  a  mononch.  Under  such  circum- 
stances, which  are  entirely  normal,  the  diatoms  and  other  algae  in  the 
intestine  of  the  monhystera  may  be  observed  through  the  colorless  tissues 


FIG.  1 
A  mononch 
about  to  seize 
its  victim. 
The  head  is 
drawn  from 
nature  and 
is  exact  in 
every  detail. 
The  body  is 
more  or  less 
posed.  The 
strong  teeth 
and  rasp-like 
organs  in  the 
mouth  are 
well  shown. 


FOOD  HABITS  (S.S.433)j3i 

of  both  the  mononch  and  the  monhystera,  without  the  body  wall  of  either 
nema  being  very  plainly  visible :  it  is  somewhat  as  if  one  looked  through 
the  walls  of  two  glass  tubes,  one  within  the  other,  to  view  comparatively 
conspicuous  objects  in  the  inner  tube.  Such  an  observation  might  easily 
lead  to  the  conclusion  that  the  mononch  had  been  feeding  upon  unicellular 
algse.  The  deception  is  heightened  after  the  body  of  the  monhystera  is 
partially  digested,  for  then  all  vestiges  of  the  monhystera  become  practi- 
cally invisible,  and  there  are  left  as  comparatively  conspicuous  remains 
the  less  readily  digested  vegetable  matter,  lying  loose  in  the  intestine  of 
the  mononch, — the  frustules  of  diatoms  for  instance,  which  of  course 
are  wholly  indigestible.  Taking  everything  into  consideration,  it  is  not 
in  the  least  surprising  that  hitherto  observers  have  been  deceived  as  to 
the  food  habits  of  mononchs. 

As  nematologists  heretofore  have  not  carefully  studied  the  food  habits 
of  mononchs,  particular  attention  was  given  them  in  the  course  of  these 
investigations ;  but  in  spite  of  the  care  exercised  much  remains  to  be  dis- 
covered. The  mouth  parts  and  digestive  organs  have  come  in  for  special 
study,  since  it  is  mainly  here  that  we  get  clues,  faint  and  puzzling  though 
they  be,  that  help  interpret  the  little  we  can  glimpse  of  the  food  habits  of 
these  organisms  in  their  natural  state.  Soil  mononchs  live  in  darkness 
and,  as  might  be  expected,  behave  in  a  wholly  unnatural  way  when  placed 
in  water  on  a  microscope  slide  and  brought  in  a  drowning  condition 
into  the  blaze  of  light  necessary  to  a  microscopic  examination.  The  dif- 
ficulties and  delays  attendant  on  such  a  line  of  research  are  manifest. 
Nevertheless,  certain  fundamental  facts  have  been  established;  new  or- 
gans have  been  discovered  and  light  has  been  thrown  on  the  true  nature 
and  function  of  organs  not  hitherto  understood.  It  has  seemed  best  to 
dwell  on  the  various  habits  and  functions  while  describing  the  structures 
with  which  they  are  associated. 

As  we  gain  familiarity  with  the  food  habits  of  nemas,  it  becomes  pos- 
sible on  this  new  basis  to  make  comparative  anatomical  studies,  the  results 
of  which  may  be  applied  in  determining  the  food  habits  of  newly  discov- 
ered genera  and  species. 

I 
STRUCTURE,  FUNCTIONS,  AND  DISTRIBUTION  OF  MONONCHS 

The  mononchs  constitute  a  genus  of  free-living,  predatory  nematodes 
inhabiting  soil  and  fresh  water,  as  well  as  the  above-ground  parts  of  cer- 
tain plants.  The  average  form  and  size  of  a  mononch  is  indicated  by  the 

2.2     7.4     25.     '63>2S     92.7 

following  average  formula: —  2-4  mm-* 

2.1     2.6       3.        3.2      2. 

*  This   formula,   which   is   now   coming  into   more  general   use,   is  simply   a   decimal   method   of 
stating  concisely  the  necessary  measurements.     The   formula  is   fully  explained  in  the  appendix, 

r.  184. 


132(S-S.434) 


THE   MONONCHS 


which   corresponds   very  closel} 


with  that  of  the  type  species  of  the 
genus,  M.  truncatus  Bastian,  and  espec- 
ially with  M.  papillatus  Bastian. 

Skin  or  Cuticle 

Strics.  While  the  skin  of  these  nemas 
usually  described  as  smooth  and 
without  striations,  yet  minute  trans- 
verse striae  are  probably  always  present, 
though  difficult  of  resolution  except  in 
the  new  species  reversus  and  similis. 
Using  a  good  objective  of  the  highest 
power  under  favorable  conditions,  I 
have  almost  invariably  been  able  to  see 
these  striae,  and  as  my  examinations 
have  embraced  the  great  majority  of 
the  known  species,  it  seems  probable 
that  any  specimen  will  reveal  them  if 
examined  with  sufficient  care.  These 
transverse  striae,  all  alike  on  a  given 
specimen,  are  never  sufficiently  marked 

,  ,  FIG.  2.  —  Female 
of  a  typical  mononch, 

par  Mononchus  longi- 
,  caudatus,  a  syngonic 
form.  This  individ- 
ual  had  been  feast- 
ing on  other  nemas, 
t  h  e  remains  of 
which  are  shown  in- 
side the  intestine. 
Only  the  anterior 
half  of  the  sexual 
organs  can  be  seen 
in  the  illustration; 
an  entirely  similar 
branch  is  hidden  on 
account  of  the  coiled 
attitude  of  the  body. 
The  lettering  of 
the  illustrations  is 
similar  throughout 
and  is  explained  at 
the  bottom  of  page 
129.  The  anatomy 
and  histology  o  f 
various  newly  dis- 
covered features  are 
shown: — 

GJsophageal  glands 
(gl.    sal.),    the    pore 
mlr  Inf  through     which     the 
glands     empty     into 

-.  theossophagus  (par.), 
syngonic  sperm 

j,     (spm.),  formation  of 

""  polar  body  (ov.frt.), 
ingested  protozoon 
(ing.),  etc. 


to  disturb  the  plain,  even  contour  of  the  body.     It  is  rarely  possible  to 


CUTICLE  AND  MOULTING  (8.8.435)133 

resolve  the  striae  into  components ;  occasionally,  however,  they  are  resolv- 
able into  rows  of  excessively  fine  dot-like  elements,  as  for  instance  in 
bathybius,  reversus  and  incurvus.  Lateral  wings  to  the  cuticle  are  almost 
unknown,  and  the  striae  are  not  perceptibly  altered  on  the  lateral  fields; 
papillatus  and  macrostoma  furnish  a  slight  exception  to  this  rule. 

Though  the  muscles  of  the  body  wall  are  relatively  powerful,  their 
attachments  to  the  subcuticle  are  not  a  conspicuous  feature ;  hence  longi- 
tudinal striae  due  to  this  cause,  though  of  rather  common  occurrence,  are 
not  very  readily  observed.  There  are  no  longitudinal  striations  in  the 
cuticle  proper.  This  apparent  complete  absence  of  dermal  markings  often 
imparts  a  glassy  appearance  to  living  mononchs  when  examined  casually 
under  the  microscope,  an  effect  that  is  heightened  by  the  fact  that  the 
colorless  body  wall  is,  as  a  rule,  of  more  than  average  thickness.  Despite 
their  rather  thick  cuticle,  mononchs  are  very  flexible.  They  coil  and  un- 
coil themselves  with  facility, — a  useful  gift  in  a  struggle  with  active  prey. 
Moulting.  From  researches  on  a  considerable  variety  of  genera,  Mau- 
pas  concluded  that  nematodes  undergo  four  moults,  and  that,  correspond- 
ingly, the  life  of  each  individual  is  divided  into  five  periods.  He  exam- 
ined no  mononchs.  The  accompanying  sketch  of  a  portion 
of  the  pharynx  of  a  moulting  Monochus  brachyuris,  from 
Arlington,  is  therefore  of  interest,  as  indicating  that  this 
specimen  had  yet  to  moult  three  times ;  and  since  it  was 
already  half-grown  (0.8  mm.  long)  it  is  fair  to  presume  it 
had  already  moulted  once,  although  of  course  there  is  no 
proof  of  this.  The  sketch  shows  four  successive  dorsal 
onchi,  numbered  in  chronological  order,  each  the  represent- 
ative  of  a  separate  cuticle.  The  fourth  onchus  is  in  a  very  lessive 'dorsal 
rudimentary  state.  This  record  accords  with  the  observa-  :eth>  *' 2>  3' 4' 
tions  of  Maupas,  and  indicates  the  probability  that  mononchs  also  moult 
four  times. 

Strength  and  Activity.  Various  features  of  the  cuticle  and  body- 
muscles  seem  to  stamp  the  mononchs  as  powerful  nemas,  and  when  they 
are  taken  from  their  natural  haunts  and  placed  in  a  glass  of  water  for 
examination,  their  active  serpentine  movements  fully  justify  the  infer- 
ence. Though  less  agile  than  species  belonging  to  some  other  genera, 
they  are  anything  but  sluggish.  The  movements  of  the  anterior  extremity 
are  especially  striking,  a  certain  suppleness  of  neck  enabling  them  to 
dart  the  head  suddenly  here  or  there  in  almost  any  direction, — a  faculty 
enabling  them  with  ease  to  capture  their  prey,  even  though  it  be  active. 

Nemas  Sometimes  Float 

Distribution  by  flotation.  Ditlevsen  notes  a  very  interesting  trait  of 
his  Mononchus  spectabilis,  namely,  that  of  floating  on  the  surface  of 
water.  A  number  of  free-living  nemas  belonging  to  other  genera  are 


134(3.3.436)  THE  MONONCHS 

known  to  have  this  faculty,  which  is  due  to  repulsion  between  the  cuticle 
and  water  ;  de  Man  found  it  to  exist  in  the  case  of  Oncholaimus  viscosus, 
and  the  writer  has  observed  it  in  the  case  of  the  larvse  of  Diplogaster 
aerivora,  although  a  second  larval  form  of  this  same  species  does  not 
exhibit  the  property,  nor  do  the  adults.  Ability  to  float  is  known  also  of 
a  number  of  other  species,  and,  as  Ditlevsen's  observations  show,  is  not 
absent  in  the  genus  Mononchus.  Whether  flotation  plays  any  part  in  the 
economy  of  such  nemas  is  not  known  with  certainty.  Floating  on  the 
surface  of  moving  water,  nemas  would  doubtless  sometimes  be  quickly 
and  widely  distributed,  and  it  is  therefore  easily  conceivable  that  flotation 
has  some  definite  bearing  on  the  life  history  of  species  exhibiting  it. 

The  surface  of  a  mononch  seems  almost 

*'Jfc'  —  >^^-^H—  -^T^  '  entirely  destitute  of  setae  and  papillae,  if 

we  except  those  on  the  lips.  Neverthe- 
less, future  researches  will  probably  re- 
veal superficial  nerve-endings  hitherto 
overlooked.  In  rare  instances  a  few  fairly 
well-developed  setae  occur  on  the  tail,  as 
in  the  case  of  M.  sigmaturus;  papillae  also 
occur  sparingly  on  the  tails  of  the  males 
of  various  species,  and  near  the  vulva  on 
the  females  of  a  number  of  species.  No 

the  lips  are  nearly  closed,  but  the  dor-       pores    are    known    tO   OCCUr    in    the    CUticle, 

Si",  Sr£~'£SS     except,  of  course,  the  spinneret  pore,  and 

of  papilla:  are  seen  to  good  advantage,     the  pore  observed  near  the  nerve-ring  and 

to  be  the  renette  pore. 


General  Form  of  Body 

Neck  and  Head.  The  various  mononchs  are  considerably  alike  in 
external  form.  In  front  the  body  tapers  but  little;  the  neck  is  nearly 
always  more  or  less  cylindroid,  and  almost  invariably  ends  in  a  head  not 
set  off  from  the  neck  in  any  way,  though  there  is  usually  a  slight  expan- 
sion at  the  lip-region,  due  to  the  strong  development  of  the  labial  papillae. 

Tail  and  Spinneret.  The  posterior  portion  of  the  body  usually  tapers 
from  some  distance  in  front  of  the  anus,  but  in  the  pre-anal  region  the 
diminution  is  slight  and  very  gradual.  The  tail  may  be  either  simply 
conoid,  or  first  conoid  and  then  cylindroid,  and  usually  ends  in  a  spin- 
neret, though  in  about  one-fourth  of  the  species  the  caudal  glands  and 
spinneret  are  absent.  When  the  tail  is  conoid  the  spinneret  is  usually  a 
simple  structure,  whose  existence  is  indicated  mainly  by  the  fact  that  the 
terminus  is  sub-truncate  in  form,  and  presents  an  inconspicuous  axial, 
or  sub-dorsal,  or  sub-ventral  pore.  This  form  of  spinneret  appears  to  be 
entirely  unarmed,  though  inconspicuous  innervations  probably  occur. 


LABIAL  APPENDAGES  (S.  S.  437)  135 

When  the  posterior  portion  of  the  tail  is  cylindroid,  the  terminus  is 
usually  almost  imperceptibly  expanded,  and  the  spinneret  is  then  some- 
what differently  developed,  and  is  usually  armed 
with  obscure,  innervated,  submedian  papillae  or 
setae. 

Head 


Lips.     In  the  view  usually  obtained  the  six  lips 
appear  to  be  more  or  less  confluent,  and  if  it  were 
not  for  their  papillae  it  would  be  difficult  to  count 
them  ;  but  when  thrown  apart,  an  attitude  in  which,      x  1000 
however,  they  are  seldom  seen,  they  are  more  easily        ,, 

J  J  J  ric.    5*  —  opinncret    ox 


counted,  since  in  this  attitude  the  refractive  "cerat-  ££  '"Ss^whos*'  contrac- 
inous"  internal  elements  of  the  lips  are  separated  Jon  ^openswth°ese  spinneret 
from  each  other  and  more  readily  distinguishable,  as  shown  in  figure  1. 
When  closed,  these  six,  broad,  flat  lips  meet  together  in  such  a  way  that 
the  star-shaped  mouth  opening  usually  lies  in  a  slightly  depressed  area  on 
the  middle  of  the  front  of  the  head.  In  some  species  the  inner  walls  of 
the  lips  are  strongly  "ceratinized,"  and  may  be  developed  into  six  rather 
definite,  retrorse,  subacute  points,  which,  in  assaults  on  other  animals, 
serve  as  grappling  hooks,  and  act  in  opposition  to  the  dorsal  tooth  of  the 
pharynx. 

Labial  papilla.  Each  lip  is  supplied  with  at  least  two,  usually  more  or 
less  conical,  innervated  papillae;  one  on  the  outer  margin  and  somewhat 
outward  pointing,  the  other  situated  about  half  way  between  the  outer 
papilla  and  the  centre  of  the  head,  and  forward-pointing.  The  front  of 
the  head  therefore  presents  two  circlets  of  papillae,  one  on  its  outer  mar- 
gin, and  one  more  closely  surrounding  the  mouth-opening,  as  shown  in 
figures  1  and  4,  and  many  others.  These  papillae  may  be  so  flat  as  to 
play  no  conspicuous  part  in  the  external  conformation  of  the  head,  or 
they  may  be  conical  and  raised,  so  as  to  give  to  the  front  of  the  head  a 
more  or  less  angular  contour.  The  papillae  are  slightly  mobile,  and  hence 
vary  somewhat  in  appearance  at  different  times  on  the  same  specimen,  a 
matter  depending  on  the  attitude  of  the  lips.  Drowned  specimens  with 
relaxed  lips  present  a  slightly  different  appearance  from  those  that  have 
been  fixed  for  examination  by  means  of  chemicals. 

Some  of  the  innervations  that  frequently  occur  on  the  head  near  the 
lips  may  have  special  functions.  Structurally  they  are  sometimes  indis- 
tinguishable from  the  subordinate  labial  papillae.  The  species  figures 
show  the  location  of  some  of  these  innervations.  One  pair  of  them  is 
very  near  the  amphids  —  the  only  nerves  so  far  observed  to  be  definitely 
associated  with  the  amphids.  These  particular  papillae  are  so  uniform  in 
their'  occurrence  that  it  seems  likely  they  have  a  special  function,  con- 
nected with  the  use  of  the  amphids. 


136<S.S.438)  THE   MONONCHS 

I 

Mononchus:  Number  of  Labial  Papillae  in  the  Outer  Set 


14 

10 

6 

'  Doubtful: 

said  to  be  6 

acutus 

bathybius 

muscorum  var. 

brachyttris 

dadayi 

obtusicaudatus 

macrolaimus 

brachylaimus 

brevicaudatus 

obliauus 

lacustris 

digiturus 

parvus 

dentatus 

consimilis 

radiatus 

megalaimus 

dolichurus 

punctatus 

gracilicaudatus 

denticulatus 

reversus 

minor 

exilis 

ex 

major 

gerlachei 

sigmaturus 

palustris 

fovearum 

pectabilis 

monhystera 

incurvis 

subsimilis 

sparsus 

gymnolaimus 

tuderi 

muscorum 

longicaudatus 

angustus 

teres 

index 

enuicaudatus 

papillatus 

longicollis 

trichurus 

tunbridgensis 

intermedius 

ridentatus 

rapax 

micrurus 

vorax 

japonicus 

runcatus 

regius 

macrostoma 

schokkei 

Comparative  morphology  of  the  cephalic  papilla.  The  outer  set  of 
cephalic  papillae  is  the  morphological  equivalent  of  the  circlet  of  cephalic 
setae  often  to  be  seen  on  other  free-living  nemas.  In  harmony  with  this 
fact,  the  submedian  papillae  of  this  outer  set  are  sometimes  two  or  three 
in  number  to  each  lip,  the  numerical  and  morphological  factors  harmoniz- 
ing with  the  law  of  arrangement  of  the  tactile  cephalic  setae  of  nemas, 
namely: — when  six  are  present  one  is  found  on  each  of  the  two  lateral 
lines  and  one  on  each  of  the  four  submedian  lines ;  when  more  than  six 
are  present  the  increase  occurs  first  on  the  submedian  lines,  the  common- 
est number  being  ten, — one  on  each  lateral  line  and  two  on  each  of  the 
four  submedian  lines;  when  the  number  is  in  excess  of  ten  the  increase 
is  again  more  commonly  found  on  the  submedian  lines.  Illustrations  of 
this  law  of  arrangement  are  seen  on  the  heads  of  many  mononchs.  The 
secondary  submedian  papillae  of  mononchs  are  sometimes  minute  and 
more  or  less  difficult  to  detect. 

Method  of  Hunting 

Senses  of  Smell  and  Taste.  Obviously  mononchs  hunt  by  the  aid  of 
some  other  sense  than  that  of  sight,  since  both  they  and  their  prey  usually 
live  in  subterranean  darkness.  It  is,  therefore,  exceedingly  likely  that 
the  nerve  endings  on  the  head,  terminating  in  the  labial  papillae  of  the 
inner  row,  serve  as  organs  of  taste  and  smell,  and  that  it  is  by  the  aid  of 
these  senses  that  they  trail  their  quarry. 

Picture  these  ferocious  little  mononchs  engaged  in  a  ruthless  chase  in 
the  midst  of  stygian  darkness.  We  may  imagine  them  taking  up  the 
scent  of  the  various  small  animals  upon  which  they  feed,  among  which 
almost  anything  they  can  lay  mouth  to  seems  not  to  come  amiss,  and 
pursuing  them  with  a  relentless  zeal  that  knows  no  limit  but  repletion. 
How  many  acres  have  their  organic  balance  determined  by  their  millions 
of  prowling  mononchs  ? 


PHARYNX 


(S.  5.439)137 


Pharynx 

The  six  powerful  lips  arch  together  over  a  large  characteristic 
pharynx,  consisting  of  a  rather  simple,  ellipsoidal  or  elongated  cavity, 
whose  cross-section  is  more  or  less  irregularly  circular,  and  of  which 
there  are  two  distinct  types. 

Types  of  Maw.  Teeth.  In  one  type,  characteristic  of  the  larger 
species,  there  are  longitudinal  ribs,  sometimes  simple,  sometimes  duplex, 
situated  mainly  on  the  median  and  submedian 
lines  (subgenus  lotonchus).3  When  these  lon- 
gitudinal ribs  are  well-developed  there  is  a 
tendency  for  the  dorsal  tooth  or  onchus  to  be 
farther  back,  and  for  the  submedian  teeth, 
smaller  still,  to  be  located  toward  the  base  of 
the  pharynx,  and  in  extreme  cases  all  three 
teeth  may  be  located  actually  at  the  base  of 
the  pharynx,  or  indeed  be  quite  vestigial.  The 
farther  back  the  teeth,  the  smaller  they  are, 
and  when  located  actually  at  the  base  of  the 
pharynx  they  are  often  exceedingly  small. 

In  the  other  type  of  pharynx   the  dorsal 
tooth   is   usually   strongly    devel- 
^pk,      M    oped,  and  is  located  midway  or 
fj         H    farther   forward ;   in  which   case 


X750 


FIG.  6. — Dorsal  view  of  the 
throat  of  M.  muscorum,  to 
show  the  arrangement  of  den- 
ticles (dnt.)  characteristic,  of 
the  subgenus  Prionchulus;2  they 
constitute  a  rude  "saw."  Com- 
pare with  Fig.  7. 


o 


the  wall  of  the  pharynx  is  strongly  reinforced  along  the  dor- 
sal line,  while  the  submedian  longitudinal  ribs  are  lacking, 
or  at  any  rate  are  faint.  However,  there  often  occurs  on 
each  of  the  two  ventrally  submedian  lines  in  this  type  of 
pharynx  an  onchus  of  smaller  size,  located  a 

0  little  farther  back  than  the  main  onchus ;  ex- 
ceptionally these  submedian  onchi  may  be 
nearly  as  large  as  the  dorsal  onchus.  In 
several  species  the  onchi  are  retrorse  (sub- 
genus  Anatonchus5} ,  and  when  of  this  char- 
acter are  sometimes  more  slender,  even  some- 
what digitate. 

Fangs.  Denticles.  The  onchi  act  as  fangs, 
and  are  used  in  conjunction  with  the  power- 
ful lips  in  seizing  and  holding  the  prey.  In 
these  maneuvers  they  are  aided  by  minor 
pharyngeal  structures,  prominent  among 
which  in  some  species  are  two  submedian 

'lotonchus,   insignificant  tooth;    4  Prionchuhis.   a   small   saw-tooth;    B  Anatonchus,  reversed    tooth. 


FIG.  7. — Above,  profile  and  front 
view  of  the  same  series  of  denticles 
in  the  throat  of  M.  muscorum.  Be- 
low, two  cross-sections  of  the  same 
specimen,  showing  end  view  of  the 
same  denticles;  at  left  the  section 
is  through  the  dorsal  tooth  (shown 
black) ;  at  right  the  section  is  above 
the  tooth.  The  denticles  are  shown 
in  the  upper  part  of  these  two  lower 
figures.  The  two  joints  shown  in  cross- 
section  impart  a  slight  degree  of 
mobility  to  the  pharyngeal  walls. 
Compare  with  Fig.  6. 


138(s-s-440)  THE  MONONCHS 

areas,  armed  with  minute  denticles  arranged  in  transverse  rows  like  the 
teeth  of  a  rasp  (subgenus  Mylonchulus6).  While  these  denticles  are 
usually  distributed  in  two  distinct  areas,  the  two  sometimes  coalesce  on 
the  ventral  line,  so  that  the  denticulated  area,  or  rasp,  is  continuous  and 
bilaterally  symmetrical.  As  a  rule,  however,  there  is  a  distinct,  narrow, 
ventral  interruption,  so  that  the  right  and  left  rasps  are  rather  clearly 
separated  from  each  other.  These  rasps  are  widest  near  the  ventral  line, 
and  become  gradually  narrower  as  they  recede,  and  usually  end  near  the 
lateral  line,  or  near  the  dor  sally  submedian  line.  On  the  margins  of  the 
rasps  the  denticles  are  arranged  in  distinct  rows ;  elsewhere  the  arrange- 
ment is  more  or  less  irregular,  though  in  certain  species  the  arrangement 
is  rather  orderly  throughout.  Each  rasp  is  composed  of  about  six  rows 
of  denticles,  except  in  the  species  denticulatus,  where  the  number  of  rows 
is  about  twice  (?)  as  great,  and  in  the  new  species  sparsus  and  reversus, 
where  there  are  only  one  or  two  rows.  Often  at  the  base  of  each  rasp 
there  is  an  exceedingly  minute  submedian  onchus. 

Method  of  Attack.  When  used  in  conjunction  with  the  strong  dorsal 
tooth  and  the  powerful  lips,  the  rasps  are  remarkably  efficient  organs. 
The  mononch  glides  up  to  its  quarry  and  makes  its  onslaught  by  a  quick 
snap  of  the  head,  throwing  its  jaws  suddenly  wide  open,  and  grappling 
its  prey  by  means  of  the  inner  armature  of  the  lips.  As  the  jaws  close  in, 
the  victim's  body  is  jammed  against  the  point  of  the  dorsal  tooth,  as  well 
as  against  the  rasps,  and  in  this  way  is  at  once  both  punctured  by  the  tooth 
and  lacerated  or  milled  by  the  rasps.  In  most  cases  the  onchi  seem  to  be 
solid  bodies,  containing  no  duct  through  which  venom  could  empty.  If 
any  poison  is  injected  into  the  victim  it  would  seem  to  be  derived  from 
cesophageal  glands  emptying  into  the  pharynx  by  some  other  road.  The 
axial  element  sometimes  seen  in  the  onchus  is  probably  a  nerve  ending. 

Minutia  of  the  Wall  of  the  Throat.  In  general  the  wall  of  the  pharynx 
is  well  developed  and  strongly  refractive,  and  is  usually  thickest  on  the 
dorsal  side  where  it  gives  support  to  the  dorsal  onchus ;  often  it  is  very 
finely  transversely  striated.  In  many  species  this  striated  appearance 
seems  to  be  due  to  a  transverse  lamination  of  the  pharyngeal  wall.  The 
striation,  or  lamination,  may  be  so  pronounced  as  to  give  rise  to  transverse 
ridges  on  the  interior  surface  of  the  pharynx  like  those  of  the  teeth  of  a 
mill-saw  file,  and  no  doubt  these  ridges  have  somewhat  the  same  function 
as  the  rasps  just  described.  The  onchi  are  sometimes  seen  to  be  longi- 
tudinally striated.  The  striae  of  the  pharyngeal  walls  are  most  clearly  visi- 
ble during  the  moulting  period.  In  the  original  species-figures  to  follow, 
•what  appears  merely  as  shading  on  the  pharyngeal  wall  is  a  carefully 
worked-out  chart  of  the  position,  number  and  direction  of  these  lami- 
nations. 

8  Mylonchulus,   a   small   mill-tooth. 


PHARYNX 


(s.  s.  441)  139 


Contour  of  the  Maw.  The  contour  of  the  pharynx  differs  somewhat 
in  the  various  species.  If  the  dorsal  onchus  is  strongly  developed,  the 
profile  indicates  a  roughly  goblet-shaped  or  ellipsoidal  cavity,  and  the 
onchus  extends  well  into  the  cavity  so  that  its  apex  lies  near  the  axis  of 
the  head,  sometimes  up  front  and  close  to  the  inner  margins  of  the  lips. 
If,  on  the  other  hand,  the  dorsal  onchus  is  weak;  and  especially  in  species 

FlG-  8.  —  Female  of  M.  papillatus,  a  common  cosmopoli- 
tan soil-inhabiting  beneficial  species,  known  to  feed  upon 
plant-infesting  nematodes.  The  cesophageal  glands  (gl. 
oe.)  are  well  developed  in  this  mononch;  they  empty  into 
the  oesophagus  and  no  doubt  "lubricate"  it  during  the  act 
of  swallowing.  This  mononch  is  also  syngonic.  Sperm  of 
female  origin  is  shown  in  the  uterus  at  spm.  For  expla- 
nation of  lettering  see  page  129. 


M 
mrit 

dec 
ad  dot 


where  the  wall  is  not  much  reinforced  by  longitudinal  ribs,  the  contour  of 
the  pharynx  tends  to  be  more  or  less  oblong,  so  that  its  floor,  lying  in  the 
anterior  end  of  the  oesophagus,  though  irregular,  is  likely  to  be,  on  the 
whole,  more  nearly  flat.  Opposite  the  dorsal  onchus  there  is  frequently 
to  be  seen  a  faint  transverse  seam,  most  prominent  along  the  ventral  side 


THE  MONONCHS 


of  the  pharynx,  indicating  a  division  of  the  wall  into  anterior  and  posterior 
elements.  Sometimes  this  pharyngeal  suture  is  rather  prominent. 

Jaw  Muscles.  The  pharyngeal  muscles  of  various  species  of  mononchs 
have  been  observed,  figured  and  commented  upon  by  one  or  two  investi- 
gators, but  only  in  a  vague  way.  Much  remains  to  be  learned  concerning 
them.  The  following  incomplete  observations  have  been  made  in  the 
course  of  these  investigations. 

Under  suitable  conditions,  and  especially  in  some  species,  long,  slen- 
der muscles  may  be  seen  passing  from  the  lip  region  backward  and  out- 
ward, so  that  their  proximal  attachment  is  to  the  body-wall  a  short 
distance  behind  the  pharynx.  These  muscles  are  the  flexor  muscles  of 


X750 


FIG.  9.  —  Side  view  of 
the  head  of  M.  regius. 
The  lips  and  their  ap- 
pendages are  well  shown. 
The  flaps  (lam.  Ib.)  are 
the  same  organs  so  well 
seen  in  figure  4.  The 
amphid  (amph.)  extends 
to  the  bottom  of  the 
pharynx  and  beyond.  The 
labial  muscles  (msc.)  are 
so  attached  as  to  pull  the 
lips  both  inward  and  out- 
ward about  the  stiff  exter- 
nal ring  as  a  fulcrum. 
Traces  of  this  ring  are 

margin  of  the  anterior 
part  of  the  head.  Com- 
ing up  from  the  interior 
of  the  oesophagus  toward 
the  right  is  seen  a  light- 
colored  duct;  this  empties 
into  the  pharynx  at  its 
base.  In  this  way  appar- 
ently the  secretion  of  the 
oesophageal  glands  has  a 
direct  passage  to  the 
throat 


the  lips.  It  is  certain  that  each  lip,  probably  each  pair  of  adjacent  lips,  is 
connected  with  a  muscle  whose  function  is  to  pull  the  lip  toward  the  body 
axis  about  a  fulcrum  near  the  surface  of  the  head.  These  muscles,  then, 
shut  the  mouth.  It  seems  likely  that  the  elasticity  of  the  various  parts 
composing  the  frame-work  of  the  lips  and  pharynx  may  play  some  part 
in  mastication  and  deglutition,  and  act  in  opposition  to  some  of  the  mus- 
cular elements  of  the  pharynx.  The  extent  to  which  a  mononch  can 
throw  its  jaws  open  is  shown  in  the  sketch,  figure  1,  made  from  a  pre- 
served specimen.  This  act  is  accomplished  by  the  aid  of  a  second  similar 
set  of  muscles  acting  on  the  outside  of  the  same  fulcra.  It  is  unlikely 


DEGLUTITION  (S.  s.  443)  141 

that  the  sketch  represents  the  maximum  gape,  for  the  effect  of  chemical 
fixatives  seems  to  be  to  lock  the  jaws  tightly  rather  than  leave  them  agape. 
When  examined  alive  mononchs  are  seldom  seen  to  move  their  mouth 
parts. 

The  Mononch  and  Its  Victim 

Fate  of  Victim.  So  far  as  I  am  aware,  the  struggle  of  a  mononch 
with  its  victim  has  never  been  witnessed  by  human  eyes.  A  struggle  it 
must  be,  for  mononchs  are  sometimes  discovered  that  have  gulped  down 
other  nemas  nearly  half  as  long  as  themselves.  Such  a  denoument  must 
be  the  result  of  a  dramatic  conflict.  A  similar  gastronomic  exploit  on 
the  part  of  a  man  would  be  the  gulping  down  of  a  string  of  bologna  sau- 
sage several  feet  in  length.  In  one  instance  in  the  course  of  my  experi- 
ence, a  mononch  was  caught  with  its  quarry,  another  nematode,  still 
gripped  in  its  jaws.  Seized  by  its  middle,  the  victim  had  been  bitten 
nearly  in  two.  This  is  a  common  fate.  Sometimes,  however,  the  ingested 
nema  is  but  little  mangled.  I  imagine  the  mononch  swallows  its  prey 
somewhat  as  the  python  does,  though  less  deliberately.  As  the  oesophagus 
seldom  occupies  over  one-fourth  of  the  length  of  the  body,  and  as  the 
mononch  sometimes  swallows  other  nemas  nearly  half  as  long  as  itself, 
manifestly  in  such  cases  one  end  of  the  victim's  body  must  reach  the 
mononch's  stomach  before  the  other  end  has  disappeared  down  its 
throat. 

Gluttonous  Appetite.  While  many  mononchs  bolt  their  food,  it  is 
evident  that  the  food  of  some  among  them  receives 
a  certain  amount  of  mastication,  for  the  body  of 
the  victim  is  bitten  into  fragments  and  swallowed 
piece-meal.  In  some  cases  the  degree  of  mastica- 
tion may  be  greater  still.  Figure  10,  for  instance, 
shows  the  head  of  a  preserved  specimen,  in  the 
mouth  of  which  lies  a  portion  of  the  "gizzard"  of  a 
rotifer,  which  has  been  almost  completely  denuded 
of  the  muscular  tissue  originally  attached  to  it.  It 
is  the  thick-lipped  species  like  M.  muscorum  that 
masticate  their  food  in  this  way. 

(Esophagus  or  Gullet 

Lining  of  the  Gullet.  Salivary  (?)  Glands.  The  oesophagus  is  more 
or  less  cylit?droid,  a  form  of  oesophagus  common  in  nemas  that  engorge 
relatively  large  objects.  The  anterior  end  of  the  oesophagus,  where  it 
receives  the  base  of  the  pharynx,  is  usually  about  one-half  to  two-thirds  as 
wide  as  the  base  of  the  head,  and  is  occasionally  somewhat  swollen,  so 
that  one  may  speak  with  propriety  of  an  obscure  pharyngeal  bulb.  The 
oesophagus  has  nearly  the  same  diameter  throughout  the  greater  portion  of 


142(S-S.444)  THE  MONONCHS 

its  length ;  it  may  diminish  a  trifle  in  the  vicinity  of  the  nerve-ring,  while 
in  the  posterior  half  it  usually  expands  a  trifle,  so  that  finally  it  is  one- 
half  to  two-thirds  as  wide  as  the  corresponding  portion  of  the  body.  The 
refractive  lining  of  the  oesophagus  is  strongly  developed,  and  is  of  such  a 
character  that  its  longitudinal  optical  section  often  occupies  as  much  as 
one-third  of  the  diameter  of  the  whole  organ,  sometimes  one-half,  excep- 
tionally even  more.  The  radial  musculature  of  the  oesophagus  is  strongly 
developed,  and  usually  appears  coarser  posteriorly  than  anteriorly. 

(Esophageal  Glands.  In  some  species,  very  likely  in  all,  among  the 
interstices  of  the  cesophageal  muscles  there  exist  glandular  tissues,  which 
empty  their  secretion  into  the  lumen  of  the  oesophagus  through  minute 
pores  in  the  lining,  situated  from  place  to  place  throughout  a  considerable 
portion  of  the  length  of  the  organ.  Some  of  these  glands  appear  to 
empty  into  the  pharynx,  but  the  best  developed  ones  occur  in  the  dorsal 
section  of  the  oesophagus  near  the  middle. 

De  Man  and  Micoletzky  mention  structures  in  the  wall  of  the  pharynx 
of  Mononchus,  about  the  nature  of  which  they  seem  doubtful,  but  sug- 
gest the  possibility  that  they  are  pores.  My  observations  lead  me  to  the 
conclusion  that  some  of  the  more  minute  so-called  "teeth"  or  denticles 
of  authors,  at  the  bottom  of  the  pharynx,  and  even  some  of  those  higher 
up,  are  in  reality  elevated  pores  connected  with  glandular  structures  in 
the  anterior  part  of  the  oesophagus.  These  pores  appear  to  me  to  be  the 
homologues  of  the  pores  which  I  have  demonstrated  undoubtedly  to 
exist  farther  back  in  the  oesophagus,  and  to  be  the  outlets  of  glands 
located  in  the  interstices  of  the  radial  muscles.  See  fig.  9. 

It  is  easy  to  believe  that  the  cesophageal  glands  are  salivary  glands,  and 
that  they  serve  the  mononchs  in  gorging  down  food  in  somewhat  the 
same  way  as  do  the  glands  of  serpents.  This  surmise 
is  based  upon  the  structure  and  position  of  the 
organs  rather  than  upon  definite  and  extensive  physio- 
logical experiment;  intra  vitam  stains,  however,  have 
shown  that  the  secretions  of  these  glands  are  alkaline, — 
evidence  supporting  the  surmise. 

Intestine 

Cardia.  There  is  usually  a  flattish  cardia  consist- 
ing of  20  to  50  small  characteristic  cells  that  stain 
cross'  section  of  in-  rather  strongly  with  acid  carmine,  and  manifestly  dis- 
«Sdatiw°to  ?ho4°  coi-  charge  a  distinct  function.  The  intestine,  which  is 
thTiininKtroftUthee  in-  invariably  separated  from  the  oesophagus  by  a  deep  and 
prominent  constriction,  becomes  at  once  about  three- 
fourths  as  wide  as  the  body,  and  is  usually  made  up  of  cells  of  such  a 
size  that  about  8  to  20  are  required  to  build  a  circumference.  These  cells 
contain  numerous  granules  of  somewhat  variable  size,  often  so  arranged 


DIGESTION  (S.  S.  445)  143 

about  the  large  central  nucleus  as  to  give  rise  to  a  beautifully  regular 
appearance  simulating  tessellation.  As  a  rule,  the  columnar  lining  of  the 
intestine  (fig.  11)  is  not  very  refractive.  Owing  to  the  low  visibility  of 
this  lining,  and  the  difficulty  of  seeing  through  the  mass  of  granules  con- 
tained in  the  intestinal  cells,  the  lumen  is  usually  hard  to  decipher;  to- 
ward the  anus,  however,  it  may  become  more  distinctly  visible.  Occasion- 
ally, the  granules  are  so  few  or  so  transparent  that  the  contents  of  the 
intestine  can  be  seen  with  ease,  but  this  is  rather  exceptional. 

Granules.  The  structure  and  arrangement  of  the  granules  in  the 
intestinal  cells  of  Mononchus  lacustris  may  be  taken  as  somewhat  typical. 
The  granules  of  this  species  are  numerous  and  packed  rather  closely  in 
the  cells,  and  give  rise  to  a  more  or  less  distinct  tessellation.  Specimens 
fixed  with  Flemming  solution,  and  mounted  in  glycerine  jelly,  show  many 
of  the  granules  as  refractive  shells,  enclosing  a  relatively  large  inner 
spherical  mass,  which  appears  dark  or  light  according  to  the  nature  of 
the  focus  of  the  microscope.  This  structure  is  characteristic  of  some  of 
the  smallest,  as  well  as  some  of  the  largest,  granules.  These  appearances 
are  not  uniform  throughout  the  intestine,  the  shell-like  structures  being 
more  apparent  in  the  posterior  part  than  elsewhere,  and  less  apparent 
through  the  middle  portion  of  the  body,  where  the  granules  are  largest 
and  most  abundant. 

These  intestinal  granules  play  an  important  role  in  the  economy  of 
the  nema — some  of  them  are  in  fact  indispensable  intracellular  organs. 
Little  as  we  know  about  their  functions  in  detail,  it  is 
already  certain  that  they  have  to  do  not  only  with  the  ,,_, 
secretion  of  various  digestive  fluids,  but  also  with  the 
transformation  and  storage  of  the  digested  matter.  The  \|  c//  ^ 
granules  in  any  given  cell  may  be  of  several  kinds,  doubt- 
less serving  entirely  different  functions.  These  facts 
the  author  has  demonstrated  by  intra-vitam  staining. 

Digestion 

Food  Remnants.  The  digestive  fluids  of  the  mon- 
onch  must  be  well  fitted  for  dissolving  ceratin,  suppos- 
edly the  main  component  of  nematode  cuticle,  for  the 
cuticle,  as  well  as  most  other  parts  of  the  ingested  victim, 
disappears  completely  in  the  course  of  digestion.  The  parts  that  resist 
digestion  longest  are  the  spicula  of  male  nemas  and  the  oral  spears  of  the 
spear-bearing  sorts.  These  organs,  the  spicula  and  the  spear,  are  com- 
posed of  relatively  thick  layers  of  solid  "ceratin,"  and  furthermore  are 
protected  from  the  action  of  the  digestive  fluids  because  of  their  situation 
in  the  interior  of  the  ingested  nema,  and  hence  are  among  the  last  to  be 
dissolved.  Such  an  undigested  remnant,  a  spear  or  a  spiculum,  consti- 


144CS.S.446)  THE  MONONCHS 

tutes  one  of  the  most  frequent,  as  wJl  as  most  reliable,  bits  of  evidence 
concerning  thi  food-habits  of  mononchs. 

Voracity.  Mononchs  are  voracious.  Often  the  remains  of  several 
other  nemas  are  to  be  seen  in  the  intestine  of  a  single  one  of  them.  The 
writer  once  had  under  observation  a  specimen  that  had  swallowed  four 
large  rotifers  in  quick  succession,  all  tail-end  first.  The  file  of  rotifers 
could  be  clearly  seen  in  the  intestine  of  the  mononch.  Aquatic  mononchs 
are  fond  of  rotifers.  The  characteristic  "gizzards"  of  the  rotifers,  being 
rather  indigestible,  are  often  found  in  the  posterior  part  of  the  intestine. 

Rectum.  From  the  slightly  depressed  anus,  the  lips  of  which  are 
sometimes  rather  pronounced,  the  refractive  rectum,  usually  about  as 
long  as  the  anal  body  diameter,  extends  inward  and  forward,  and  is  sep- 
arated from  the  intestine  by  a  distinct  constriction.  There  is  no  pre- 
rectum,  though  the  contrary  impression  is  sometimes  created  by  a  con- 
striction caused  by  a  mural  commissure  (?)  some  little  distance  in  front 
of  the  rectum. 

Feces.  From  the  region  of  the  anus  relatively  powerful  transverse 
muscles  pass  obliquely  backward  to  the  body  wall,  and  find  their  proximal 
attachment  in  the  dorsally  submedian  regions.  These  anal  muscles  are 
more  strongly  developed  in  mononchs  than  in  most  nemas.  A  powerful 
defecating  apparatus  is  needful  to  such  gluttons,  since  their  feces  are 
sometimes  bulky,  owing,  apparently,  to  the  fact  that  the  contents  of  the 
intestines  of  their  victims  often  prove  indigestible.  Probably  this  indi- 
gestible material  is  to  a  considerable  extent  vegetable  in  its  nature;  at 
any  rate,  it  frequently  happens  that  the  feces  are  bulky,  and  this  fact 
seems  to  account  for  the  strong  development  of  the  rectum  and  the  anal 
muscles. 

Caudal  Glands;  Spinneret 

The  Cement.     The  caudal  glands,  when  present,  are  always  three  in 
number,  and  are  arranged  in  a  cluster  or  series  opposite  to  or  immedi- 
ately behind  the  anus.    If  the  tail  is  short,  the  foremost  gland  is  usually 
dorsal  while  the  two  submedian  glands  are  arranged 
side  by  side;  if  the  tail  is  long  all  three  may  be  ar- 
ranged tandem.     Apparently  there  are  always  three 
separate  ducts,  one  from  each  gland,  each  having  a 
separate  ampulla;  these  latter  are  arranged  side  by 
X750        — ^^^^       side  in  a  group  at  the  spinneret.    Often,  however,  the 
spinneret  is  simple  in  form  and  presents  ducts  that 

FIG.    13.  —  Mononch  .  .  J 

tail  showm*  the  three  form  only  indistinct  ampullae.  Some  idea  of  the  man- 
caudal  glands,  their  ,  .., 

ducts,  the  spinneret,     ner  and  rate  of  secretion  of  the  caudal  glands  may  be 

and    its    secretion  .  . 

<*<*.).  derived  from  an  examination  of  the  adjacent  illustra- 

tion, which  shows  a  spiral  mass  of  the  cement  substance  secreted  by  them. 
This  spiral  mass  was  coagulated  by  the  fixing  fluid  in  which  the  specimen 
met  its  death. 


SPINNERET  (S.  s.  447)  145 

Action  of  Spinneret.  The  structure  of  the  spinneret  is  very  similar 
to  that  of  Mononchulus,  a  related  genus  whose  unusually  large  spinneret 
has  proven  especially  favorable  for  detailed  study,  and  may  be  described 
as  follows.  The  three  somewhat  elongated  ampullae  at  the  ends  of  the 
caudal  ducts  empty  into  a  single  sac  located  in  the  spinneret.  From  the 
front  wall  of  this  sac  there  projects  backward  into  its  cavity  an  elongated 
element  whose  free  conical  distal  extremity  fits  into  the  outlet  of  the 
spinneret,  where  it  acts  as  a  plug  or  valve.  Apparently,  this  valve  must 
arise  through  an  invagination  of  the  sac  during  development.  The  plug 
is  withdrawn  by  muscles  attached  to  it  and  to  the  dorsal  body-wall  near 
the  end  of  the  tail.  A  contraction  of  these  muscles  elongates  the  sac  con- 
taining the  caudal  secretion  and  draws  the  plug  away  from  the  aperture 
of  the  spinneret,  thus  allowing  the  secretion  to  flow  out  through  the  termi- 
nal pore.  The  plug  appears  to  be  returned  to  its  position  and  held  there ' 
either  by  the  pressure  of  the  secretions  in  the  sac,  or  by  the  general  in- 
ternal body  pressure  exerted  on  it  through  the  sac.  Figure  5  shows  the 
similar  spinneret  of  a  mononch. 

Use  of  Spinneret.  In  any  genus  consisting  of  many  species  most  of 
which  have  caudal  glands,  aberrant  species  usually  occur  in  which  these 
organs  are  absent.  This  is  true  of  Mononchus.  A  spinneret  would  ap- 
pear to  be  a  particularly  useful  organ  to  a  predaceous  nema,  permitting 
it  at  will  instantly  to  cement  itself  to  a  relatively  fixed  object,  and  thus 
more  easily  master  an  active  victim ;  nevertheless,  about  one-fourth  of  the 
mononchs  have  no  trace  of  such  an  organ. 

The  lateral  fields  are  always  comparatively  well-developed,  and  are 
usually  one-third  to  one-fourth  as  wide  as  the  body.  The  cells  composing 
them  often  contain  spherical  granules  not  differing  greatly  in  size  from 
those  of  the  intestinal  cells.  No  cuticular  pores  have  ever  been  seen  con- 
necting elements  of  the  lateral  fields  with  the  exterior. 

Renette 

Nothing  is  known  about  the  structure  of  the  renette — in  fact,  it  is  not 
yet  definitely  known  to  exist  in  mononchs.  In  most  species  there  is  a 
ventral  pore  immediately  behind  the  nerve-ring,  which  bears  a  close  re- 
semblance to  the  excretory  pore  of  nemas  possessing  a  well-developed 
renette;  but  no  internal  structures  have  as  yet  been  found  to  connect 
with  this  pore. 

Central  Nervous  System 

The  nerve-ring  surrounds  the  oesophagus  somewhat  squarely  near  the 
front  end  of  the  middle  third  of  the  neck.  It  is  usually  well  developed 
and  easily  seen  —  a  distinct  refractive  collar  with  groups  of  nerve  cells 
both  in  front  of  it  and  behind  it.  Otherwise  than  this  very  little  is  known 
about  the  central  nervous  system  of  Mononchus. 


-  S.  448) 


THE  MONONCHS 


FIG.  14. — Female  M.  tri- 
churus.  This  mononch 
has  only  one  ovary.  The 
tail  is  very  long  and  slen- 
der and  quite  likely  is 
more  or  less  prehensile. 


1* 


Nerve  Commissures.  A  constriction  in  the  intestine  is  sometimes  ob- 
served at  a  point  not  far  in  front  of  the  rectum,  say  at  a  distance  equaling 
3  to  5  body  diameters.  This  constriction  is  sometimes  so  pronounced  as 
to  cause  the  posterior  portion  of  the  intestine  to  simulate  the  pre-rectum 
of  Dorylaimus.  There  is  here,  however,  no  true  pre-rectum.  The  con- 
striction seems  to  be  caused  by  mural  commissures  surrounding  the 
intestine.  The  writer  can 
only  suggest  the  possibility 
of  the  existence  of  special 
nerves  at  this  point,  which 
leave  the  ventral  field,  pass 
slightly  backward,  then  al- 
most immediately  become 
squarely  transverse,  encir- 
cling the  intestine  until  they 
are  very  near  the  dorsal 
field,  where  they  turn  sud- 
denly backward. 

Amphids 

If  is  almost  certain  that 
small  amphids  occur  on  all 
mononchs ;  the  writ- 
er found  them  pres- 
ent on  three-fourths 
of  the  known  spec- 
ies. As  their  gen- 
eral characters  have 
never  been  adequate- 
ly described,  their 
form  and  position 
are  specially  noted 
here,  as  well  as  more 
explicitly  in  the  var- 
ious illustrations. 
The  external  indica- 
tions of  the  amphid 
are  always  located 

GO  the  lateral  lines  somewhere  between  the  base  of  the  lips  and  a  poin* 
opposite  the  middle  of  the  pharynx.  The  periphery,  which  in  some  .cases 
may  be  unclosed  behind,  is  usually  more  or  less  elongated  or  elliptical  in 
form,  its  long  axis  lying  transversely  on  the  head.  These  amphids  are 
seldom  more  than  one-sixth  as  long  as  the  head  is  wide,  and  are  usually 


ttflal 
X450 


SEXUAL   ORGANS  (8.5.449)147 

very  difficult  of  observation.  They  are  most  easily  detected  when  viewed 
dorso-ventrally,  and  then  appear  as  refractive  oblique  elements  leading 
from  the  surface  of  the  head  inward  and  backward  through  the  trans- 
parent cuticle,  as  shown  for  instance  in  the  cases  of  subtenuis  and  regius 
(p.  167  and  140).  They  can  seldom  be  followed  more  than  a  short  dis- 
tance inward,  and  their  ultimate  internal  connections  are  unknown.  A 
nerve-ending  is  nearly  always  to  be  seen  in  the  cuticle  immediately  behind 
each  amphid. 

No  Eyes 

Mononchs  have  no  definite  organs  of  vision. 
Female  Sexual  Organs 

Organs  Mostly  Double.  Eggs.  Ovaries  and  Ova.  From  the  slightly 
elevated  and  rather  small  vulva,  the  prominent  refractive  vagina  leads 
inward  at  right  angles  to  the  ventral  surface  about  one-third  the  distance 
across  the  body.  Though  comparatively  small  in  size,  the  vulva  is  usually 
easily  located  on  account  of  the  refractive  nature  of  the  walls  of  the 
vagina.  In  nine-tenths  of  the  species,  the  internal  female  organs  are 
double,  and  symmetrically  reflexed,  though  in  some  cases  the  posterior 
branch  is  somewhat  smaller  than  the  anterior.  In  the  exceptional  species 
the  single  ovary  is  also  reflexed  (fig.  14).  The  ovaries  occupy  relatively 
less  space  than  is  usual  in  nemas — less  than  one-fourth  of  the  length  of 
the  body.  Owing  to  the  comparatively  great  length  of  the  neck,  the  vulva 
is  usually  located  somewhat  behind  the  middle  of  the  body  even  when 
the  sexual  organs  are  double  and  symmetrical,  and  may  occur  as  far 
back  as  the  junction  of  the  third  and  final  fourths.  Each  of  the  two  uteri  is 
about  twice  as  long  as  the  body  is  wide,  that  is  to  say,  of  a  size  to  receive 
one  or  two  eggs  only.  These  latter  are  nearly  always  smooth,  thin-shelled, 
ellipsoidal  or  elongated  in  contour,  and  appear  about  twice  as  long  as  the 
body  is  wide,  though  they  are  sometimes  somewhat  shorter,  and  more 
rarely  longer.  Only  in  a  single  species  are  the  shells  known  to  be  sculp- 
tured. The  shells  are  thick  in  obliquus.  In  all  the  species  examined  by  the 
writer,  the  eggs  are  deposited  before  segmentation  begins,  and  this  is 
presumably  true  of  the  great  majority,  if  not  of  all  the  species.  The 
reflexed  ovaries  extend  one-half  to  three-fourths  the  distance  back  to  the 
vulva  and  contain  a  score  or  so  of  ova,  which  near  the  blind  ends  are 
packed  in  several  rows — ova  that  by  increase  in  size  come,  each  one  in 
turn,  to  occupy  the  whole  of  the  width  of  the  organ  in  its  proximal  half 
near  the  flexure.  The  ovaries  are  rather  broad,  and  taper  relatively  little. 

Syngonism.  A  considerable  number  of  the  mononchs  are  syngonic, 
and  it  is  probable  nearly  all  of  them  are  so,  since  the  males,  if  found  at  all, 
are  nearly  always  rare.  Only  on  a  single  occasion,  so  far  as  records  go, 
have  males  been  found  to  be  as  common  as  the  females.  Of  most  species 


148(S.S.4SO) 


THE  MONONCHS 


the  males  never  have  been  seen.  At  a  time  previous  to  the  development 
of  the  vulva  the  gonads  of  the  female  produce  minute  spermatozoa,  which 
are  sent  forward  and  stored  in  a  special  portion  of  the  uterus  next  the 
proximal  end  of  the  ovary.  In  the  only  species  so  far  carefully  examined 
in  this  regard  these  minute  spermatozoa  are  known  to  be  functional,  at 
least  to  the  extent  that  they  enter  the  ova,  which  then  proceed  to  form 
polar  bodies  and  begin  to  segment.  However,  these  particular  investiga- 
tions, made  by  the  author  and  further  recorded  in  figure  2,  have  been 
confined  to  the  single  species  M.  longicaudatus.  Possibly  the  phenomena 
are  different  in  other  species. 

Male  Sexual  Organs 

Spicula.  The  tail  end  of  the  male  is  invariably  like  that  of  the  female 
in  general  form  and  size,  except  that  it  is  more  strongly  arcuate;  it 
differs  however,  in  some  instances,  probably  in  all,  in  the  possession  of 

comparatively  well-developed  papil- 


FIG.    15.  —  Tail   end   of  . 

M,  obtusus  after  Biitschii.   IK.  and  particularly  and  universally 

The    spicula    in    this    spe- 


cies are  exceptionally  long  in  the  existence  of  a  ventral  row  of 

and    slender.      The    male  o          ^_  ... 

papilla  (ppi.)  and  supple-  8  to  20  more  or  less  equidistant  sup- 

mentary   organs    are    very        .  ..... 

well  shown.    The  spicula  plementary    organs    immediately    in 

pr0tudabndare  front  of   the  anus.     The  two  well- 


gude 


bysienderacces 

S*.eft1e."  iiE  developed    arcuate    spicula    are 


of 


equal  size,  and  are  always  accompa- 
nied by  two  distinct  though  small  accessory  pieces,  a 
right  and  a  left.  Only  exceptionally  are  the  spicula 
long  and  slender;  usually  they  are  somewhat  uniformly 
arcuate,  and  appear  to  be  subacute  and  of  somewhat 
uniform  width  throughout,  at  least  when  viewed  in 
profile,  and  about  one  and  one-half  times  as  long  as  the 
anal  body  diameter.  Usually  each  is  strengthened  by  a 
median  longitudinal  refractive  piece.  They  are  never 
prominently  cephalated.  The  accessory  pieces  are  lo- 
cated some  little  distance  inside  the  anus,  alongside  the 
spicula,  which  they  may  appear  to  cross  when  viewed 
in  profile.  These  accessory  pieces  are  usually  a  little 
narrower  than  the  spicula,  and  2  to  4  times  as  long  as 
wide.  Distally  they  usually  end  in  two  subacute  points, 
often  so  arranged  as  to  form  a  small  U-shaped  figure.  When  at  rest  the 
accessory  pieces  usually  appear  as  if  at  about  right  angles  to  the  axis  of 
the  body.  They  are  not  cephalated. 

Supplementary  Organs.  Sperm.  The  supplementary  organs  vary  in 
number  up  to  twenty.  The  hindmost  is  located  immediately  in  front  of 
the  anus,  and  may  be  a  little  farther  removed  from  its  nearest  neighbor 


SYNGONISM 


(S.  s.451)  149 


FIG.  16.  —  Mononchus  ma- 
jor. I — Side  view  of  male. 
II  —  Side  view  of  head  of 
same.  Ill — Front  view  of 
head.  IV— Side  view  of  tail 
V.— Details  of  male  supple- 
mentary  organs. 

a,  mouth 

b,  lip-papilla 

c,  lip 


f,   pharyngeal  tooth 

S,  innervated  papilla  of  skin 

h,  oesophagus 

»,    base  of  pharynx 


flexure  in  testicle 
blind  end  of  testicle 
vas  deferens 
lip 


*,    accessory  piece 
u,  post-anal  i 

v,  spicula 


papillae 


iv,  ejaculatory  duct 

x,  ventral  row  male  papillae 

y,  an 


than  is  usually  the  case  in  the  remainder  of  the  series ;  thence  forward 
the  organs  are  about  equidistant.  Usually  they  are  more  or  less  con- 
tiguous, though  occasionally  they  are  separated  by  short  spaces,  especially 
anteriorly.  When  most  highly  de- 
veloped, each  is  a  convex-conoid, 
innervated,  very  minutely  papil- 
lated  or  echinulate,  more  or  less 
protrudable  organ,  connected  with 
the  interior  by  an  oblique,  indis- 
tinct element  along  the  axis  of 
which  a  nerve  passes  inward  and 
forward  to  join  the  ventral  nerve 
of  the  body  (v,  fig.  16).  It  would 
appear  that  these  organs  are  partly  l;n> 
tactile  and  partly  excitatory  in  *; 
function,  and  act  as  the  comple-  J;  ^jacSatM^duct 
ments  of  the  vulvar  papillae  of  the  r;  ^"fetory  duct 
female.  There  is  no  bursa.  The 
series  of  oblique  copulatory  mus- 
cles is  always  coextensive  with 
the  series  of  supplementary  or-  s-  three  anal  Rlands 
gans.  The  rather  short  testes  seem  to  be  invariably  two  in  number  and 
are  outstretched  in  opposite  directions.  The  spermatozoa  of  males  are 
minute  and  present  a  more  or  less  vermiform  nucleus. 

Self -Fertilizing  Females;  Syngonism 

Males  Rare.  Conjugation  of  Syngonic  Gametes.  No  trait  of  mon- 
onchs  is  more  interesting  than  the  capacity  of  the  female  to  reproduce 
without  the  intervention  of  a  male — by  a  peculiar  sort  of  hermaproditism 
called  syngonism.  Of  most  of  the  species  no  males  are  known;  in  the 
remaining  species,  almost  without  exception  the  males  are  very  scarce, 
and  only  in  exceedingly  rare  cases  are  they  present  in  anything  more 
than  small  numbers.  Usually  hundreds,  and  even  thousands,  of  speci- 
mens may  be  examined  without  the  discovery  of  a  single  male.  How 
then  do  the  females  reproduce?  The  answer  is  singularly  interesting, 
for,  as  already  explained,  the  females  fertilize  their  own  eggs  by  means 
of  spermatozoa  which  they  themselves  produce  in  the  same  gonad.  In 
the  mononchs  these  spermatozoa  produced  by  females  are  so  exceedingly 
minute  that  they  have  hitherto  escaped  notice  (fig.  2).  Notwithstanding 
its  small  size,  the  syngonic  sperm  cell  appears  to  be  functional.  It  enters 
the  egg,  expands,  and  approaches  the  nucleus  of  the  egg,  which  mean- 
while throws  off  polar  bodies  and  later  proceeds  with  segmentation. 
Observations  have  not  yet  extended  beyond  this  point,  but  it  saems  alto- 


150<S-S.4S2)  THE  MONONCHS 

gether  likely  that  these  minute  spermatozoa  produced  by  mononch 
syngones  act  in  what  would  be  called  a  normal  manner,  and  as  the  sperma- 
tozoa are  known  to  do  in  other  syngonic  nemas  in  which  they  are  of  much 
larger  size,  e.  g.  Rhabditis. 

Abundance;  Distribution 

Frequency  of  Mononchs.  Long  ago  Biitschli  declared  mononchs  to 
be  among  the  commonest  of  nemas,  an  assertion  that  has  been  corrobo- 
rated by  all  investigators  in  this  field,  hardly  any  of  whom  have  failed  to 
note  a  number  of  species,  occasionally  new  ones.  Our  knowledge  of  the 
genus  has  been  augmented  in  this  way  by  de  Man,  Micoletzky,  Ditlevsen, 
Steiner,  Hofmanner,  Menzel,  Daday,  and  the  writer,  until  at  the  present 
time  about  sixty  species  are  known.  Doubtless  this  number  will  be  very 
largely  increased  by  future  researches. 

Geographic  Distribution.  Variety  of  Habitat.  Mononchs  are  found 
in  all  the  habitable  regions  of  the  world.  They  inhabit  the  soils  and 
fresh  waters  of  every  clime,  occurring  even  at  great  depths  in  lakes  and 
at  very  high  altitudes  on  mountains.  While  we  have  only  just  begun  to 
learn  the  details  of  their  geographic  distribution,  it  is  already  manifest 
that  some  species  are  cosmopolitan.  Several  species  occur  both  in  Europe 
and  in  North  America,  and  a  few  of  these  same  species  are  known  also 
from  Australia.  Considering  the  small  number  of  observations  hitherto 
made  along  this  line,  it  seems  safe  to  predict  that  many  of  the  species 
will  be  found  to  be  cosmopolitan.  Some  species  adapt  themselves  to  sur- 
prisingly varied  conditions.  Mononchus  longicaudatus,  for  instance,  is 
known  from  the  tropics,  from  temperate  regions,  and  from  very  cold 
regions,  and  inhabits  both  soil  and  fresh  water.  Another  species,  Mon- 
onchus brachyuris,  is  known  both  from  warm  springs  and  from  cold 
Alpine  lakes. 

Abundance  in  Arable  Soil.  Mononchs  occur  in  great  numbers  in 
arable  soil.  On  one  occasion  the  writer  estimated  that  at  least  thirty 
millions  of  mononchs  per  acre  were  present  in  the  top  six  inches  of  a 
field  of  maize  in  New  Jersey,  and  the  actual  number  present  may  have 
been  much  greater.  They  are  regularly  present  in  practically  all  arable 
land  of  a  sandy  or  loamy  nature. 

The  very  numerous  introductions  of  living  plants  into  the  United 
States,  through  the  agency  of  the  Office  of  Seed  and  Plant  Introduction 
of  the  Department  of  Agriculture  and  other  agencies,  has  brought  about 
simultaneously  the  introduction  of  many  species  of  Mononchus.  Nemas 
existing  in  the  soil  about  the  roots  of  introduced  plants  are  often 
placed  under  favorable  conditions  for  propagation  in  this  country.  It  is 
therefore  certain  that  an  unusual  variety  of  mononchs  exists  in  the  soils 
of  the  United  States. 


GENUS  MONONCHUS  (S.S.453)i5j 

Interplay  of  Organisms.  There  are  regions  where  certain  nematode 
diseases  of  crops  are  very  destructive,  while  other  regions,  the  climate 
and  soil  conditions  of  which  are  apparently  similar,  suffer  but  little,  or  at 
least  to  a  lesser  degree,  so  far  as  we  know.  In  such  cases  it  is  permis- 
sible to  suppose  that  the  nematodes  in  the  area  where  the  lesser  damage 
is  done  are  held  in  check  by  some  as  yet  unknown  agent.  Is  it  not  pos- 
sible that  the  mononchs  play  some  such  role  as  this,  and  that  just  as  cer- 
tain insects  hold  other  insects  in  check,  so  certain  nemas  hold  other  nemas 
in  check? 

We  know  relatively  little  about  the  life  history  of  most  of  the  mon- 
onchs, and  as  yet  very  little  about  the  possibility  of  controlling  their 
growth.  One  species,  Mononchus  longicaudatus,  occurs  at  certain  times 
in  almost  inconceivable  numbers  in  the  sand  of  the  slow  filter  beds  of  the 
water  works  of  cities.  Near  the  end  of  the  period  of  use  the  top  layers 
of  the  sand  in  these  filter  beds  sometimes  become  in  reality  a  huge  culture 
of  this  species.  The  observations  suggest  at  least  the  possibility  of  culti- 
vating this  species  on  a  large  scale,  should  it  prove  desirable  to  do  so. 

The  discovery  that  the  genus  Mononchus  is  very  large  and  to  a  con- 
siderable extent  composed  of  common  and  cosmopolitan  species  that  feed 
upon  injurious  plant-infesting  organisms,  suggests  so  many  new  lines  of 
research  in  soil  biology  as  to  make  it  desirable  that  a  clear  and  connected 
account  of  the  members  of  the  genus  be  available  to  investigators.  This 
need  is  increased  by  the  fact  that  the  literature  is  a  scattered  and  frag- 
mentary one,  difficult  to  assemble.  To  these  facts  it  must  be  added  that 
most  of  the  new  observations  herein  recorded  have  been  made  upon 
species  previously  unknown. 

II 

GENUS  MONONCHUS  BASTIAN,  1866 

This  genus  is  composed  of  non-marine,  free-living  nemas,  with  naked 
cuticle  and  obscure  amphids,  and  having  a  plain  oesophagus  preceded  by 
a  broad — that  is,  non-tubular — pharynx,  armed  with  1  to  3  more  or  less 
immobile  teeth  of  which  the  dorsal  is  largest,  and  supplied  with  6  power- 
ful papillated  lips.  Ovaries  reflexed,  usually  two.  Testes  two,  out- 
stretched ;  spicula  two,  equal,  simple,  as  are  their  small  accessories ;  there 
is  a  pre-anal  ventral  row  of  supplementary  organs. 

GENERA  SIMILAR  TO  MONONCHUS,  WITH  DISTINGUISHING  CHARACTERS 


Oncholaimns 

Anonchus 

Microlaimtts 

Irottus 

Nannonchus 

Oionchus 

Mononchtilus 


Marine;  sometimes  found  in  brackish  soils.     Has  cephalic  setse. 
Has  spiral  amphids,  and  cephalic  setse. 
No  thick  muscular  lips;  amphids  circular. 
Pharynx   tubular;    teeth  movable   radially. 
Has  spiral  amphids  and  cephalic  setae. 
Pharynx  filled  by  single  tooth,  which  is  really  spear-like. 
Quite  similar.     Has  much  larger  (ventral)  spinneret;  strongly  developed 
lateral  fields;  smaller  pharynx;  female  organ  single. 


152  (s-s- 45-0 


THE   MONONCHS 


Mononchus  Bastian,  1866 


ay  in  pharynx  or  higher,  usually  massive 
MONONCHUS  Cobb; 


Subgenera 

and 
Species 

1.    MONONCHUS 


DORSAL  TOOTH  midw  .    _  , 

Tooth  not  opposed  by  denticles;   subg. 

type,  M.  truncatus  Bast.;  pharynx  about  2  to  3  times  as 
long  as  wide,  goblet-shaped  or  ellipsoidal;  wall  smooth  or 
transversely  striated;  spinneret  usually  present;  males  of 
about  half  the  species  known;  female  organs  double  (except 
monhystera) 
Dorsal  tooth  faced  by  2  ventrally  submedian  teeth 

Teeth  retrorse   (tridentatus  de  Man  1876) 

Teeth  not  retrorse 

Tail  conoid,  then  cylindroid;  body  7  mm.  long (rex  Cobb  1904) 

Tail  simply  conoid;  body  3  mm.  long  or  less 

Spinneret  and  caudal  glands  absent exilis  n.  sp. 

Spinneret  and  caudal  glands  present  . . 

Contour    of    the    head    angular;    labial    papillae    16     radiatus  n.  sp 
Contour    of    the    head    rounded;    labial    papillae    12 

Pharynx  longer  than  the  head  is  wide palustris  n.  sp. 

Pharynx  only  as  long  as  the  head  is  wide teres  n.  sp. 

Dorsal  tooth  not  faced  by  submedian  teeth 

Ovary  1;  pharynx  not  much  longer  than  wide monhystera  n.  sp. 

Ovaries  2;   pharynx  toward  twice  as  long  as  wide 
Tail  simply  conoid,  8  per  cent  or  less 
Spinneret  none 

Pharynx  over  half  as  wide  as  the  head vorax  n.  so. 

Pharynx  not  over  half  as  wide  as  the  head 

Length  about  1  mm.;  tooth  midway,  small,  digitate     parvus  de  Man  1879 
Length  1.5  to  2  mm.;  tooth  beyond  midway,  massive     papillatus  Bastian  1866 
Spinneret  present 
Body  2  mm.  long 

Form  of  the  tail  regular 

Form  of  the  tail  somewhat  irregular 

Body  3  to  4  mm.  long 

Tooth    midway,    amphids   a    little   behind    the   lips     maior  Cobb  1893  11 

Tooth  and  amphids  at  the  base  of  the  lips gerlachei  de  Man  1904  12 

Tail  conoid,  then  cylindroid,  about  10  per  cent  or  more 

(Esophagus  15  per  cent fovearum  (Dujardin)  Bastian  '66  13 


intermedius  Cobb   1893 
tenuicaudatus  Stefanski  1914 


obtusus  n.  sp. 
tunbridgensis  Bastian  1866 


longicaudatus  Cobb  1893 

2.    SPORONCHULUS 


(Esophagus  22  per  cent  or  more 

Buccal  cavity  toward  2  times  as  long  as  head  is  wide 

Spinneret  armed  with  2  very  small  setae megalaimus  n.  sp. 

Spinneret  not  armed  with  setae macrostoma  Bastian  1866 

Buccal  cavity  only  about  half  as  long  as  head  is  wide 

Labial  papillae   setose    

Labial  papillae,  at  least  the  outer,  not  setose 

Pharynx  54  as  wide  as  head;  body  1.5  mm.  long 
Pharynx    */2    as  wide  as  head  or  more;   body  2 

to  3  mm. 

Cavity  about  2  times  long  as  wide;  tooth  acute    truncatus  Bastian  1866 
Cavity  about  3  times  as  long  as  wide;   tooth 

sub-acute 

Inner  labial  papillae  large;  tail  sub-conoid.,     dadayi  Micoletzky   1904 
Inner    labial     papillae    normal;     tail    finally 

cylindric 

Tooth  opposed  by  numerous  denticles  on  opposite  wall 

Arrangement  of  the  denticles  irregular;  characters  otherwise 
as  in  Mylonchulus;  subg.  nov.  SPORONCHULUS; 
type  S.  dentatus  n.  sp. 

The  tooth  behind  midway;  spinneret  present;  anus  at  92; 'f    recessus  n.  sp. 
The  tooth  in  front  of  midway;  no  spinneret;   anus  at  96; 

Denticles  about  20;  pharynx  half  as  wide  as  the  head;  T    dentatus  n.  sp. 
Denticles  about  50;  pharynx  one-third  as  wide  as  the  head 
Arrangement  of  the  denticles  orderly 

Denticles  along  a  ventral,  longitudinal  pharyngeal  rib; 
subg.  PRIONCHULUS  Cobb;  type  Pr.  muscorum 
(Dui.)  Bast.;  pharynx  ellipsoidal,  about  2  times  long 
as  wide;  males  of  one  species  known;  female  organs 
double;  no  spinneret 

Eggs  punctate  or  echinulate   punctatus 

Eggs  not  punctate  or  echinulate 

Length  2.5  to  3.4  mm.;  vulva  at  65  per  cent;  anus  at 
94  per  cent 

Width  3.6  per  cent;  denticles  forward  pointing muscorum   (Duiardin)   Ba 

Width  2.3  per  cent;  denticles  inward  pointing longicollis  n.  sp. 

Length  4  mm.;  vulva  at  55  per  cent;  anus  at  97  per  cent  spectabilis  Ditlevsen  1911 
Denticles  in  transverse  rows  on  2  sometimes  confluent,  sub- 
median,  rasp-like  areas,  often  with  2  very  small  sub- 
median  teeth  at  their  bases;  subg.  MYLONCHULUS 
Cobb;  type  M.  minor  Cobb;  pharynx  goblet-shaped, 
tooth  more  or  less  arcuate;  smaller  species  of  which 


iecurrens  n.  sp. 


21a 
21c 


3.    PRIONCHULUS 


sp. 


'66  23 
24 
25 


KEY   TO   GENUS  MONONCHUS 


(S.  S.  455)  153 


the  males  are  unknown   (except  tennis) ;  female  organs 
double   (except  index  and  reverses) ;  spinneret  present 
(except  similis) 
Ovary   1;   tail   rapidly  diminished,  then   digitate 

Vulva  behind  the  ovary;  denticles  normal 

Vulva  in  front  of  the  ovary;  denticles  few 

Ovaries  2;   tail  not  digitate   (Ex.  perhaps  sigmaturus) 
Dorsal  tooth  somewhat  digitate,  relatively  small 

Refractive  ring  about  pharynx  in  front  of  tooth 

Refractive  ring  about  pharynx  not  prominent 

Dorsal  tooth  massive,  not  digitate 

Head  rounded,  denticles  in  about  12  rows 

Head  truncate,  denticles  in  2  to  6  rows 

Rows  of  denticles  2   

Rows  of  denticles  4  to  6 

Denticles  about  4  rows;   spinneret  small 

Denticles  about  6  rows;  spinneret  larger 
Tail  bent  ventrally  near  the  middle 

Caudal  setae  none ;  tail  conoid   

Caudal  setae  (3  pairs)  present;  tail  not  conoid 
Tail  arcuate  or  straightish 

Width  of  adults  2.3  per  cent 

Width  of  adults  2.7  per  cent  or  more 

8audal  glands  and  spinneret  absent 
audal  glands  and  spinneret  present 

Eggs  thick  shelled   

Eggs  thin  shelled 

Buccal   striae    faint  if  any;   anus  94  to 
96  per  cent 

Species  aquatic   • 

Species  not  aquatic 

Buccal  striae  more  pronounced;  anus  98 

per  cent 
Spinneret  finally  dorsally  recurved.. 

Spinneret  not  dorsally  recurved 

DORSAL  TOOTH  and  others  small,  basal  or  nearly  so   (Exc.  44) 
Teeth     retrorse,     small,     basal,    exceptionally    midway;     subg. 
ANATONCHUS  Cobb;  tvpe  A.  tridentatus  de  Man;  large 
species  with  roomy  elongated  pharynx  and  smallish  retrorse 
teeth;    tail   long   and   usually  becoming  cylindroid;    female 
organs  double;   males  of  most  of  the  species  known 
Body  2  to  4  mm.;  teeth  equal,  midway;  anus  90  per  cent.... 
Body  5  to  6  mm.;  teeth  sub-basal;  anus  80  to  85  per  cent 

Submedian  teeth  equaling  the  dorsal;  body  6  mm 

Submedian  teeth  smaller  than  the  dorsal;  bodv  5  mm 

Teeth  not  retrorse,  small,  9r  even  minute;  subg.  IOTONCHUS 
Cobb;  type  I.  gvmnolaimus  Cobb:  large  species  with  roomy 
elongated  -harynx  having  longitudinal  ribs;  tail  rather 
long,  and  often  slender;  males  of  more  than  half  the 
species  known:  female  organs  double  or  single;  most 
species  with  spinneret 
Ovary  single;  1  to  3  rudimentary  basal  teeth 

Tail  digitate;  3  sub-equal  vestigial  teeth 

Tail  not  digitate- •  1  dorsal  tooth,  remainder  faint  or  none 

Posterior   extremity   setaceous    

Posterior  ext«-°mity  slender  but  not  setaceous 

Pharynx  as  long  as  wide;  few  submedian  denticles... 
Pharynx  about    2  times  long  as  wide;  faint  submedian 

teeth 
Amphid   simnle;   buccal  wall  thin,  transversely  striated 

Amphid  duplex;  buccal  wall  thick,  not  striated 

Ovaries  2;  1  t"  3  small,  sub-basal  teeth 

Body  4  to  7  mm.;  tail  finally  cylindroid;  3  teeth 
Spinnerer  present;  lips  rather  plain 

Length  4  mm.;  anus  90  per  cent;  the  3  teeth  subequal 
Length  6  to  7  mm.;  anus  80  per  cent;  submedian  teeth 

smaller    

Spinneret  none;  lips  striated  lengthwise  . . ._ 

Body  1  ti    4  mm.;  tail  conoid;  1  tooth,  sometimes  denticles 
Anus  .-*   about  86  per  cent;   tail  conoid,  or  at  last  sub- 

cylindroid 
Lips  not  set  off  by  constriction;  onchi  unequal  or  one 

Onchus  with  small  companions;  head  rounded 

Onchus  one  only;  head  truncate;  pharynx  striated... 
Lips  set  off  by  a  deep  constriction;  onchi  three,  equal 
Anus  at  about  94  per  cent;  tail  simply  conoid 

Dorsal  tooth  small,  others  basal,  minute,  indefinite. . . . 
Dorsal  tooth  distinct 

Buccal  cavity  half  as  wide  as  long:  tooth  sub-basal.. 
Buccal  cavity  as  wide  as  long;  main  tooth  basal 

Spinneret  present   

Spinneret  none    


4.    MYLONCHULUS 

index  Cobb  1907 
reversus  n.  sp. 


obtusicaudatus  Daday  1901 
brachyuris  Biitschli  1873 


denticulatus  n.  sp. 
sparsus  n.  sp. 
micrurus  n.  sp. 


incurvus  n.  sp. 
sigmaturus  n.  sp. 

subtenuis  n.  sp. 
subsimilis  n.  sp. 
obliquus  n.  sp. 


lacustris  Cobb  1915 
polonicus  Stefanski  1915 
minor  Cobb  1893 


brevicaudatus  n.  sp. 
japonicus  n.  sp. 


ANATONCHUS 


tridentatus  de  Man  1876 


gracilicaudatus   n.  sp. 
dolichurus  Ditlevsen  1911 


6.    IOTONCHUS 

digiturus  Cobb  1893 

trichurus  n.  sp. 

(bathybius  Micoletzky  1913) 


gvmnolaimus  Cobb  1893 
consimilis  n.  sp. 


rex  Cobb  1904 
regius  n.  sp. 


bathybius  Micoletzky  1913 
similis  Cobb  1893 
fasciatus  n.  sp. 

studeri  Steiner  1914 
zschokkei  Menzel  1913 

brachylaimus  n.   sp. 
acutus  n.  sp. 


THE  MONONCHS 


1.  M.  exilis,  n.  sp.     The  cylindroid  neck  ends  in  a  rounded  head  with  a  dis- 
tinctly expanded  lip  region.    The  large  pyriform  pharynx  is  armed  with  three  sub- 
equal  teeth.    The  wider  anterior  part  of  the  pharynx  is  two-thirds  as  wide  as  the 
*  head.     The  apices  of  the  teeth  are  midway, 

1.8      6.2      27.      '78'15      98.2  the  dorsal  one  being  a  little  the  farthest  for- 

1.6      1.8       2.          2.3         \.  m   ward.      Amphids    somewhat   behind   the   lips, 

1.6      6.        24.      -M-38      98.  but  farther  forward  than  the  teeth,  consisting 

1.6'    1.8       2.        2.2         1.2  of   somewhat   rectangular  markings   one-fifth 

as  wide  as  the  head,  longest  in  the  transverse  direction,  and  with  the  lateral  and 
front  margins  plainer  than  the  posterior.  Lining  of  the  oesophagus  not  so  promi- 
nent as  in  most  mononchs.  Intestine  greenish,  finely  granular,  obscurely  tessellated. 
Cardia  long  and  plainly  to  be  seen  through  the  flat,  colorless  pseudo-bulb  at  the 
beginning  of  the  intestine.  The  rectum  has  a  thick  lining  of  highly  refractive 
ceratin,  and  is  a  prominent  organ  one  and  one-half  times  as  long  as  the  anal  body- 
diameter.  Terminus  about  one-fourth  as  wide  as  the  base  of  the  tail.  The  very 
broad  vulva  is  only  slightly  elevated.  Posterior  sexual  branch  only  two-thirds  as 
long  as  the  anterior.  On  the  male  there  is  a  row  of  about  14  equidistant,  rather 
closely  approximated  ventral  ridges  in  front  of  the  anus,  extending  forward  a  dis- 
tance equal  to  3  tail-lengths.  These  do  not  bear  any  prominet  papillae.  The  body 
is  somewhat  thicker  in  the  region  of  these  ridges.  Spicula  linear,  uniformly  5  /j.  in 
diameter  when  seen  in  profile,  the  proximal  end  being  in  no  way  distinguished  from 
the  rest  of  the  shaft.  The  accessory  pieces  appear  to  rest  rather  closely  against  the 
distal  halves  of  the  spicula. 

Found  about  the  roots  of  moss,  Moss  Vale,  New  South  Wales,  1894.    Examined 
in  water  after  fixation  with  osmic  acid. 

2.  M.  radiatus,  n.  sp.   The 
amphids    of   this    rather    small 


3.3       9. 


30. 


95. 


.8  mir 


2.2        2.8       2.8       2.3       2.2 

but  elegant  species  are  minute  and  inconspicuous,— about  one- 
eighth  as  wide  as  the  corresponding  part  of  the  head.  The 
granules  of  the  intestine  are  largest  posteriorly,  where  they  are 
about  one-half  as  wide  as  the  spinneret.  The  intestine  is  not 
tessellated.  The  tail  is  markedly  arcuate,  its  spinneret  about 
one-fifth  as  wide  as  its  base.  Anus  very  slightly  raised.  Caudal 
glands  rather  small,  elongated.  Sexual  organs  apparently  double  and  symmetrically 
reflexed. 

Description  derived  from  a  single  young  specimen  from  a  cranberry  bog  in  New 
Jersey,  U.  S.  A.    Flemming  solution  to  glycerine.    Fig.  17.** 

3.     M.  palustris,  n.  sp.     Intestine  12  to  15  cells  in  girth,  more  or  less  distinctly 
"#»  J    2.7      8.      30.      '62'15      97.  tessellated.     Tail  arc- 

jT 27s  27e 27?  1.9  >  1-4  IBra  uate,  its  rather  conoid 
spinneret  about  one-fifth  as  wide  as  its  base.  Caudal  glands 
broad  and  saccate,  their  ampullae  occupying  most  of  the 
posterior  half  of  the  tail.  The  elongated  eggs  are  about 
twice  as  long  as  the  body  is  wide,  and  occur  one  at  a  time 
in  each  uterus.  The  rather  small,  tapering  ovaries  contain 
8  to  10  ova  arranged  more  or  less  irregularly. 

From  a  white  cedar  swamp,  Jefferson  County,  Wis- 
consin, U.  S.  A.  Feeds  upon  rotifers  and  probably  upon 
other  nematodes,  which  it  appears  to  masticate  (page  443, 
fig.  10).  Sublimate  to  balsam.  Fig.  18. 

^*  This  decimal  formula  for  nemas  is  explained  in  the  appendix. 

**  The  species  figures  have  the  same  magnification  throughout,  so  that  the  reader  may  guage  the 
relative  sizes. 


SUBGENUS  MONONCHUS 


(S.S.457)  155 


4.  M.  teres,  n.  sp.     This  comparatively  small,  simple  form  has  2  submedian 
teeth  of  equal  size.     Walls  of  the  intestine  with  numerous  granules  of  rather  uni- 
form size,  giving  rise  to  a  faint  tessellation ;  the  granules  such  that  2  to  3  would  be 
required   to   span   one   of   the    3.9      12.      35.      60Y      94. 

amphids.     Tail  rather  strongly    3~4       37§ 375 372 2.^      '    " 
arcuate,  its  fairly  well  developed  spinneret  about  one-fifth  as  wide 
as  its  base.     Caudal  glands  somewhat  elongated,  their  small  but 
rather  conspicuous   ampullae  nearly  filling  the  posterior  fifth  of 
the  tail. 

Description  prepared  from  a  single,  more  or  less  shrunken  speci- 
men, found  in  the  sphagnum  of  a  pot  in  which  blueberry  plants 
were  being  cultivated.  Bears  a  general  resemblance  to  papillatus,  but  differs  in  the 
form  of  the  pharyngeal  teeth  and  of  the  terminus.  Flemming  solution  to  glycerine. 
Fig.  19. 

5.  M.  monhystera,  n.  sp.    Amphids  not  seen.    Lining  of  the  rectum  and  of  the 
intestine  rather  distinct  and  refractive.    Intestine  only  faintly  tessellated,  if  at  all. 

3.3      9.7      27.     '7819     94  Tail  arcuate.  rather 

37 37s  §76  372  27s~  1-1  M  blunt,  without  spin- 
neret. From  the  rather  conspicuous,  more  or  less  elevated 
vulva,  the  vagina,  which  is  two-thirds  as  long  as  the  body  is 
wide  and  tubular,  extends  obliquely  inward  and  forward. 
Nothing  definite  is  known  with  regard  to  the  eggs  or  the 
form  of  the  ovary. 

Found  about  the  roots  of  orange  trees,  Bahia,  Brazil.  Bears 
a  general  resemblance  to  M.  papillatus,  but  has  only  one 
ovary.  This  species  is  nemativorous.  Flemming  solution  to 
glycerine.  Fig.  20. 

6.  M.  vorax,  n.  sp.     This  voracious  species  has  a  large  mouth  cavity  and  the 
oesophagus  is  therefore  at  first  slightly  swollen.     Intestine  12  to  20  cells  in  girth, 
not  tessellated.    The   2.7      8.      27.        >67'22      92. 

terminus  of  the  arc- 


1.4    BE 


2.1       2.3       2.7  2.6  1.6 

uate  tail  is  about  one-seventh  as  wide  as  its  base.     The 

elongated  eggs  are  about  twice  as  long  as  the  body  is 

wide.     Each  ovary  contains  about  30  developing  ova, 

arranged  irregularly.     Small  sperm  cells  were  seen  in 

abundance  at  the  flexure,  in  a  condition  indicating  that 

the  species  is  syngonic. 

Found  in  soil  from  a  white  cedar  swamp  in  Wiscon- 
sin, and  from  a  cranberry  bog  in  New  Jersey,  U.  S.  A. 

This  is  apparently  a  voracious  feeder  on  other  nema- 
todes.  Remains  of  Dorylaimus 
and  Ironus  were  seen  in  the 
intestine.  Resembles  M.  mac- 

mr t* -~f—l       \^~ft  rnstoma,  but  the  tail  is  conoid  and  has  no  spinneret.     Sub- 

limate to  balsam.    Fig.  21. 

T.  M.  parvus  de  Man.  De  Man  mentions  the  presence 
of  minute  teeth  at  the  base  of  the  pharynx,  near  the  be- 
3.1  -  9.5  29.  *63<  93.  ginning  of  the  oesoph- 

17 ^ ^ gTj; — ^7—  l.l  n»     agus.     Lining  of  the 

oesophagus  well  developed.     Intestine  apparently  about  10 
to  12  cells  in  girth,  tessellated.     Rectum  somewhat  shorter 
than  the  anal  bodv-diameter.     Tail  arcuate;  its  terminus  only  about  one-eighth  a» 


156(s-s-458>  THE   MONONCHS 

wide  as  its  base.    An  egg  seen  in  the  uterus  measured  100  ^  in  length.     It  is  not 
certain  that  caudal  glands  are  present. 

Knowledge  of  this  species  rests  very  largely  on  the  observations  of  Dr.  J.  G.  de 
Man,  who  says  that  it  is  an  active  species,  common  in  sandy  soils  of  the  dune  dis- 
tricts of  Holland.  Occurs  also  in  Germany,  according  to  Brakenhoff,  whose  speci- 
mens, however,  have  the  dorsal  tooth  close  to  the  lips  instead  of  midway  as  in  the 
type  form.  Fig  22,  previous  page  (after  de  Man). 

8.  M.  papillatus  Bastian.    Glands  are  present  in  the  segments  of  the  oesophagus, 
and  are  most  strongly  developed  in  the  posterior  half.    The  secretion  of  the  glands 

co,27  in  the  dorsal  segment 

3.        9.3        2b.         *bl"-'        93.  .    . 

2.6    3.5       3.8       4.3         2.4  pours  into  the  lumen 

of  the  oesophagus  through  a  minute  pore  near  the  middle  of 
the  neck,  a  short  distance  behind  the  nerve-ring.  Under  favor- 
able conditions  lenses  of  the  highest  power  show  transverse 
striae  to  be  interrupted  on  the  lateral  lines,  where  there  are  2 
^  refractive  longitudinal  striations  very  close  together.  What 
appears  to  be  an  ordinary  ventral  renette  pore  is  found  a  short 
xfso  distance  behind  the  nerve-ring.  The  writer's  investigations 
prove  this  species  to  be  syngonic.  The  longitudinal  ribs  of  the  pharynx,  probably 
3  in  number,  are  a  little  more  prominently  developed  than  usual.  Occasionally  a 
subventral  or  submedian  rib  of  the  pharynx  shows  traces  of  most  exceedingly  fine 
denticles.  Only  the  most  careful  examination  of  favorable  specimens  shows  these 
denticles.  The  writer  has  never  observed  a  denticulated  ventral  rib  like  that  of 
muscorum,  as  mentioned  by  Menzel. 

A  common,  voracious,  cosmopolitan,  nemativorous  species.  Found  in  many  parts 
of  Europe  and  of  the  United  States,  and  also  in  Hawaii,  Australia,  South  America 
and  Asia.  Fig.  23.  See  also  fig.  8. 

9.  M.  intermedius  Cobb.     Truncate  head  having  6  lips,  each  with  2  papillae. 
The  elongated-oval  amphids  are  half  as  wide  as  the  base  of  the  lip.     The  rather 
long,  goblet-shaped  pharynx  is  half  as  long     2.5      7.4      24.      '6i'35      94. 

as  the  head  is  wide,  and  presents  a  mod-  2.4  2.4  2.8  3.3  2.4 
erate-sized  dorsal  tooth  two-thirds  the  way  from  the  base  to  the  lips.  The  intes- 
tine, whose  commencement  is  marked  by  the  presence  of  a  pseudo-bulb,  shows  a 
rather  indistinct  tessellation.  What  appears  to  be  a  ventral  renette  pore  occurs 
just  behind  the  nerve-ring.  The  lateral  fields  are  one-fourth  as  wide  as  the  body. 
Caudal  glands  are  present  in  the  conical,  arcuate  tail.  Spinneret  almost  pointed. 
Anus  depressed,  consequently  conspicuous.  Vulva  conspicuous.  The  reflexed  por- 
tions of  the  ovaries  extend  one-half  way  back  to  the  vulva. 

Found  about  the  roots  of  sugar  cane,  Harwood,  Clarence  River,  New  South 
Wales,  Australia..  Examined  in  water  after  fixation  with  osmic  acid  vapor. 

10.  M.  tenuicaudatus  Stefanski.    The  lips  are  said  to  bear  6  large,  spheroidal 
papillae.    A  transverse  element  is  said  to  traverse  the  wall  of  the  pharynx  opposite 

?      ?     21.      '50+*      94.  the    apex    of    the 

4-         ^  dorsal    tooth,    and 

to  bear  2  slightly  curved  projections.  The  oesophagus 
is  muscular.  At  first  the  tail  diminishes  regularly  in 
diameter,  but  presents  2  swellings  in  the  posterior  part. 
Found  among  algae,  in  the  Rhone  River,  Switzer- 
land. This  species  is  said  to  resemble  M.  macrostoma 
Bastian  in  the  form  of  the  buccal  cavity,  but  to  differ 
from  that  species  in  the  details  of  the  structure  of 
the  mouth,  as  well  as  in  the  form  and  length  of  the 
tail.  Fig.  24,  after  Stefanski.  \\\  ^O>  X  750 


SUBGENUS  MONONCHUS 


(s.  s.  459)  157 


ii.  M.  major  Cobb.  Labial  papillae  of  the  inner  row  each  with  3  (?)  nerve- 
endings.  Amphids  slightly  farther  forward  than  the  apex  of  the  dorsal  tooth, 
small.  Lateral  fields  one-fifth  as  wide  as  the  body.  Intestine  composed  of  rather 

small    cells, 
3.4  mm      , 

snowing    an 


.6       6. 


19. 


'55 


25 


95. 


2.6 


2.9 

-M-45 


1.5 


indistinct    tes- 

2.3 2.9    2.8        2^  sellation.    The 

eggs  are  probably  less  than  twice  as  long  as 
wide.  Each  of  the  12  rather  conspicuous, 
echinulate,  mammiform  accessory  organs  is 
situated  on  the  posterior  side  of  a  transverse 
ceratinous  ridge  extending  one-fourth  the  dis- 
tance around  the  body.  The  anterior  two  or 
three  and  the  posterior  one  of  these  organs 
are  smaller  than  the  others.  There  are  2  pairs 
of  ventrally  submedian  papillae,  also  inner- 
vated, on  the  anterior  third  of  the  tail,  the 
posterior  pair  being  near  the  end  of  the  an- 
terior third,  and  the  other  pair  half  way  be- 
tween- that  point  and  the  anus.  There  are 
other  papillae  faintly  visible  on  the  dorsal  side 
of  the  tail  and  elsewhere  (fig.  16).  The  fe- 
males of  this  species  also  present  papillae  near  the  vulva:  3  small,  ventrally 
submedian  papillae  on  each  side  of  the  body,  one  opposite  the  vulva,  one  a  short 
distance  in  front  of  it  and  another  a  short  distance  behind  it,  and  in  addition  a 
tandem  series  of  3  papillae,  both  in  front  of  and  behind  the  vulva,  on  the  ventral 
line.  The  location  and  conformation  of  these  papillae  is  shown  in  figure  12.  Doubt- 
less the  females  of  other  species  possess  similar  papillae.  Fixed  with  osmic  acid; 
examined  in  water. 

Found  about  the  roots  of  plants,  in  damp  soil,  Moss  Vale,  New  South  Wales, 
Australia.  Also  about  turnips  in  Tasmania.  This  species  resembles  the  following. 
Fig.  25. 

12.  M.  gerlachei  de  Man.  Lateral  fields  about  one-third  as  wide  as  the  body. 
In  transverse  section  the  buccal  cavity,  though  nearly  round,  is  obscurely  three- 
sided,  and  shows  the  existence  of  3  small,  longitudinal  grooves  in  the  wall  of  the 
2.  5.2  18.  '50'33  92.5  _ 


1.8 
2. 


2. 
95.5 


1.8       ?  ?  3.7          2.3 

pharynx,  presumably  so  functioning  as 

to  increase  the  elasticity  and  mobility  of 

the  pharyngeal  walls.     What  appears  to 

be   a    renette    pore    occurs    immediately 

behind    the    nerve-ring.      Anal    muscles 

are  well  developed  in  the  female.    Spic- 

ula  arcuate,   tapering  both  ways,   about 

one  and  one-third  times  as  long  as  the 

anal  body-diameter,  and  in  their  widest 

part    about    one-sixth    as    wide    as    the 

corresponding  portion  of  the  body.   The 

accessory  pieces  are  about  one-third  as  long  as  the  spicula,  relatively  small  and 

poorly  developed,  appearing  to  be  parallel  to  them  when  viewed  in  profile.     The 


15g(S.S.460)  THE   M  ON  ON  CHS 

pre-anal  ventral  row  of  supplementary  organs  is  essentially  the  same  as  in  major 
(fig.  16).  According  to  Steiner's  observations  the  number  of  supplementary  organs 
in  this  species  may  at  times  be  as  great  as  that  noted  in  major.  Steiner  calls  atten- 
tion to  the  existence  of  a  submedian  row  t>£  pre-anal  papillae,  lying  on  either  side 
of  the  ventral  row.  The  tail  bears  3  pairs  of  papillae,  one  submedian  or  subventral 
pair  near  the  anus ;  a  second  subventral  pair  slightly  behind  the  middle ;  and  a  third 
dorsally  submedian  pair  at  the  beginning  of  the  final  fourth  of  the  tail.  In  the 
male  the  slightly  conoid  spinneret  is  one-sixth  to  one-seventh  as  wide  as  the  base  of 
the  arcuate  tail.  The  proportions  are  about  the  same  as  in  the  female,  although  the 
tail  of  the  female  is  slightly  longer  and  more  slender,  and  not  so  strongly  arcuate. 
Found  among  fresh  water  algae,  Cape  Van  Beneden,  Banco  Land.  It  is  rather 
difficult  to  point  out  satisfactory  differences  between  this  species  and  major.  The 
pharynx  of  gerlachei  is  relatively  smaller  and  is  thicker  walled,  and  its  dorsal  tooth 
is  slightly  farther  forward.  The  number  of  labial  papillae — sixteen — appears  to  be 
the  same  in  each.  The  amphids  are  perhaps  slightly  farther  back  in  major  than 
in  gerlachei.  The  number  of  papillae  noted  on  the  tail  of  the  male  of  major  is 
greater  than  that  noted  on  the  tail  of  gerlachei,  but  so  far  as  the  distribution  of 
the  dorsal  papillae  on  the  tail  of  gerlachei  is  concerned,  they  appear  to  accord  very 
closely  with  those  of  major.  The  two  species  appear  to  be  closely  related.  Fig.  26 
on  the  previous  page  (after  de  Man). 

13.  M.  fovearum   (Dujardin)   Bastian.     This  is  an  insufficiently  known  species 
and  may  have  to  be  declared  nomen  nudum.     Head  a  trifle  angular.     Pharynx 
angular,  "armed  with  2  to  3  straight  pieces,  each        ?      ?      is.      ^50'      93.      2  5  „,„ 
(?)    with    a   pronounced   tooth   in   front   of   the       ?  -  ?       ?  3.        ? 
middle."     Tail  tapering  at  first  but  retaining  the  same  diameter  through  its  pos- 
terior half,  and  ending  in  a  sort  of  spinneret  (?).    Eggs  in  single  series. 

Found  at  Rennes,  France,  in  a  fresh  water  ditch,  along  with  Branchipus,  ento- 
mostrica,  Eitglena  etc.    De  Man  suggests  that  this  species  is  related  to  tridentatus. 

14.  M.  megalairnus,  n.  sp.    Labial  papillae  obscure.    Amphids  obscure,  half  way 
between  the  apex  of  the  dorsal  tooth  and  the  anterior  extremity.    Cardia  large  and 

2.9      9.      28,.     '•s:?'38    86.  conspicuous,    more    or 

1-8      2-6      3-1       3-5       I-7  '     less    cylindroid,    three- 

fourths  as  wide  as  the  body.  Intestine  about  12  cells  in 
girth,  more  or  less  distinctly  tessellated.  At  the  end  of 
the  anterior  third  the  tail  is  one-fourth  as  wide  as  at 
the  anus.  Spinneret  slightly  swollen,  with  2  very  small  digi- 
tate setae. 

About  the  roots  of  plants,  in  a  tamarack  swamp,  Wisconsin, 
\J.  S.  A.  This  mononch  is  peculiar  in  the  relatively  meager 
development  of  the  labial  papillae  and  the  pharyngeal  teeth, 
and  the  weakness  of  the  pharyngeal  muscles.  Flemming  solu- 
tion to  glycerine.  Fig.  27. 
15.  M.  macrostoma  Bastian.  Inner  set  of  labial  papillae  inconspicuous;  outer 
set  fairly  well  developed.  The  neck  tapers  but  little.  The  head,  however,  is  rather 
markedly  convex-conoid.  De  Man  describes  and  figures  2  exceedingly  minute 
submedian  teeth  at  the  base  of  the  pharynx.  CEsophageal  lining  strongly  devel- 
oped. Intestine  12  to  15  cells  in  girth,  tessellated.  Posterior  half  or  two-thirds  of 
the  tail  of  the  female  of  practically  uniform  diameter,  tapering  but  very  slightly. 
Spicula  arcuate,  very  slender,  about  twice  as  long  as  the  anal  body-diameter.  Their 
proximal  ends  are  not  cephalated.  They  are  accompanied  by  2  accessory  pieces, 
hardly  one-third  as  long,  arranged  parallel  to  their  distal  parts.  Supplementary 
organs,  about  20,  in  the  form  of  innervated  papillae,  spread  over  a  distance  nearly 


SUBGENUS  MONONCHUS 


(S.  s.461)  159 


equal  to  the  length  of  the  tail,  the  posterior  member  of  the  series  being  a  short 
distance  in  front  of  the  anus.  There  are  3  pairs  of  somewhat  equidistant  subven- 
tral  post-anal  papillae  on  the  anterior  part  of  the  tail.  There  are  also  lateral 
papillae  on  the  tail. 

This  beautiful,  ac-      ^    ^6    *°| '•&£ — *|^  2-  M      ^-7^-7-^^  _ ^ 

tive,  rather  common  2  6  ?  25  M  92 
species  is  found  in  ?  ? ^  ? T~~^  ll8  BB 
the  soils  of  meadows  and  marshes  in  many  parts  of 
Europe ;  it  is  also  aquatic.  The  writer  has  followed 
Dr.  de  Man's  rehabilitation  of  Bastian's  macrostoma. 
Corresponding  females  which  the  writer  has  found  at 
the  Arlington  Farm,  Virginia,  U.  S.  A.,  indicate  the 
presence  of  exceedingly  fine  transverse  striae,  and  of  in- 
conspicuous wings.  Amphids  obscure,  just  behind  the 
lips,  difficult  to  see  except  in  dorso-ventral  view.  The 
oesophagus  receives  the  basal  fourth  of  the  pharynx, 
and  in  this  region  is  very  slightly  swollen.  The  writer 
failed  to  see  the  minute  basal  onchi  mentioned  by  de  Man.  The  thin-shelled  eggs, 
which  occur  in  the  uteri  one  at  a  time,  are  about  one  and  one-fourth  times  as  long 
as  the  body  is  wide  and  about  half  as  wide  as  long,  and  are  apparently  deposited 
before  segmentation  begins.  The  writer  has  no  doubt  this  species  is  syngonic.  A 
female  which  had  yet  to  undergo  the  final  moult  contained  an  egg  which  had  its 
shell  completely  formed,  and  was  evidently  in  a  state  preparatory  to  segmentation. 
Flemming  solution  to  glycerine.  Fig.  28  (after  de  Man). 

According  to  Bastian -the  following  differences  exist  between  macrostoma  and 
truncatus;  macrostoma  is  50  per  cent  longer,  and  is  relatively  narrower  in  the  ratio 
of  3.5  to  5.3.  Macrostoma  tapers  less  in  the  neck,  and  has  papillae,  while  truncatus 
has  none.  While  macrostoma  is  the  larger,  its  pharynx  is  no  longer ;  the  onchus  is 
a  little  farther  forward.  The  intestine  in  macrostoma  is  less  distinctly  tessellated. 
The  posterior  part  of  the  oesophagus  in  macrostoma  is  figured  as  having  an  internal 
expansion.  These  characters  seem  to  the  writer  sufficient  to  separate  the  two 
species.  It  is  probable  that  papillae  on  the  head  of  truncatus  were  overlooked  by 
Bastian.  This  would  have  been  easy,  for  instance,  if  the  papillae  on  truncatus  are 
similar  to  those  on  megalaimus.  See  figure  27. 

16.     M.  obtusus,   n.    sp.     Papillae   setose.     The  adjacent  figure    (29)    is   after 
2.4      •>      25.      ^50+^      87.  Biitschli,   whose 

275  ?  472  ?  3.3  1-7  "  figures  seem  to 
represent  a  different  species  from  that  figured  by  de 
Man  under  the  name  macrostoma,  notwithstanding  the 
general  resemblances.  The  proportions  of  the  tail  and 
of  the  spicula  are  different  in  the  two  forms;  the  dis- 
tribution of  the  papillae  on  the  tail  is  also  different,  and, 
while  the  number  and  position  of  the  pre-anal  ventral 
supplementary  organs  are  about  the  same,  their  form  as 
shown  by  Biitschli  is  decidedly  different  from  that 
shown  by  de  Man.  In  addition,  Biitschli's  figure  shows 
3  pairs  of  pre-anal,  ventrally  submedian  papillae  coex- 
tensive with  the  ventral  row.  Biitschli's  data  may  there- 
fore, the  writer  thinks,  be  taken  as  establishing  this  new 
species.  Synonym,  M.  truncatus  Bastian  of  Biitschli. 
Found  in  the  River  Main,  Germany ;  common  in  mud 
and  in  aquaria  and  among  aquatic  plants,  in  moving  water  not  foul.  See  also  fig.  15. 


1(30  (S.  S.  462) 


THE   MONONCHS 


17.  M.  tunbridgensis  Bastian.  The  Tunbridge  mononch  is  interesting  histori- 
cally as  well  as  intrinsically,  for  it  was  an  examination  of  numerous  specimens  of 
this  aquatic  nema  that  marked  the  beginning  of  the  classical  researches  of  the 

6.7       24.          '52'20 


2.4 
2.1 
2.4 


2.8 

7.8 


24. 

3.6 
23. 


3.7 


89. 
2.3    - 

90. 


1.3  n 


2.          3.5          ?.6         ?.7  1.7 

well-known  English  nematologist,  H. 
Charlton  Bastian.  The  upper  formula 
is  the  average  of  glycerine  specimens 
from  the  Arlington  Farm,  Virginia, 
U.  S.  A.,  while  the  lower  formula  is 
the  average  of  the  writer's  balsam 
specimens  from  Tunbridge  Wells,  Eng- 
land. As  a  rule  the  4iead  is  rather  suddenly  contracted  opposite  the  pharynx,  and 
this  is  perhaps  the  best  distinguishing  mark  of  the  species.  Bastian,  who  had  an 
abundance  of  specimens,  emphasizes  this  character.  The  adjacent  figures  are  those 
of  Dr.  de  Man,  and  show  the  pharynx  relatively  a  little  narrower  than  is  usual.  The 
tails  of  the  writer's  Tunbridge  Wells  specimens  accord  rather  with  Bastian's  figure 
than  with  his  description.  As  is  often  the  case  in  other  mononchs,  the  labial  papillae 
stain  more  strongly  with  carmine  than  do  adjacent  tissues,  so  that  the  lip  region  as 
a  whole  appears  strongly  colored.  Opposite  the  dorsal  tooth  there  is  an  exceed- 
ingly minute,  low,  subventral  projection.  The  form  of  the  amphids  is  not  fully 
determined ;  they  are  located  nearly  opposite  the  base  of  the  pharyngeal  tooth,  and 
have  a  width  one-half  to  one-third  as  great  as  that  of  the  pharyngeal  cavity.  Near 
the  cardia  the  cesophageal  lining  occupies  about  one-fourth  of  the  optical  longitudi- 
nal section  of  the  oesophagus.  The  intestine,  which  ma}'  present  a  certain  amount 
of  tessellation,  is  about  10  to  12  cells  in  girth.  The  anterior  two-fifths  to  one-half 
of  the  tail  is  conoid  in  such  a  fashion  that  at  the  middle  the  diameter  is  about 
one-sixth  as  great  as  at  the  anus.  Thence  onward  the  tail  is  nearly  cylindrical,  and 
ends  in  a  very  slightly  expanded  terminus  armed  with  one  or  two  very  inconspicuous 
papillae.  That  a  sticky  substance  often  exists  on  the  surface  of  the  terminus  of  the 
tail  is  evident  from  the  accumulation  there  of  minute  particles  of  foreign  matter. 
Caudal  glands  appear  to  exist  immediately  behind  the  anus,  but  their  nuclei  have 
not  been  definitely  made  out  as  yet.  The  lateral  fields  appear  to  be  one-third  as 
wide  as  the  body.  Each  ovary  contains  a  score  or  more  of  developing  ova,  ar- 
ranged in  several  tiers  in  the  distal  half  of  the  organ,  but  single  file  elsewhere. 
The  somewhat  elongated  eggs  are  about  one  and  one-third  times  as  long  as  the 
body  is  wide,  and  about  half  as  wide  as  long,  and  occur  in  the  uteri  one  at  a  time. 
This  seems  to  be  primarily  an  aquatic  species,  though  the  writer  has  found  it  also 
in  soil  in  the  vicinity  of  rivers  and  streams.  Fig.  30  (after  de  Man). 
18.  M.  truncatus  Bastian.  CEsophagus  conoid,  its  lining  well  developed.  Intes- 
2.5  ?  25.  '50+*  86.  tine  about  12  cells 

?       if; sTa       3.4  '  1-8  BB        in   girth,   more   or 
?      25.      M      92.\   „  less  distinctly  tes- 

?       ?       ?       ?    '  sellated.     Lateral 

fields  broad  and  distinct.  It  is  a  question  whether  to 
retain  this  species  on  the  basis  of  Bastian's  original 
description,  or  to  accept  Biitschli's  description  as  a 
rehabilitation  of  Bastian's  species.  It  is  hardly  likely 
that  any  species  of  Mononchus  is  destitute  of  labial 
papillae,  and  in  this  respect  Bastian's  description 
seems  defective.  The  extreme  reduction  of  the 


SUBGENUS  MONONCHUS 


labial  papillae  so  far  recorded  is  shown  in  megalaimus.  Biitschli  and  later  authors 
describe  and  figure  the  papillae  of  truncatus  as  setose.  It  seems  hardly  likely  that 
Bastian  would  have  overlooked  setose  papillae  such  as  those  figured  by  Biitschli. 
In  that  case  Bastian's  truncatus  should  be  retained  as  a  species,  probably  having 
very  inconspicuous  labial  papillae  similar  to  those  of  megalaimus,  while  the  data 
given  by  Biitschli  may  be  taken  as  establishing  a  new  species,  for  which  the  name 
obtusus  is  proposed.  (See  No.  16.) 

Found  in  a  small  pool,  among  decaying  moss  and  liverwort,  England.     Fig.  31 
(after  Bastian). 

19.  M.  dadayi  Micoletzky.    A  striking  character  of  this  species,  "M.  macrostoma 
Bastian  var.  armatus  Daday,"  as  described  by  its  author,  is  the  presence  of  6  small, 

?      ?      22.      ?      86.  tooth-like  cuticular  spines  close 

H1  ?  ?  ?  4~72 2.6  K6  '"  around  the  mouth.  No  such 
structures  have  been  seen  in  other  species,  and  accordingly 
Micoletzky  has  proposed  for  the  form  the  name  dadayi. 

This  is  a  littoral  species.     The  description  and  drawings 
rest  upon  the  examination  of  a  single  specimen.    The  original 
,m   description  is  very  brief  and  the  accompanying  illustrations, 
one  of  which  is  here  reproduced,  are  meager  sketches  of  the 
head  and  tail  ends.    A  more  complete  examination  of  further 
750   specimens  is  desirable.    Fig.  32  (after  Daday). 

20.  M.  longicaudatus  Cobb.     Opposite  the  apex  of  the  dorsal  tooth  there  are 
refractive  transverse  thickenings  of  the  wall  of  the  pharynx  in  the  ventrally  sub- 
median  region,  and  in  front  of  these  thickenings  there  are  a  few  transverse  striae. 
The  lateral  fields  are  two-fifths  as  wide  as  the  body,  and  are  distinctly  to  be  seen, 
since  they  have  definite  lateral  contours,  doubtless  owing  to  the  thickness  of  the 
muscular    layer.      The   lateral    fields    contain    scattered,    nearly   colorless    granules 
somewhat  smaller  than  those  contained  in  the  intestinal  cells.     In  young  specimens 
the  vagina  is  distinctly  separated  from  the  uterus  by  a  deep  constriction,  and  the 
uterus  itself  is  bulbous  near  this  constriction  and  narrower  farther  away.     Longi- 
caudatus   is    a    syn-     3.      6.?      26.       ^55*23      88. 

gonic     species.       In     2~! 274       3~l 3~! 2.4        ' 
the  adult  and   egg-producing  specimens  the   eggs   are 
seldom  or  never  seen  more  than  two  at  a  time,  one  in 
each  uterus. 

A  predacious  species,  feeding  upon  other  nematodes, 
upon  rotifers  and  protozoa.  It  is  cosmopolitan,  and  is 
found  in  rivers,  ditches  and  pools,  as  well  as  in  the 
soils  of  swamps  and  meadows.  It  occurs,  sometimes  in 
vast  numbers,  in  the  sand  of  the  slow  filter  beds  of  the 
water-works  of  cities  and  towns.  Flemming  solution 
to  glycerine.  Fig.  33 ;  also  fig.  2,  p.  132. 

Longicaudatus  suffers  from  an  internal  disease  caused 
by  a  fungus  having  a  branched  mycelium.  The  width 
of  the  mycelium  is  about  half  as  great  as  the  thickness  of  the  body  wall  of  the 
nema,  and  the  septa  oi  the  cells  are  separated  from  each  other  by  a  distance  equal 
to  the  diameter  of  the  body.  There  are  two  other  diseases  affecting  this  nema, 
one  of  microbe  origin,  the  other  of  fungous  origin;  they  appear,  however,  to  be 
confined  to  the  cuticle.  One  consists  of  short-styled,  elongated-ellipsoidal  elements 
on  the  surface  of  the  body  extending  outward  at  right  angles.  These  have  been 
seen  on  the  tail  end.  The  microbe  growth  appears  as  a  coating,  sometimes  of 
considerable  thickness,  and  occurs  on  various  parts  of  the  body.  It  has  been  seen 


ff/OW 


.  464) 


THE   MONONCHS 


at  both  extremities.  The  adjacent  figure  (34)  depicts  the  tail  end  of  a  male  found 
in  Hawaii  about  the  roots  of  sugar-cane.  The  general  resemblance  to  the  male  as- 
signed by  Biitschli  to  M.  truncatus  Bastian  is  very  striking,  yet 
the  differences  in  detail  are  also  pronounced.  The  number  of 
supplementary  organs  is  16  instead  of  about  20,  and  the  organs 
themselves  relatively  shorter  and  more  plump.  The  spicula  and 
their  accessory  pieces  have  the  same  general  proportions  and  size. 
The  tail  also  has  the  same  form  and  proportions,  but  the  termi- 
nal portion  is  more  slender  in  the  Hawaiian  specimen,  and  the 
distribution  of  the  papillae  thereon  is  decidedly  different,  as  will 
be  seen  by  comparing  figures  15  and  34.  Male  mononchs  are  so 
rare  that  the  amount  of  variation  that  may  exist  in  a  given 
species  is  a  nearly  unknown  quantity,  so  that  it  is  not  exactly 
easy  to  make  intelligent  comparisons  between  the  males  in 
these  two  cases.  The  Hawaiian  male  is  supposed  to  be  the 
male  of  M.  longicaudatus,  the  only  one  that  has  ever  been 
seen.  It  is  interesting  to  note  that  when  the  spicula  become 
long  and  slender  the  accessory  pieces  also  become  long  and 
slender,  but  maintain  their  general  form  and  are  bifurcated  at 
the  distal  end.  Fig.  33  (on  the  previous  page)  and  fig.  34.  It  is 
a  curious  fact  that  this,  the  only  male  of  M.  longicaudatus 
ever  seen  among  the  many  thousands  examined,  should  have 
come  from  soil,  since  longicaudatus  is  much  less  common  in 
soil  than  in  water. 

2ia.    M.  dentatus,  n.  sp.     This  representative  of  a  new  subgenus  is  especially 
interesting  as  a  guide  to  speculation  concerning  the  relationship  of  Mononchus  to 


27.        '62'14     95. 


1.1  mm 


3.6       2.8         3.3         3.3         1.9 

other  genera.  The  scattered  denticles  are 
paralleled  in  certain  marine  nemas.  The 
arcuate  tail  is  conoid  from  the  raised  anus. 
The  rather  blunt  terminus  is  about  one- 
fourth  as  wide  as  the  base  of  the  tail.  There 
is  a  pair  of  ventrally  submedian,  innervated 
papillae  a  little  in  front  of  the  middle  of 
the  tail.  The  amphid  is  sometimes  more  elongated  than  shown  in  the  illustrations. 
Description  of  a  young  female,  from  roots  of  orange  trees,  Bahia,  Brazil.  Fig.  35. 
For  21b,  M.  recessus,  and  21c,  M.  decurrens,  see  Appendix,  p.  184. 

22.     M.  punctatus,  n.  sp.     This  species  is  proposed  for  the  reception  of  the 

specimen  described  by  Brakenhoff  under  the  name  M.  papillatus  Bastian,  which 

appears  to  differ  from        2.6      ?      25.      »65'26      93. 

any   mononch    hitherto       ^2      ?       ?          3~75 ? 

described  in  that  the  shells  of 
the  eggs  are  echinulate.  It  is 
placed  in  the  subgenus  Pri- 
onchulus,  though  with  some 
doubt,  principally  because  both 
the  description  and  the  figure 
of  Brakenhoff  show  the  pres- 
ence of  denticles  on  the  ven- 
tral rib  of  the  pharynx.  The 
author  says:  "Hier  findet  sich 
namlich  cine,  in  der  Mitte  (und  an  den  2  Seiten)  fein  gezahnelte  Leiste.  Diese 


SUBGENUS  PRIONCHULUS 


(S.  S.  465)  163 


Zahnelung  erstreckt  sich  iiber  eine  etwa  0.016  mm.  lange  Strecke  und  beginnt 
distalwarts  etwa  in  der  Hohe  der  Spitze  des  dorsalen  Zahns."  The  ellipsoidal 
eggs  occur  in  the  uteri  one  at  a  time,  are  about  as  long  as  the  body  is  wide,  and 
two-thirds  as  wide  as  long. 

Found  among  the  roots  of  Alopecurus  denticulatus ,  as  well  as  aquatic  habitats 
in  the  bottom  of  ditches  and  lakes  in  Germany.   Fig.  36  and  36a  (after  Brakenhoff)' 

23.  M.  muscorum  (Dujardin)  Bastian.  The  oldest,  and  one  of  the  best  known 
species.  Intestine  tessellated.  Tail  conoid  and  arcuate.  The  reflexed  ovaries,  each 
containing  about  a  dozen  ova  arranged 
more  or  less  in  single  file,  extend  half  way 


fpl 


mrpt 


2. 


24. 


;,32 


2.5-3. 


92. 


1.9  rain 


2.1      2.7       3.2          3.6  1.6  2.          3.2         3.7          4.4  2.5 

back  to  the  projecting  vulva.  The  eggs  are  one  and  one-half  times  as  long  as  the 
body  is  wide  and  three-fourths  as  wide  as  long.  The  anterior  sexual  organ  is 
somewhat  the  larger.  Fig.  37,  left. 

This  is  a  beautiful  and  rather  common  cosmopolitan  species,  occurring  in  swamps, 
marshes,  meadows  and  moorlands.  It  has  been  found  in  various  parts  of  Europe 
and  is  not  uncommon  in  the  United  States.  It  was  first  found  by  DujardinWn  the 
Jardin  des  Plantes,  Paris,  where  it  still  thrives ;  the  writer  recently  found  it  about 
the  roots  of  some  heather  imported  thence.  It  feeds  on  smaller  animal  organisms, 
among  them  other  nematodes.  The  following  is  a  variety : 

M.  muscorum  (Dujardin)  Bastian  macrolaimus,  n.  var.  Besides  differing  slightly 
in  proportions  from  the  type  form  of  the  species,  the  variety  has  a  somewhat  larger 
pharynx,  with  smaller  denticles  on  the  ventral  rib.  The  submedian  papillae  of  the 
outer  sets  are  apparently  double  instead  of  triple,  though  at 
some  distance  behind  the  outer  submedian  papillae  there  is  a 
special  submedian  innervation.  Most  of  these  minor  differences 
are  set  forth  in  figures  36  and  37. 

Found  in  Cladonia  rangiferina,  tamarack  swamp,  Wisconsin,    m 
U.  S.  A.    Fig.  38,  right. 

24.     M.  longicollis,  n.   sp.     A  species  resembling  M.  mus- 
corum, but  which  differs  in  the  proportions  of  the  various  parts    *"- 
and  in  the  conformation  of 


m  ikl 


3.1 


10.        27. 


93. 


the   pharynx,    the    denticles    2.2        2.4      2.3    2.1     1.8      i>£  "" 
of  which  are  irregular  and  inward  pointing.     Submedian  papil- 
lae of  the  outer  row  double,  instead  of  triple  as  in  muscorum.     Amphids  relatively 


154  (S-  S.  466) 


THE  MONONCHS 


? 

20. 


? 
M       ? 


-  3.6  an 


larger  than  in  muscorum.  Striae  very  difficult  of  resolution.  Found  about  the 
roots  of  pitcher-plants  and  tamarack,  in  a  swamp,  Wisconsin,  U.  S.  A.  The  differ- 
ence between  this  and  muscorum  may  not  be  very  important.  Both  are  nema- 
tivorous.  Flemming  mixture  to  glycerine.  Fig  39  (at  bottom  previous  page). 

25.  M.  spectabilis  Ditlevsen.    The  muscular  oesophagus  encompasses  the  proxi- 
mal third  of  the  pharynx,  and  has  a  conspicuous  lining.     The  uteri  may  contain 

?  ?  20.  '55'  96.8  ,  __  from  2  to  4  eggs, 
usually  2.  The 
acute  conical  tail 

?        ?      ?  is    strongly    arcu- 

ate. The  male  is  a  little  more  slender  than 
the  female,  and  increases  in  size  from  a  point 
where  the  supplementary  organs  commence,  in 
such  a  way  that  the  body  assumes  a  maximum 
circumference  near  the  anus.  The  copulatory 
muscles  are  strongly  developed,  and  the  num- 
erous, prominent,  supplementary  organs  appear 
to  have  a  subventral  position,  forming  two 
longitudinal  rows,  between  which  is  a  groove. 
Fourteen  of  these  supplementary  organs  are 
figured  by  Ditlevsen — manifestly  not  the  whole 
series.  The  arcuate  spicula,  which  have  a 
strengthening  piece  in  their  distal  halves,  are 
about  one  and  one-half  times  as  long  as  the 
anal  body-diameter.  Their  proximal  ends  are 
not  cephalated.  At  the  widest  part,  toward 
the  proximal  end,  they  are  about  one-fifth  to  one-sixth  as  wide  as  the  body ;  thence 
toward  the  distal  end  they  taper  gently.  The  obscurely  bifurcated  accessory  pieces, 
which  in  profile  view  appear  to  cross  the  spicula,  are  of  the  usual  form,  and  are 
about  one-third  as  long  as  the  spicula,  and  about  one-third  to  one-fourth  as  wide  as 
long.  Their  distal  extremities  lie  somewhat  in  front  of  the  tips  of  the  spicula  and 
toward  the  ventral  side  of  the  body.  The  elongated  eggs  are  nearly  one  and  one- 
half  times  as  long  as  the  body  is  wide,  and  less  than  half  as  wide  as  long. 

Numerous  specimens,  the  males  as  numerous  as  the  females,  found  at  Hellerup, 
near  Oresund,  Denmark.  This  species  exhibits  the  phenomenon  of  flotation.  Dit- 
levsen says :  "If  some  material  (meadow  soil)  is  spread  in  a  flat  glass  cup  and 
water  is  poured  over  it,  the  mononchs  will  mount  rapidly  and  be  lying  on  the  sur- 
face dry  and  shining."  Fig.  40  (after  Ditlevsen). 

26.  M.  index  Cobb.    No  striae  seen.    The  .neck  diminishes  opposite  the  base  of 
the  pharynx  to  form  a  rather  cylindrical,  truncated  head  which  is  slightly  expanded 
at  the  lip  region.    Amphids,  one-fifth  as  wide     2.1      8.8      30.      *6915      95. 6  N 

as  the  head,  are  indicated  by  transverse  mark-  2.4  3.2  3.5  3.6  2. 
ings,  bent  backward  at  each  end,  and  located  opposite  the  middle  of  the  dorsal 
tooth.  Denticles  in  about  five  rows,  the  outer  rows  more  distinct.  Pharynx  half 
as  wide  as  the  head,  and  about  three  times  as  deep  as  wide.  CEsophagus  more  or 
less  conoid,  with  a  massive  lining  occupying  about  one  fourth  of  the  optical  sec- 
tion. Cardia  pointed.  Intestine  few  cells  in  girth;  rather  obscurely  tessellated. 
Rectum  half  as  long  as  the  anal  body-diameter.  Longitudinal  fields  are  visible 
throughout  most  of  the  length,  and  are  about  two-fifths  as  wide  as  the  body.  The 
diameter  of  the  body  increases  somewhat  just  in  front  of  the  anus,  and  then  dimin- 
ishes suddenly  at  the  anus,  so  that  the  beginning  of  the  tail  is  very  considerably 
less  in  diameter  than  the  portion  of  the  body  immediately  in  front  of  the  anus. 


SUBGENUS  MYLONCHULUS 


(S.s.467) 


The  diameter  of  the  cylindrical  portion  of  the  tail  is  about  one-fourth  that  of  the 
body  at  the  anus.  Caudal  glands  3,  egg-shaped,  opposite  the  anus.  Spinneret 
slightly  apiculate  and  apparently  unarmed.  The  eggs  are  evidently  of  large  size. 
A  single  egg,  not  yet  passed  on  to  the  uterus,  was  four-fifths  to  five-sixths  as  wide 
as  the  body,  and  about  three  times  as  long  as  wide. 

Common  about  the  roots  of  sugar  cane  on  various  plantations  on  the  island  of 
Hawaii.  Flemming  solution  to  glycerine. 

27.  M.  reversus,  n.  sp.     This  very  interesting  abnormal  form  possesses  striae 
that  appear  resolvable  into  rows  of  dots.     Intestine  about  6  cells  in  girth,  faintly 
tessellated.     Tail  more  or    2       94      26       40'  1?      96 

less  cylindroid  in  the  pos-  2.2  2.3  27?  §74  2.  **  l>1  n 
terior  half,  its  terminus  one-fourth  to  one-fifth  as  wide  as 
its  base.  Lateral  fields  two-fifths  as  wide  as  the  body.  The 
eggs  are  of  relatively  large  size,  since  an  ovum  not  yet 
passed  on  to  the  uterus  is  5  to  6  times  as  long  as  the  body  is 
wide.  It  is  therefore  likely  that  the  eggs  occur  in  the  uterus 
only  one  at  a  time.  The  relatively  broad  ovary  tapers  but 
little;  it  contains  about  a  dozen  developing  ova. 

Rio  Janiero,  Brazil,  about  the  roots  of  Platonia  insignis  Mart.  In  general  this 
species  resembles  incurvus  and  minor,  but  is  readily  distinguishable  by  the  form  of 
the  sexual  organ,  and  by  the  sparseness  of  the  pharyngeal  denticles,  only  a  few  of 
which  are  to  be  seen.  When  the  female  sexual  organs  reduce  to  one,  this  remain- 
ing one  usually  extends  forward  from  the  vulva.  Here  the  reverse  is  the  case; 
hence  the  specific  name.  Flemming  solution  to  glycerine.  Fig.  41. 

28.  M.  obtusicaudatus  Daday.     Tail  conoid,  slightly  arcuate;  toward  the  end 

rather     suddenly     di- 
#-  ------  ........  -~-V\       /N  ^      7     M-  _  1?Z!_JL1^1<9  M  minished  in  size.  The 

spinneret  well  marked. 

Found  at  Berlinhaven,  Island  of  Salao,  New 
Guinea,  in  fresh  water.  It  seems  probable 
from  Daday's  description  that  there  are  3 
teeth  in  the  pharynx,  1  dorsal  and  2  smaller 
submedian  ones  just  at  the  base  of  the  rasps. 
Probably  fhe  junction  between  the  posterior 
and  anterior  elements  of  the  pharyngeal  walls 
is  unusually  prominent  ;  this  would  account  for 
the  "bogige  leiste"  mentioned  in  the  original 
description  and  shown  in  the  original  figure 
along  the  anterior  margin  of  the  rasp.  Fig. 
42  (after  Daday).  Assuming  Daday's  drawing 
to  be  more  or  less  conventionalized,  this  species 
might  be  regarded  as  identical  with  minor. 

29.  M.  brachyuris  Biitschli.     Amphids  appear  as  transverse  slits  opposite  the 
onchus.     Lining  of  the  oesophagus  strongly  developed.     Cardia  plainly  to  be  seen. 


28. 


'62 


18 


96. 


Intestine  tessellated.    2.2 

Rectum  half  as  long    274      i79      371        379         2.2 

as  the  anal  body-diameter.     Caudal  glands  more  or  less 

saccate,   opposite  the  somewhat  raised  anus.     Tail  some- 

what arcuate.     Spinneret  pore  a  little  to  the  dorsal  side  of 

the  middle  of  the  terminus.     The  vulva  is  a  conspicuous 

feature,  owing  to  the  thickness  of  the  walls  of  the  vagina, 

which  is  one-half  as  long  as  the  body-diameter.     Series  of 


166  (S.  S.  468) 


THE  MONONCHS 


male  supplementary  organs,  according  to  de  Man,  about  12,  mammiform  and  appar- 
ently protrudable  except  the  two  anterior  and  the  posterior,  which  are  more  or  less 
rudimentary.  Series  about  twice  as  long  as  the  tail. 

A  cosmopolitan  species.    In  Florida,  the  writer  found  this  species  feeding  on  the 
larvae  of  Heterodera  radicicola,  an  extremely  serious  root  pest.   Fig.  43,  bottom  p.  467. 
30.     M.  denticulatus,   n.  sp.     Onchus  opposed  by  two  small  subventral  onchi 
farther  back,  the  left  a  little  farther  forward  than  the  right 
Found  in  the  Zambezi  River,  South  Africa,  among  fresh 
water  algae.     The  peculiar  form  of  the  head  and  pharynx, 
and  the  unusually  large  number  of  denticles  are  the  promi- 
nent characters  of  this  species.     Only  a  single  mutilated 
specimen  has  been  seen  by  Dr.  Micoletzky.     As  it  is  un- 
likely  that  the  large  number   of   denticles   shown   in  the 
original    figures    can   be   due   to    moulting   phenomena,    it 
would  seem  that  this  form  differs  distinctly  from  all  others. 
Fig.  44  (after  Micoletzky).     As  neither  Micoletzky's  text 
nor  figure  suggests  moulting,  the  numerous  rows  of  den- 
ticles are  assumed  to  be  normal, 
sp.     Each  rasp  consisting  of  but  2  rows  of  denticles.     The 

12.        32.        54Y       94. 


31.     M.  sparsus,  n. 

tail  diminishes  suddenly  in  size  2.9 
behind  the  elevated  anus,  and  3.4 


4.3        4.2        3.8       2^7^ 

tapers  somewhat  in  the  posterior  three-fourths.  The  terminus 
is  about  one-fourth  as  wide  as  the  base  of  the  tail.  The  cau- 
dal glands  (?)  lie  opposite  the  rectum. 

Found  in  sphagnum  from  greenhouses,  Department  of  Agricul- 
ture, Washington,  D.  C.,  U.  S.  A.  Flemming  solution  to  glycer- 
ine. Fig.  45. 

32.  M.  micrurus,  n.  sp.  This  odd  form  appears  to  have  no  submedian  onchi. 
Rasps  of  only  about  four  rows  of  denticles.  Amphids  not  seen.  Lining  of  the 
esophagus  well-developed,  occupying  three-fifths  of  the  optical  longitudinal  section. 
3.  12.  33.  Y  98.  Intestine  about  5  cells  in  girth, 

27?      37i      3.7    3.        2.2  not  tessellated,  or  only  faintly 

so.     Tail  very   short  and  strongly   arcuate  or  bent.      Spinneret 
about  one-fifth  as  wide  as  the  base  of  the  tail.     Rectum  some- 


what  shorter  than  the  anal  body-diameter;  longer  than  the  tail. 

Caudal   glands  not  clearly  seen,   probably   opposite  the  rectum. 

Ampullae  of  the  caudal  glands  not  very  strongly  developed. 
Described    from   young   specimens    found   about  Litchi   roots, 

Fukien,  China.     Resembles  bremcaudatus.     Characterized  by  the 
extremely  small  and  very  strongly  arcuate  tail.     The 
spinneret  is  sometimes  turned  nearly  at  right  angles  to        ^ 
the  axis  of  the  tail.     Flemming  solution  to  glycerine.  , 

Fig.  46. 

33-    M.  incurvus,  n.  sp.    Striae  resolvable  with  diffi-        «adsl 
culty  and  into  rows  of  dots.     Dorsal  onchus  opposed 
by  2  inconspic-    2.      7.4      28.       *63'2t      96.2  . 
uous,    ventrally    2.1    2.5        2.9       3.2         2.f^         "  msiln 

submedian    onchi    of    smaller    size   opposite   its   base. 
The  lining  of  the  oesophagus  is  a  prominent  feature,         strnurph 
occupying  about  two-thirds  of  the  apparent  width  of 
the  oesophagus.     Intestine  12  to  15  cells  in  girth,  not         "^ 
tessellated,   its  granules  numerous   and  fine.     Caudal         ^ 
glands    3,    broadly    saccate,    opposite   the    anus,    their 
ampullae  long  and  filling  the  posterior  part  of  the  tail.         XTSO 


SUBGENUS  MYLONCHULUS 


(S.  S.  469)]  57 


There  is  a  flattish  cardia.  Anus  raised.  Longitudinal  fields  two-fifths  to  one-third 
as  wide  as  the  body.  From  the  more  or  less  elevated  vulva  the  vagina  leads  inward 
at  right  angles  to  the  ventral  surface  one-third  the  distance  across  the  body.  The 
eggs  are  one  and  one-half  times  as  long  as  the  body  is  wide,  and  occur  one  at  a 
time  in  each  uterus.  The  ovaries  contain  about  a  dozen  developing  ova. 

Sandy  soil  in  a  cranberry  bog,  Arlington  Farm,  Virginia,  U.  S.  A.  Also  on  the 
margin  of  the  spring  that  gives  rise  to  Salt  River,  Jamaica.  Flemming  solution  to 
glycerine.  Fig.  47  (at  bottom  of  previous  page). 

34.  M.  sigmaturus,  n.  sp.  Two  very  inconspicuous  submedian  onchi  are  found 
opposite  the  base  of  the  dorsal  onchus,  just  at  the  base  of  the  rasps.  Intestine  10 
cells  in  girth,  comparatively  distinctly  tessellated.  The  rectum  is  about  as  long  as 
the  anal  body-diam-  2.3  12.  30.  >64'14  96.3 
eter,  and  is  some- 
what  sigmoid. 


ll2  """ 


2.4          2  3s       2.4 

The  anus  is  very  distinctly  visible  on 
account  of  its  contour,  and  on  account  of  the  refractive 
nature  of  the  lining  of  the  rectum.  What  appears  to  be 
a  renette  pore  exists  immediately  behind  the  nerve-ring. 
The  distinct  lateral  fields  are  about  one-fourth  as  wide 
as  the  body,  and  are  characterized  by  the  presence  in 
them  of  scattered  granules  much  smaller  in  size  than 
those  of  the  intestine.  The  posterior  part  of  the  tail  is 
somewhat  digitate,  and  the  whole  is  slightly  sigmoid.  From  the  anus  the  tail 
tapers  rapidly  to  near  the  middle,  so  that  if  the  posterior  half  were  lacking  the 
tail  would  be  rounded.  The  diameter  of  the  tail  at  the  middle  is  about  one-third 
as  great  as  at  the  base.  From  the  middle  onward  the  tail  for  a  short  distance  is 
of  uniform  diameter,  and  then  tapers  rather  rapidly  in  the  posterior  fourth  to  a 
rounded  or  subtruncated  spinneret.  Small,  somewhat  finger-shaped  setae  are  found 
on  the  tail  ;  one  dorsally  sublateral  pair,  a  trifle  in  front  of  the  anus  ;  another  dor- 
sally  sublateral  pair  near  the  middle  of  the  tail  but  located  on  the  more  bulky  part  ; 
finally,  a  third  ventrally  sublateral  pair  a  little  in  front  of  the  digitoid  part  of  the 
tail.  The  caudal  glands  are  opposite  the  rectum.  The  eggs  are  about  two  and  one- 
half  times  as  long  as  the  body  is  wide.  The  tapering  ovaries  contain  10  to  12 
developing  ova,  arranged  irregularly. 

Found  in  various  parts  of  the  United  States  and  Mexico.  Resembles  minor  and 
brachyuris,  from  which  it  may  be  distinguished  by  the  form  and  structure  of  the 
tail.  Flemming  solution  to  glycerine.  Fig.  48. 

35.  M.  subtenuis,  n.  sp.  Wall  and  dorsal  tooth  of  the  pharynx  rather  strongly 
developed.  When  the  lips  are  closed  the  pharynx  is  hardly  half  as  wide  as  long. 
Dorsal  tooth  slightly  arcuate,  its  point  located  close  to  the  base  of  the  lips.  The 
1.5  5.6  26.  ^72'22  97.  x  submedian  teeth 

—      -  £75         1>3;   l.»  »  are     easily    con- 

-Mi2       97.     .  fused      with      the 

He     TTa       TA    272       fTer  denticles.    Lining 

of  the  oesophagus  well  developed,  occupying  one-fourth 
of  the  longitudinal  optical  section.  There  is  a  small 
conoid  cardia.  Intestine  probably  about  6  cells  in  girth, 
not  definitely  tessellated.  Anus  raised  and  conspicuous, 
the  anterior  lip  somewhat  massive  and  overhanging. 
The  arcuate,  conoid  tail  ends  in  a  spinneret  one-fifth  to  one-sixth  as  wide  as  its 
base.  The  ovaries,  of  which  the  posterior  is  somewhat  the  smaller,  appear  to 
contain  about  a  dozen  ova.  Inconspicuous  papillae  appear  on  the  ventral  side  of 
the  female  near  the  vulva.  Two  were  noted  behind  the  vulva  and  one  or  more  in 


1.5 


6.2       25. 


*"r/* 


168  (S-S.470)  THE  MONONCHS 

front  of  it.  The  tail  of  the  male  is  somewhat  like  that  of  the  female  but  dimin 
ishes  very  suddenly  behind  the  anus.  Five  pairs  of  innervated  papillae  have  been 
seen  on  the  tail  of  the  male,  two  of  them,  however,  exceedingly  inconspicuous  and 
easily  overlooked :  Of  the  three  more  conspicuous,  one  ventrally  submedian  pair 
is  located  a  short  distance  behind  the  anus ;  a  second  dorsally  sublateral  pair  occurs 
a  little  behind  the  middle  of  the  tail,  and  a  third  subventral  pair  occurs  a  short 
distance  in  front  of  the  spinneret.  Of  the  two  more  inconspicuous  pairs,  one  is 
nearer  the  spinneret  than  that  just  mentioned,  and  the  other,  lateral,  and  slightly 
behind  the  middle  of  the  tail.  The  arcuate  spicula  are  about  one  and  one-fourth 
times  as  long  as  the  anal  body-diameter.  At  their  widest  part,  near  the  middle, 
they  are  about  one-fifth  to  one-sixth  as  wide  as  the  corresponding  part  of  the 
body  and  thence  taper  in  both  directions ;  they  are  not  cephalated.  The  distal  ends 
are  obscurely  two-pronged.  The  obscurely  bifurcated  accessory  pieces  are  of 
typical  form  and  size,  about  one-third  as  long  as  the  spicula  and  about  one-fourth 
as  wide  as  long.  Fourteen  rather  closely  approximated,  equidistant  supplementary 
organs  occur  in  front  of  the  anus,  occupying  a  distance  about  three  times  as  great 
as  the  length  of  the  tail.  Internally  the  organs  seem  to  be  short,  broad  tubes  of 
slightly  varying  diameter ;  these  are  probably  slightly  protrudable.  The  protrudable 
portion  is  not  hispid  as  is  the  case  in  M.  major; — on  the  contrary,  it  appears  to  be 
smooth.  The  anterior  one  and  the  posterior  three  of  these  organs  are  not  so  well 
developed  as  the  others,  that  near  the  anus  being  reduced  to  a  mere  innervation ; 
the  distance  between  this  latter  and  its  nearest  neighbor  is  about  twice  as  great  as 
between  any  other  adjacent  members  of  the  series.  These  organs  give  to  the  ven- 
tral contour  a  crenate  or  serrate  appearance.  The  anal  muscles  are  prominently 
developed.  The  ejaculatory  duct  is  often  filled  with  elongated  spermatozoa,  some- 
what resembling  those  of  Dorylaimus,  and  similar  in  form  to  those  figured  by 
Dr.  de  Man  for  M.  gerlachei.  Each  one  may  be  one-fourth  as  long  as  the  body  is 
wide,  or  thereabouts.  There  are  two  outstretched  testes.  The  blind  end  of  the 
anterior  is  about  as  far  behind  the  base  of  the  neck  as  the  latter  is  behind  the  anter- 
ior extremity.  The  blind  end  of  the  posterior  seems  to  lie  about  twice  as  far  in 
front  of  the  foremost  supplementary  organ  as  this  latter  is  in  front  of  the  anus. 
The  spicula  have  a  median  stiffening  piece,  and  their  proximal  ends  lie  toward  the 
dorsal  side  of  the  body. 

Found  about  the  roots  of  plants  on  the  Arlington  Farm,  Virginia,  U.  S.  A.  Re- 
sembles M.  minor,  but  in  the  proportions  of  the  pharynx  there  are  notable  differ- 
ences. The  walls  are  here  thicker;  the  amphids  are  larger  and  farther  back;  the 
lips  and  onchus  are  strongly  developed,  so  that  when  the  pharynx  is  closed  the 
cavity  appears  smaller  than  in  minor.  Opposite  the  anterior  supplementary  organ 
there  is  a  fibrous  ring,  probably  nervous.  A  similar  structure  has  been  noted  in 
other  species.  There  probably  exist  at  this  point  in  the  body  special  nerve  com- 
missures. Flemming  solution  to  glycerine.  Fig.  49  (near  bottom  of  previous  page). 
36.  M.  subsimilis,  n.  sp.  Striae  of  the  cuticle  more  or  less 
easy  of  resolution.  Lining  of  the  resophagus  strongly  developed, 
3.  10.  34.  Y  96.  occupying  three-fifths  of  the 

3.1  3.6  4.  3.8  2.6  '  m  longitudinal  optical  section. 
Anus  slightly  elevated,  especially  the  anterior  lip.  The  scat- 
tered granules  in  the  cells  of  the  intestine  are  small,  but  varia- 
ble in  size,  and  do  not  give  rise  to  tessellation.  The  more  or 
less  arcuate  tail  is  conoid  to  the  blunt  terminus,  which  is  about 
one-fourth  as  wide  as  the  base  of  the  tail.  A  ventrally  sublateral  innervated  papilla 
occurs  on  each  side  near  the  middle  of  the  tail.  There  are  no  caudal  glands.  De- 
scription derived  from  a  single  young  female. 


SUBGENUS  MYLONCHULUS 


(S.S.471)169 


About  the  roots  of  banana  plants  imported  from  Paris,  France.  Resembles 
brachyuris  and  minor,  but  differs  in  having  no  spinneret.  The  dorsal  onchus  is  set 
farther  back  in  the  pharynx  than  in  either  of  those  species,  and  there  are  no  traces 
of  submedian  teeth.  The  rasps  also  are  less  strongly  developed.  Flemming  solu- 
tion to  glycerine.  Fig.  50  (at  bottom  of  previous  page). 

37.  M.  obliquus,  n.  sp.    Two  small,  ventrally  submedian  onchi  present,  opposite 
the  base  of  the  dorsal  onchus.     (Esophagus  at  first  a  little  swollen;  its  lining  well 
developed,    and    occupy-  2.6      9.      31.      ^63'^      98. 

ing  one-fourth  of  the  27i  374 374  471  2.4  1>4  M 
optical  longitudinal  section.  Intestine  about  8  cells  in  girth, 
as  a  rule  not  distinctly  tessellated.  The  conoid  tail  is  slightly 
arcuate,  and  obliquely  truncate  at  the  spinneret,  which  is 
about  one-third  as  wide  as  the  base  of  the  tail.  The  three 
caudal  glands  are  located  opposite  the  rectum,  which  ends 
externally  in  a  slightly  elevated  anus.  The  ampullae  of  the 
caudal  glands  are  well  developed,  and  occupy  the  posterior 
two-thirds  of  the  tail.  Though  the  vuiva  is  more  or  less  con- 
tinuous with  the  ventral  surface,  it  is  conspicuous  on  account 
of  the  refractive  nature  of  the  walls  of  the  vagina.  The 
elongated  thick-shelled  eggs  are  two  and  one-half  times  as  long  as  the  body  is 
wide,  and  appear  to  be  deposited  before  segmentation  begins.  The  ovaries  contain 
about  a  dozen  developing  ova,  arranged  partly  single  file,  partly  irregularly.  A  pair 
of  ventrally  submedian  innervated  papillae  were  noted  near  the  middle  of  the  tail  of 
the  female. 

From  soil  from  Germany,  along  with  specimens  of  Heterodera  schachtii.  Re- 
sembles brachyuris,  from  which  it  seems  easily  distinguishable  by  the  large  thick- 
shelled  eggs.  Flemming  solution  to  glycerine.  The  habitat  led  to  the  suspicion  that 
it  was  feeding  on  H.  schachtii,  but  the  writer  was  unable  to  establish  the  fact  from 
the  few  specimens  available  for  examination.  Fig.  51. 

38.  M.  lacustris  Cobb.     The  amphids  have  the  form  of  "slits,"  3  to  4  times  as 
long  as  wide,  and  are  placed  at  the  base  of  the  lips  nearly  opposite  the  apex  of 

the  dorsal  onchus.  They     2.7      8.      28.      *63*      96.  /-^p^SscC H* 

are  about  one-sixth  as     275      372      379 472      2.3  ' 

wide  as  the  corresponding  portion  of  the  head.     Intestine 

from  15  to  20  cells  in  girth,  the  cells  closely  packed  with 

granules  of  variable  size  in  such  a  manner  as  to  give  rise 

to  a  close  and  obscure  tessellation.     The  well  developed 

lateral  fields  are  one-third  as  wide  as  the  body.    The  anus 

is 'slightly  raised.     The  lining  of  the  rectum  is  distinctly 

refractive.     The  tail  is  ventrally  arcuate,  and  ends   in  a 

blunt  spinneret  one-fourth  as  wide  as  its  base,  containing 

a   well    developed,    internally   ceratinized    spinneret.     The 

three  caudal  glands  are  arranged  tandem  in  the  anterior 

half  of  the  tail,  the  foremost  being  opposite  the  rectum.    The  spinneret  appears  to 

have  a  needle-shaped  valve.    A  pair  of  ventrally  submedian  innervated  papillae  has 

been  noted  a  little  in  front  of  the  spinneret  on  the  female.    The  eggs,  which  appear 

to  occur  one  at  a  time  in  the  uteri,  are  about  one  and  one-third  times  as  long  as  the 

body  is  wide  and  four-fifths  to  five-sixths  as  wide  as  the  body. 

Found  in  fresh  water  lakes,  Michigan,  U.  S.  A. ;  about  the  roots  of  ferns,  Panama 
Canal  Zone ;  and  in  the  Silver  Springs,  Florida.  Resembles  M.  brachyuris  Biitschli, 
from  which  it  differs  in  the  form  of  the  tail  and  spinneret.  M.  polonicus  Stefanski 
seems  to  closely  resemble  this  species.  Sublimate  to  balsam.  Fig.  52. 


17Q(S.S.472) 


THE  MONONCHS 


KM 


39.  M.  polonicus  Stefanski.     Two  minute  teeth  are  found  at  the  base  of  the 
buccal  cavity.    The  conoid  tail  is  somewhat  arcuate  from  the  raised  anus,  and  ends 
in  a  truncated  spinneret  one-fourth  as  wide  as  its  base.     The  three  caudal  glands 
are  located  in  a  tandem  series  in  the  anterior  third  of  the  tail. 

Description   derived   from  young  specimens   found   in  vegetable  detritus  in  the 
Czarna  River,  Poland.    Said  by  its  author  to  resemble  the  next  species,  No.  40. 

40.  M.  minor  Cobb.     There  are  2  minute,  submedian  onchi,  easily  overlooked. 
Amphids,  only  one-sixth  as  wide  as  the  corresponding  portion  of  the  head,  are 

2.3      7.5      26.      «eo*">     96.7  present  opposite  the 

274 275  27&  371  2~7T^  """  apex  of  the  dorsal 
tooth,  and  consist  of  arcuate,  refractive  markings  hav- 
ing their  convex  side  toward  the  lips.  They  appear  to 
be  about  one-fourth  as  wide  as  the  corresponding  por- 
tion of  the  head.  There  are  excessively  minute  striae  or 
dentations  of  the  inner  surface  of  the  margins  of  the 
lips;  these  structures  are  so  fine  that  they  might  easily 
escape  observation — much  finer  than  tne  rasp-like  teeth 
of  the  pharynx.  The  lining  of  the  oesophagus  occupies 
nearly  one-third  of  the  optical  longitudinal  section.  The 
cells  of  the  intestine  contain  small,  somewhat  uniform. 

rather  evenly  distributed  granules.  The  anus  is  slightly  raised,  the  anterior  lip 
being  a  little  more  pronounced  than  the  posterior.  The  conoid  tail  is  rather 
strongly  arcuate,  or  even  more  or  less  bent  near  the  middle.  The  comparatively 
well  developed  spinneret  is  one-third  as  wide  as  the  base  of  the  tail,  and  pos- 
sesses a  valve  similar  to  that  found  in  Mononchulus.  The  caudal  glands  are 
located  opposite  to,  or  a  little  behind  the  rectum.  The  lateral  fields  are  two- 
fifths  as  wide  as  the  body. 

This  is  a  cosmopolitan  species,  found  in  tropical  and  temperate  regions.    It  closely 
resembles  M.  brachyuris  of  Biitschli,  but  is  smaller  and  differs  somewhat  both  in 
the  structure  of  the  tail  and  in  that  of  the  pharynx.    Osmic  acid  to  water.    Fig.  53. 
41.    M.  brevicaudatus,  n.  sp.    Walls  of  the  pharynx  unusually  thick.    Two  ex- 
ceedingly small,  ventrally  submedian  onchi,  opposite  the  middle  of  the  dorsal  onchus. 
2.7      9.3      32.       >69'18      96.  Lining  of  the  cesoph- 

2.2  2.7  3.1  3.4  2.2  l'5  Bl11  agus  prominent,  oc- 
cupying one-third  of  the  optical  section.  Intestine  6  to  8 
cells  in  girth,  faintly  tessellated.  Contour  of  the  tail  like 
that  of  the  head  of  a  duck  whose  beak  is  very  short;  from 
the  anus  onward  having  roughly  an  equilateral  contour. 
Spinneret  more  elaborate  than  usual.  The  ceratinized 
walls  of  the  vagina  are  plainly  visible.  The  elongated 
eggs  are  two  to  two  and  one-half  times  as  long  as  the 
body  is  wide.  The  ovaries  taper  but  little.  About  a  dozen 
females  have  been  examined.  No  males  have  been  seen. 
Sperm  has  been  seen  at  the  flexure  in  the  ovaries.  The 
species  is  probably  syngonic. 

Found  about  the  roots  of  plants  in  a  cranberry  bog,  New 
Jersey,  U.  S.  A.  Resembles  micrurus  and  brachyuris  in  its  general  form,  but 
differs  in  the  details  of  the  pharynx  and  in  those  of  the  tail.  The  species  is  nema- 
tivorous,  and  also  feeds  upon  rotifers.  Sublimate  to  balsam.  Fig.  54,  in  which,  as 
m  many  of  the  original  illustrations  used  in  this  chapter,  what  at  first  sight  appear 
to  be  merely  lines  used  as  shading,  are  in  reality  carefully  charted  striae  or  lamina- 
tions of  the  wall  of  the  pharynx. 


SUB  GEN  US  ANATONCHUS 


(S.  s.473)  171 


42.  M.  japonicus,  n.  sp.     The  head  is  not  set  off  in  any  marked  fashion.    Am- 
phids  present  in  the  form  of  elliptical  markings  nearly  opposite  the  apex  of  the 
single  dorsal  tooth ;  the  length  of  their  long     2.1      e.9      30.      >67*      98. 

axes,  which  are  placed  transversely  on  the  274  271 279 27?  2~*  l'2  ma 
head,  is  probably  about  one-sixth  as  great  as  that  of  the  diameter  of  the  head.  The 
capacious  pharynx  is  somewhat  deeper  than  the  head  is  wide;  the  anterior  portion 
has  a  diameter  more  than  half  as  great  as  that  of  the  corresponding  portion  of  the 
head,  while  the  posterior  portion  has  a  diameter  about  two-fifths  as  great  as  that 
of  the  base  of  the  head.  The  single,  highly  refractive  dorsal  tooth  has  its  apex 
somewhat  in  front  of  the  middle  of  the  pharynx.  The  rasps  consist  of  5  to  6  rows 
of  teeth,  forming  a  group  whose  width  is  about  one-fifth  as  great  as  the  depth  of 
the  pharynx.  The  wall  of  the  pharynx  is  strongly  developed,  and  is  very  finely 
transversely  striated  in  the  posterior  part.  The  lining  of  the  oesophagus  is  an 
exceedingly  distinct  feature  throughout  its  length,  and  appears  to  occupy  about 
one-fourth  of  the  optical  longitudinal  section.  There  is  a  small  cardia.  Intestine, 
about  8  cells  in  girth,  very  obscurely  tessellated.  The  short,  blunt,  arcuate  conoid 
tail  is  truncated  at  the  terminus,  which  has  a  diameter  about  one-fourth  as  great  as 
that  of  the  base.  The  lateral  fields  are  about  one-third  as  wide  as  the  body,  and 
are  composed  of  2  rows  of  cells  containing  relatively  large  nuclei. 

This  species  rather  closely  resembles  a  number  of  others,  and  it  is  by  no  means 
certain  that  it  is  not  identical  with  some  one  of  them,  perhaps  consituting  a  variety. 
Curiously  enough,  it  was  found  in  Mississippi  Bay,  Yokohama,  Japan.  Sublimate 
to  balsam. 

43.  M.  tridentatus  de  Man.   At  the  base  of  the  pharynx  are  2  minute  denticles. 
Amphids  unknown.     Pharynx  more  or  less  triquetrous,  with  three  well  developed, 
2.          6.5       22.        '62'26 


2.1 
2. 


2.6 
6.5 


3. 

22. 


3.1 


3.2  mm 


2.7 


2.1  2.6  3.  3.1  2. 
double,  longitudinal  ribs  reaching  from 
end  to  end.  (Esophagus  at  first  slightly 
swollen.  Intestine  distinctly  tessellated. 
The  arcuate  tail  is  conoid  to  the  termi- 
nus, which  is  about  one-sixth  as  wide  as 
the  base  of  the  tail.  Each  of  the  slen- 
der, arcuate  spicula  is  cephalated  by 
contraction  and  is  supplied  throughout 
its  length  with  a  median  stiffening  piece, 
and  is  crossed  near  its  distal  extremity 
on  the  outside  by  one  of  the  rather 
broad,  two-pointed  accessory  pieces, 
which  are  one-half  as  long  as  the  spic- 
ula. Supplementary  organs  15  to  17, 
apparently  conical,  2  to  3  times  as  far 
apart  anteriorly  as  posteriorly,  where  they  are  nearly  contiguous.  The  posterior 
member  of  the  series,  the  whole  of  which  is  about  one  and  one-half  times  as  long 
as  the  tail,  is  somewhat  smaller  than  the  other  members,  and  is  located  a  short 
distance  in  front  of  the  anus.  On  the  tail  itself  are  a  number  of  papilhe,  dorsal  as 
well  as  ventral ;  2  pairs  on  the  anterior  half,  ventral,  and  2  pairs  on  the  posterior 
half,  dorsal.  It  remains  uncertain  whether  there  is  a  spinneret  and  caudal  glands. 
This  striking  species  seems  to  be  widespread  in  Europe  in  moist  soil,  and  i 
rath-er  common.  Fig.  55  (after  de  Man). 


j  72  <s- 


THE   MONONCHS 


44.  M.  gracilicaudatus  n.  sp.  Intestine  about  12  cells  in  girth.  The  anterior 
fifth  of  the  tail  is  arcuate  conoid  in  such  fashion  that  at  the  beginning  of  the  second 
fifth  the  diameter  is  about  one-third  to  one-  1.4  4.8  z\.  -M^8  65. 
fourth  as  great  as  at  the  anus.  Thence  on-  FTs  fTi  fTa  TTs  i.e'  D-l  B 
ward  the  tail  tapers  very  gradually  through  the  middle  third,  the  posterior  portion 
being  cylindroid  and  somewhat  narrower  than  the  spicula.  These  latter  are  uni- 
formly arcuate,  and  about  one  and  one-fourth  times  as  long  as  the  anal  body- 
diameter.  At  their  widest  part,  toward  the  proximal  end,  they  are  about  one- 
fifth  as  wide  as  the  corresponding  part  of  the  body.  They  taper  gently  in  each 
direction,  and  are  not  cephalated.  The  small  accessory  pieces  are  of  typical  form, 
only  about  one-fourth  as  long  as  the  spicula.  The  series  of  19  contiguous  supple- 
mentary organs  is  twice  as  long  as  the  spicula,  or  equals  3  body  diameters.  Anteri- 
orly the  organs  are  somewhat  larger  and  also  somewhat  farther  apart.  The  conical 
exterior  portion  of  each  organ  seems  to  be  more  or  less  protrudable.  These  organs 


X750 


inn 


are  similar  in  form  to  those  of  major,  though  they  are  not  echinulate.  The  anal 
and  post-anal  muscles  are  strongly  developed.  The  anal  muscles  are  found  through- 
out the  bulkier  portion  of  the  tail.  The  protruding  muscles  of  the  spicula  extend 
backward  in  the  tail  to  near  the  point  where  the  tail  diminishes  rapidly  in  diameter, 
and  there  join  the  ventral  part  of  the  caudal  wall.  The  post-anal  papillae  are  con- 
fined largely  to  the  more  massive  anterior  fifth  of  the  tail.  On  each  side  there  is 
a  ventrally  submedian  row  about  as  long  as  the  spicula,  consisting  of  4  to  5  mem- 
bers. Coextensive  with  them  is  a  ventral  row  of  3  to  4  papillae.  A  little  distance 
behind  these,  Avhere  the  tail  begins  to  be  smaller,  there  are  2  dorsally  submedian 


SUBGENUS  ANATONCHUS 


(S.s.475)  173 


innervated  papillae  of  smaller  size.  The  supplementary  organs  are  plainly  inner- 
vated and  the  nerves  can  be  traced  through  the  cuticle  and  through  the  body  mus- 
culature, and  seem  to  be  connected  with  internal  more  or  less  ellipsoidal  cells  whose 
nature  remains  unknown.  The  spinneret  is  very  inconspicuous.  The  nature  of  the 
caudal  glands  remains  uncertain. 

Found  in  marshy  ground,  Arlington  Farm,  Virginia,  U.  S.  A.,  about  the  roots  of 
fmpatiens,  in  black,  clayey  soil,  with  mud.  Resembles  M.  dolichurus  to  a  certain 
extent.  It  is  regrettable  that  only  a  few  specimens  have  been  available  for  exami- 
nation, as  it  is  a  species  well  adapted  to  throw  light  on  various  features  of  mon- 
onch  anatomy.  Fig.  56  (on  the  previous  page). 

Examination  of  the  pharyngeal  muscles  of  this  species  leads  to  a  partial  under- 
standing of  the  mechanics  of  the  lips.  The  muscles  which  move  the  lips  are  long 
and  slender,  and  pass  from  the  lips  backward  along  the  surface  of  the  pharyngeal 
capsule.  They  join  the  body  wall  some  distance  behind  the  pharynx.  There  are  2 
separate  groups  of  muscles,  extensors  and  flexors.  Of  the  6  extensors  2  are  shown 
in  the  illustration ;  these  are  furcated  opposite  the  middle  of  the  pharynx,  one  half 
of  each  going  to  the  lateral  lip;  the  other  half  to  a  submedian  lip.  The  joined 
fulcra  of  the  6  lips  form  a  framework  encircling  the  head.  The  extensors  pass 
outside  this  framework.  The  flexor  muscles  are  less  clearly  shown,  but  are  mani- 
festly better  developed.  A  group  of  3  is  shown  lying  between  the  2  extensors. 
They  appear  as  faint  bands  outside  the  pharynx  passing  forward,  and  beyond  doubt 
are  attached  to  the  lips  inside  the  ring  of  fulcra.  The  musculature  of  the  lips  is 
shown  in  the  illustration  and  is  further  explained  on  page  140  in  connection  with 
the  general  description  of  the  head. 

45.     M.   dolichurus   Ditlevsen.     Neck   tapering  but   little.     Pharynx   probably 
prismatic,  and  in  transverse  section  somewhat  triangular.    About  7  denticles  about 
the  base,  or  near  the  base,  of  the  pharynx.    The  arcuate  tail  tapers  to  the  terminus, 
which  is  about  one-eighth  as  wide 
as  the  base.     The  author  mentions 


*       '         ?    .         2.5       1.8 

the  presence  of  3  or  4  inconspicu- 
ously developed  lobes  at  the  base 
of  the  oesophagus,  and  it  would  « 
appear  from  his  figures  that  a  spin- 
neret and  caudal  glands  are  pres- 
ent, the  latter  forming  a  tandem 
series  near  the  anus.  Menzel  finds 
in  the  pharynx  of  Swiss  specimens  ^ 
of  this  species  3  teeth  of  equal  size ; 
that  is  to  say,  the  ventrally  sub- 
median  teeth  are  equal  in  size  to 
the  dorsal  tooth.  His  specimens 
are  ¥/2  to  5}/2  mm.  long,  and  this 
probably  represents  the  adult  size,  a 

Found  in  moist  soil  and  meadow 
land,  Jutland;  Switzerland.  Fig. 
57  (after  Ditlevsen).  Menzel  shows 
the  papillae  as  much  less  conspicu- 
ous, and  without  the  spherical  tips. 
The  original  material  consisted  of 
but  a  single  immature  female. 


174  (S' 


THE  MONONCHS 


46.  M.  digiturus  Cobb.  Amphids  occur  opposite  the  anterior  part  of  the 
pharynx.  What  appears  to  be  a  renette  pore  occurs  just  behind  the  nerve- ring. 
The  anal  region  3.3  8.  26.  »7012  92. 
is  somewhat 


1.4 


in.. 


3.          3.4          3.4          2.3 

raised.  Behind  the  anus  the  tail  diminishes  rapidly 
in  diameter,  so  that  at  the  end  of  the  anterior  fourth 
it  is  about  three-fifths  as  wide  as  at  the  anus. 
Thence,  for  some  distance  it  is  cylindrical,  but  be- 
comes somewhat  abruptly  convex-conoid  in  the  pos- 
terior fifth  and  ends  in  a  rather  narrow,  inconspicu- 
ous .spinneret.  The  lining  of  the  oesophagus  is  a  con- 
spicuous feature.  Intestine  not  tessellated.  The 
longitudinal  ribs  of  the  inner  wall  of  the  pharynx 
are  rather  conspicuous  features,  and  extend  from 
end  to  end  of  the  pharynx. 

Found    about    the    roots    of    banana    plants,    Fiji. 
Fig.  58.       . 

47.  M.   trichurus,   n.   sp.     This  outstanding   form   has  an   oesophagus  that  is 
slightly  swollen  where  it  receives  the  pharynx.     The  lining  of  the  oesophagus  is 

2.6      7.        21.       '5211      67.  prominent,  occupying 

2.3  .  2.4  278  279 1.8  l"  ™*  three-fifths  of  the  op- 
tical section.  Longitudinal  fields  one-fourth  as  wide  as  the 
body.  Characters  well  set  forth  in  fig.  14,  p.  146. 

Found  about  the  roots  of  orange  trees,  Bahia,  Brazil. 
Bears  considerable  resemblance  to  M.  gymnolaimus.  It  ap- 
pears possible  from  these  investigations  that  the  tropical 
mononchs,  when  more  fully  known,  will  prove  especially 
interesting.  Nearly  all  the  more  striking  species  here  re- 
corded are  from  the  tropics.  The  warm  soils  of  the  tropical 

regions  teem  with  nematodes,  many  of 

them  no  doubt,  especialy  adapted  to  the 

peculiar  conditions  found  there.     The 

predatory  mononchs  in  such  soils  will 

naturally    enough    have    responded    in 

structure  not  only  to  the  climatic  con- 
ditions, but  also  to  the  form  and  habits 

of  their  quarry.    Fig.  59  (just  above).  /  i'::$Viar "" 

48.  M.  gymnolaimus  Cobb.     The 
more   or   less   triquetrous   pharynx    is 
strongly  three-ribbed.     Cardia  of  such 

2.6       6.8       24.        '6716       86. 


2.S  mm 


2.2  2.3  2.7  2.5  1.6 
a  nature  as  to  give  rise  to  a  double 
constriction  in  the  cardiac  region.  In- 
testine about  12  cells  in  girth.  What 
appears  to  be  a  renette  pore  occurs 
immediately  behind  the  nerve-ring. 
The  lateral  fields  are  about  one-fifth 
as  wide  as  the  bodv.  The  tail  tapers 
regularly  to  near  the  terminus ;  it  is, 

however,   cylindroid  for  a   short  distance  in   front  of  the  spinneret.     Vulva  not 
prominent.     The  uterus  is  as  long  as  the  reflexed  portion  of  the  ovary,   which 


SUB  GENUS  IOTONCHUS 


(S.  S.  477)  175 


reaches  two-fifths  the  way.  back  to  the  vulva.     The  ova  are   for  the  most  part 
arranged  single  file. 

This  nemativorous  species  will  probably  prove  cosmopolitan.  About  roots  of 
banana,  Fiji;  of  Platonia  insignis,  Rio  Janeiro,  Brazil;  roots  of  various  plants, 
Arlington  Farm,  Virginia,  U.  S.  A.  Fig.  60  (on  the  previous  page). 

49.  M.  consimilis,  n.  sp.     Amphids,  unlike  those  of  gymnolaimus,  apparently 
duplex,  located  a  little  behind  the  base  of  the  lips ;  one-fourth  as  wide  as  the  cor- 
responding portion  of  the  head.     Wall  of  the  pharynx  strongly  developed. 

Rather  closely  resem-  3.2  9.1  26.  68'  86. 
bles  M.  gymnolaimus,  2.4  2.7  2.7  2.4  2.1  1-1  M 
but  has  the  walls  of  the  pharynx  much  more  strongly  cer- 
atinized,  and  is  of  much  smaller  size.  The  pharynx  is  j~ela- 
tively  SO  per  cent  longer.  The  spinneret  is  not  swollen  as 
in  gymnolaimus.  Description  and  figures  derived  from  a 
single,  immature  female  specimen  from  about  the  roots  of 
Platonia  insignis  Mart.,  Brazil.  The  figure  of  gymnolaimus 
shows,  on  the  ventral  side,  near  the  front  of  the  pharynx,  an 
inward  projection,  probably  representing  the  optical  section 
of  the  junction  of  elements  in  the  pharyngeal  wall.  No 
such  appearance  was  observed  in  consimilis.  Fig.  61. 

50.  M.  rapax,  n.  sp.     Intestine  about  12  to  20  cells  in  girth,  faintly  tessellated. 
The  female  organs 'are  probably  double  and  symmetrical.     The  conoid  tail  tapers 

somewhat  in  front  of  the  anus  to  a 
plain,  symmetrical,  unarmed  spin- 

2.5     6.5     21.        61.       90.      , 
27 272       276       271 fTT^*  dl 

neret  about  one-sixth  as  wide  as  its 
base.  One  and  one-half  tail-lengths 
in  front  of  the  anus  there  is  a  con- 
striction in  the  intestine,  which  ap- 
pears to  be  due  to  the  presence  in 
that  region  of  '  commissures,  as  if, 
possibly,  nerves  encircled  the  intes- 
tine at  that  part. 

Found  about  the  roots  of  plants, 
Arlington  Farm,  Virginia,  U.  S.  A. 
Nemativorous.  Only  young  females 
have  been  seen.  As  its  name,  rapax, 
indicates,  this  species  is  a  rapacious 
one,  swallowing  other  nemas  whole, 
even  when  half  as  long  as  itself. 
Fig.  62. 

51.  M.  rex  Cobb.     This  "king"  of  the  mononchs  has  low,  broad,  inconspicuous 
labial  papillae  that  do  not  interfere  materially  with  the  rounded  contour  of  the 
front  of  the  head.    The  lips  are  bulky  and  powerful.    No  amphids  have  been  seen. 
The  pharynx  is  armed  with  very  powerful      2.      6.      20.      'se*37      ei. 
muscles.     The  intestine  is  tessellated.     The      fTe UT      2~.         ?72 

lateral  fields  are  one-fifth  as  wide  as  the      2       5>5      20>      M50 
body.     The  conoid  tail  tapers  more  rapidly      us    F79 271    iTa         t.5  '  0-a-y-mB 
at  first,  being  nearly  cylindroid  in  the  posterior  two-thirds,  where  it  is  about  one- 
eighth  as  wide  as  at  the  anus.    The  spinneret,  which  is  slightly  expanded,  bears  two 
ventrally  submedian  papillae,  after  the  manner  of  longicaudatus ,  but  slightly  larger 


1.4 

86. 


THE  MONONCHS 


in  proportion.  Three  caudal  glands  are  present.  Each  uterus  is  capable  of  carrying 
one  and  possibly  two  eggs  at  a  time.  These  are  about  one  and  one-fourth  times  as 
long  as  the  body  is  wide,  and  half  as  wide  as  long.  The  tail  of  the  male  tapers 
more  rapidly  at  first  than  that  of  his  mate.  Supplementary  organs  17,  prominent, 
closely  approximated,  equidistant,  occupying  a  space  equal  to  one  and  one-half 
times  the  length  of  the  tail.  The  spicula  are  about  twice  as  long  as  the  anal  body- 
diameter. 

Found  at  depths  of  from  about  200  to  1200  feet  in  Lakes  Manapouri  and  Wak- 
atipu,  New  Zealand. 

1.6       8.        17.       <63'26       9<V 


1.4 


5.2 


52.    M.  regius,  n. 

sp.  Amphids  rela- 
tively small,  con- 
nected with  a  nar- 
row, internal,  appar- 
ently tubular  ele- 
ment passing  back- 
ward past  the  base 
of  the  pharynx. 
Pharyngeal  muscles 
strongly  developed, 
extending  backward 
from  the  base  of 
the  lips  to  the  body 
wall  behind  the 
pharynx.  Each  of 
the  six  lips  with  a 
flat,  flap-like  outer 
accessory  part, 
which  is  longitudi- 
nally striated  at  the 
base.  Onchi  sub- 
equal,  the  dorsal 
Found  about  the  roots  of  plants,  Arlington  Farm,  Virginia, 


X750 


slightly  the  stronger. 
U.  S.  A.    Fig.  63. 

53.  M.  bathybius  Micoletzky.  In  the  figure  the  onchus  labeled  "submedian"  is 
really  a  subdorsal  onchus.  In  addition  to  this  subdorsal  onchus  there  are  still 
others,  probably  4.9  to.  30.  63Y  87. 
2  to  3  pairs,  which  3.3  3.6  3.9  3.4  2.5  '6  mn 
in  profile  view  have  a  double  contour.  It  remains 
uncertain  whether  the  other  markings  seen  on  the 
wall  of  the  pharynx  are  projections  or  pores. 

The  author  considers  this  species  to  be  related  to 
M.  gerlachei  de  Man,  the  lip  region  and  vestibule  of 
the  two  species  being  similar.  However,  the  armature 
of  the  pharynx  in  the  two  species  is  quite  different. 

Found  in  mud  at  a  depth  of  about  300  feet  in  the 
Atter  Lake,  Austria.  The  description  and  figures  rest 
upon  the  examination  of  a  single  immature  specimen,  and  it  is  probable  that  the 
examination  of  further  specimens  will  improve  our  knowledge  of  this  interesting 
form.  Fig.  64  (after  Micoletzky).  For  53b,  M.  fasciatus,  n.  sp.,  and  53c,  M. 
similis  Cobb,  see  Appendix,  p.  184. 


SUBGENUS  IOTONCHUS 


(S.  S.479)  177 


.._  on? 


54.  M-  studeri  Steiner.     Wall  of  the  pharynx  presenting  5  longitudinal  ribs, 
four  of  them  in  2  pairs,  the  fifth  single.     At  the  base  of  the  pharynx  numerous 
small  denticles,  arranged  in  rows  of  from  three  to  four.     (Esophagus  powerful. 

2.8?  •  ?     26.      67.       94. .  A    little   in    front 

?          ?       ?         3.4       ?  Of     the     posterior 

2.8?      ?     27.      H       95.4.  end  of  the  cesoph- 

?  ~  ?  3TI Te^  '  agus  there  are  3 
powerful  teeth  which,  according  to  Steiner,  "are 
similar  to  those  seen  in  Mononchus  dolichurus." 
Tail  of  the  male  arcuate,  conoid  to  the  spinneret, 
which  is  about  one-fourth  as  wide  as  the  base.  The 
three  caudal  glands  form  a  tandem  series  in  the  an- 
terior half  of  the  tail.  The  slightly  arcuate  spicula 
in  their  widest  part  are  about  one-sixth  as  wide  as 
the  corresponding  portion  of  the  body.  They  taper 
slightly  at  either  end,  and  are  about  one  and  one- 
third  times  as  long  as  the  anal  body-diameter.  They 
are  not  cephalated.  The  accessory  pieces  appear  to 
be  of  the  usual  character.  The  twelve  short,  tubular, 
equidistant  supplementary  organs,  occupying  a  space  equal  to  twice  the  length  of 
the  tail,  do  not  interfere  materially  with  the  ventral  contour.  The  internal  tubular 
parts  are  about  as  long  as  the  spicula  are  wide.  Distance  from  the  anus  to  the 
posterior  supplementary  organ  is  nearly  twice  as  great  as  the  distance  between  the 
adjacent  organs.  Two  pairs  of  post-anal  papillae  were  noted. 

Found  on  the  island  of  Ufenau  in  the  Zurich  Lake,  under  moss.     Fig.  65  (after 
Steiner). 

55.  M.  zschokkei  Menzel.    This  species,  one  male  to  each  three  to  four  females, 
is  found  in  various  parts  of  the  Austrian  and  Swiss  Alps.     Neck  and  oesophagus 
3.?       ?       25.        '66'         95. 


25. 


3.4 
96. 


2.4-3.5  mm 

denticles 


?       '         ?  3.6       2.4 

tapering  but  little.  Small 
often  occur  at  the  base  of  the  pharyn- 
geal  cavity.  Uterus  capable  of  con- 
taining one  or  two  eggs.  The  blunted 
terminus  of  the  conoid  arcuate  tail  is 
about  one-eighth  as  wide  as  the  base. 
The  slightly  arcuate  spicula  are  rather 
slender,  each,  however,  having  a  stif- 
fening piece  in  its  distal  half.  Acces- 
sory pieces  as  figured  by  de  Man  for 
his  M.  brachyuris  Butschli.  Beginning 
near  the  anus  the  21  projecting,  ob- 
liquely conical,  equidistant,  contiguous 
supplementary  organs,  each  as  high  as 
wide,  occupy  a  space  3  times  as  long 
as  the  tail. 

Found  in  the  high  Swiss  Alps.   Fig. 
67,  after  Menzel,  who  considers  that 


of'all  the  European  mononchs  at  present  known,  zschokkei  has  close  affinity  only 
with  M.  parvus  de  Man,  from  which  it  differs  in  the  position  of  the  onchus  and 
the  relative  abundance  of  males. 


THE  MONONCHS 


56.  M.  brachylaimus,  n.  sp.  There  are  two  exceedingly  minute,  almost  invisible, 
apparently  rudimentary,  ventrally  submedian,  conical,  forward-pointing  toothlets  at 
the  base  of  the  pharynx.  These  are  not  shown  in  the  illustration.  Three  slightly 

2.4       7.        21.        6514 


10  it 


(fee 


2.4 

2.3 


2.4 

7.4 


2,8 

19. 


94. 
1.9 

94, 


2.5       2.5 


>  3.5  m 


arcuate,  duplex,  longitudinal  ribs 
strengthen  the  walls  of  the  phar- 
ynx and  reach  from  end  to  end, 
one  being  dorsal,  the  other  two 
ventrally  submedian.  Amphids 
difficult  to  see.  (Esophagus  at 
first  slightly  expanded.  The  ces- 
ophageal  lining  is  not  so  promi- 
nent as  in  many  other  species;  its 
optical  section  finds  expression  in 
3  or  4  parallel  lines,  occupying 
about  one-fourth  of  the  longitu- 
dinal optical  section.  There  is  an 
inconspicuous,  flattish  cardia.  In- 
testine about  8  to  12  cells  in  girth, 
faintly  tessellated.  The  tail  is 
conoid  to  the  plain,  unarmed  con- 
oid terminus.  The  base  of  the  spinneret  is  about  one-fifth  as  wide  as  the  base  of 
the  tail.  The  clavate  caudal  glands  form  a  close  tandem  in  the  anterior  third  of 
the  tail.  The  anus  has  rather  conspicuous,  with  well  developed,  though  not  protrud- 
ing lips.  There  is  a  pair  of  innervated  lateral  papillae  near  the  middle  of  the  tail  of 
the  female.  Both  in  front  of  and  behind  the  vulva,  especially  behind,  there  are 
inconspicuous  papillae,  occupying  a  distance  equal  to  twice  to  thrice  the  length  of 
the  body-diameter.  The  two  equal,  arcuate,  rather  slender  spicula  are  one  and 
one-half  times  as  long  as  the  anal  body-diameter,  and  are  of  nearly  uniform  size 
throughout  the  greater  part  of  their  length.  However,  beginning  near  the  slightly 
truncated  tips  they  taper  slightly  in  the  distal  sixth.  The  proximal  ends  are  also 
narrowed  slightly  and  lie  well  toward  the  dorsal  side  of  the  body,  at  any  rate  when 
the  body  is  incurved.  The  two  accessory  pieces,  each  about  two-thirds  as  wide  as 
the  spicula,  are  located  opposite  the  distal  portions  of  these  latter.  When  seen  in 
profile  they  appear  to  lie  nearly  at  right  angles  to  the  body  axis,  and  seem  to  cross 
the  distal  parts  of  the  spicula.  They  are  about  two  to  three  times  as  long  as  wide, 
and  their  distal  extremities  are  diminished  and  bifurcated,  the  two  prongs  of  the 
fork  forming  a  U-shaped  figure.  When  at  rest  these  accessory  pieces,  as  usual, 
are  well  inside  the  anus,  in  fact  appear  as  if  lying  immediately  under  the  lateral 
fields.  In  front  of  the  anus  there  is  a  uniform  series  of  about  16  equidistant, 
closely  approximated,  innervated  supplementary  organs,  occupying  a  distance  about 
equal  to  the  length  of  the  tail.  When  the  tail  end  of  the  body  is  incurved,  each 
organ  appears  on  the  ventral  contour  as  a  flattish  cone,  at  the  apex  of  which  is  a 
nerve  ending,  which  from  this  point  extends  inward  and  forward. 

Brown,  sandy  soil,  Arlington  Farm,  Virginia,  U.  S.  A.  This  nemativorous 'mon- 
onch  is  distinguished  from  all  others  by  the  relative  broadness  of  the  pharynx, 
and  by  the  position  and  size  of  the  basal  onchi.  Especially  well  adapted  to  show  the 
structure  of  the  lip  muscles  and  other  organs  of  the  head.  Fig.  67. 


SOIL  FERTILITY 


(s.  s.  481)  170 


57-    M.  acutus,  n.  sp.     CEsophagus  bulbous  at  first,  the  swelling  being  prolate. 
Intestine  about  10  cells  in  girth.    The  arcuate  conoid  tail  is  practically  acute.    There 


is  a  pair  of     2.6 
sublateral,     2.7 


7.5       23. 


94. 


8.1 


Hi. 


3.2         3.3         3.4 

innervated  papillae  near  the  beginning  of  the  pos- 
terior third  of  the  tail.  Anus  not  raised.  Fig.  68. 
Found  about  the  roots  of  rhubarb  in  loose, 
brown,  sandy  soil,  Arlington  Farm,  Virginia, 
U.  S.  A.  Nemativorous.  One  specimen  was  ob- 
served which  had  swallowed  another  mononch. 
This  is  one  of  the  most  instructive  forms.  It  is 
desirable  that  the  more  minute  structural  details 
of  nemas  be  very  carefully  investigated  with  a  view 
to  increasing  our  knowledge  of  their  comparative 
anatomy.  The  different  parts  of  the  digestive  or- 
gans of  nemas,  small  as  they  are,  are  as  pro- 
foundly modified  in  harmony  with  the  nature  of  the 
food  as  those  of  higher  animals.  The  digestion  of  starch  requires  a  different 
organic  mechanism  from  that  for  digesting  meat.  The  nemas  have  specialized  to 
a  high  degree  in  the  matter  of  food,  and  their  digestive  organs  are  correspondingly 
diversified. 

NEMAS  AND  SOIL  FERTILITY 

No  one  with  a  grain  of  imagination  can  engage  in  such  studies  as  the 
foregoing  without  sooner  or  later  asking  himself  questions  of  a  general 
nature  concerning  the  biology  of  the  soil,  for  he  gradually  comes  to  sec 
how  almost  infinitely  numerous  and  varied  are  the  organisms  inhabiting 
it;  a  population  in  which  the  nemas  are  but  an  element.  The  answers  to 
these  questions  will  lead  to  a  new  view  of  soil  fertility. 

The  revolution  wrought  by  Liebig's  ideas  concerning  the  chemistry  of 
the  soil  spent  itself  only  to  show  us  that,  grand  as  it  was,  it  was  little 
more  than  an  overture.  Subtler  forces  and  more  intricate  relationships 
than  any  indicated  in  these  earlier  conceptions  must  be  considered.  We 
now  see,  or  are  beginning  to  see,  that  the  value  of  manure  and  of  the  ro- 
tation of  crops  is  to  be  explained  not  simply  on  the  basis  of  the  exhaus- 
tion of  certain  elements  in  the  soil,  but  also,  and  probably  in  some  in- 
stances mainly,  on  the  basis  of  an  opposite  process,  an  accumulation  of 
certain  organisms  and  substances  in  the  soil.  Who  knows  but  that  the 
existence  of  annuals  may  be  due  in  some  measure  to  this  latter  fact?  May 
not  these  elaborate  provisions  for  the  distribution  of  the  seeds  of  annuals 
be  in  some  measure  a  means  of  escaping  these  accumulated  hostile  forces 
in  the  soil  ? 

After  all  the  word  Agriculture  is  more  or  less  of  a  misnomer.  We 
cultivate,  not  so  much  the  field,  as  plants.  What  we  are  really  after  is 
sunshine,  for  we  are  lost  unless  we  can  convert  our  infinitesimal  part  of 
the  energy  of  this  nearest  star  into  food,  clothing  and  shelter.  This  we 
do  by  utilizing  the  life  forces  of  certain  plants  and  animals,  and  these  are 
not  so  few  as  we  dreamed  in  our  older  philosophy,  for  none  of  our 
"domesticated  organisms"  can  any  longer  be  considered  by  itself.  Every 


lgQ(S.S.482)  THE  MONONCHS 

such  organism  is  reared  in  the  midst  of  a  host  of  other  organisms,  visible 
and  invisible,  and  often  it  is  these  others  that  determine  agricultural  suc- 
cess or  failure. 

The  soil  is  the  habitation  of  a  vast  community  of  beings  with  all  the 
attributes  of  other  huge  agglomerations  of  living  things  having  varying 
needs,  instincts  and  aspirations;  and  it  is  just  as  inappropriate  to  look 
upon  it  as  inorganic  as  it  would  be  to  look  upon  a  great  city  as  merely  an 
agglomeration  of  hills,  streets  and  houses.  Here  in  the  soil  are  beings  in 
enormous  variety;  multiplying,  growing,  dying;  competing,  fighting,  co- 
operating one  with  another,  with  an  activity  almost  if  not  quite  defying 
the  imagination,  and  we  need  what  may  be  called  soil  biologists  or  geo- 
biologists,  who  shall  understand,  as  far  as  possible,  this  interplay  of  life 
forces  that  gives  us  food,  fiber  and  fuel.  To  a  considerable  degree  our 
progress  in  agricultural  knowledge  in  the  not  distant  future  will  be  in  pro- 
portion to  the  firmness  with  which  we  lay  hold  of  and  act  on  this  idea. 

SUMMARY 

1.  The  genus  Mononchus  is  composed  of  scores,  possibly  hundreds, 
of  species,  divisible  into  distinct  subgenera.     The  number  of  known 
species  is  hereby  more  than  doubled. 

2.  The  genus  is  of  world-wide  distribution,  and  many  of  the  species 
are  cosmopolitan.    Mononchs  occur  in  all  kinds  of  arable  soil,  sometimes 
in  hundreds  of  millions  per  acre. 

3.  Most  mononchs,  probably  all,  are  strictly  carnivorous.    They  feed 
on  a  variety  of  living  microzoa,  prominent  among  which  are  other  nemas. 

4.  Injurious  nemas  are  devoured  by  mononchs,  and  it  is  desirable  that 
this  trait  of  mononchs  be  carefully  investigated  with  a  view  to  utilizing  it, 
if  possible,  in  diminishing  the  enormous  crop  losses  due  to  plant  infesting 
nemas — losses  amounting  to  many  millions  of  dollars  annually. 

5.  The  lips  are  moved  by  long  muscles,  connecting  proximally  with 
the  body  wall  behind  the  pharynx.     These  muscles  lie  along  the  outer 
surface  of  the  pharyngeal  capsule  and  act  in  such  a  way  as  to  pull  the 
lips  inward  and  outward  radially  about  a  series  of  fulcra  existing  in  a 
framework  encircling  the  head  along  the  margin  of  the  pharynx.     The 
lips  are  the  mechanical  complements  of  the  dorsal  tooth  and  denticles. 
While  most  mononchs  bolt  their  food,  some  give  it  a  certain  degree  of 
mastication.    The  appetite  is  sometimes  voracious. 

6.  Many  mononchs,  probably  most,  are  hermaphroditic,  even  to  the 
degree  of  syngonism.    In  the  typical  case  investigated  the  minute  sperm 
cells  of  female  origin  are  functional. 

7.  Well  developed  glands,  salivary  in  character,  occur  in  the  mon- 
onch  oesophagus,  and  empty  duectly  into  its  lumen,  and  both  indirectly 
and  directly  into  the  mouth  cavity. 


BIBLIOGRAPHY  (S.  s.  483)  jgl 

8.  What  appears  to  be  an  excretory  pore  of  the  usual  type  seems 
universal  near  the  nerve  ring. 

9.  The  outer  labial  papillae  are  the  homologues  of  the  ordinary  cepha- 
lic setae  of  other  nemas,  and  are  therefore  most  probably  tactile  in  func- 
tion.    This  leaves  it  probable  that  the  inner  papillae  are  devoted  to  the 
senses  of  taste  and  smell. 

10.  Amphids  are  always  present  in  the  form  of  small  lateral  more  or 
less  elliptical  structures  near  the  lips,  and  are  connected  with  internal 
elements  extending  inward  and  backward. 

11.  A  functional  spinneret  is  present  in  a  majority  of  the  species. 

12.  The  cuticle  is  always  finely  transversely  striated. 

13.  Mononchs  probably  moult  four  times. 

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(S.  S.  486) 

THE   MONONCHS 
APPENDIX 

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8        p"^--  ^^-v-f'M                    $$ 

.!        !            j" 

#?  >5!r/?er  oe  lit    w         tic        OP         im         an      spn 

The  above  diagram  illustrates  the  decimal  formula  used  herein.  6,  7,  8,  10,  6  are 
the  transverse  measurements,  while  7,  14,  28,  50,  88  are  the  corresponding  longitudi- 
nal measurements.  The  formula  in  this  case  is :  - — 14-  28' — 50-  88-.  The  unit  of 

6.      7.      8.    10.      6. 

measurement  is  the  hundredth  part  of  the  length  of  the  body,  whatever  that  may  be. 
The  measurements  become,  therefore,  percentages  of  the  length.  The  absolute  length 
is  given  in  millimeters  as  a  final  non-paired  term.  The  measurements  are  taken 
with  the  nema  viewed  in  profile ;  the  first  are  taken  at  the  base  of  the  pharynx,  the 
second  at  the  nerve-ring,  the  third  at  the  cardiac  collum  or  end  of  the  neck,  the 
fourth  at  the  vulva  in  females  and  at  the  middle  (M)  in  males,  the  fifth  at  the  anus. 
Fig.  68.  M.  recessus,  n.  sp.  No.  21-b.  Striae  excessively 
fine.  Lips  with  14  papillae.  Intestine  about  5  cells  in  girth, 
2.8  6.9  30.  '6312  91.5  faintly  tessellated.  Cau- 

2^ 27i 27? 274 TF^  dal    glands    small    and 

inconspicuous.  Tail  tapering  rapidly  on  the  ventral  side 
behind  the  anus ;  thence  onward  arcuate  and  conoid,  with 
spinneret.  Habitat:  soil  of  a  tomato  field,  Naranjo,  Fla. 
This  species,  together  with  decurrens  and  dentatus,  constitute 
the  new  sub-genus  Sporonchulus;  it  is  interesting  to  note 
that  so  far  as  known  all  of  them  are  tropical  and  below  the 
x  750  ^  m  ^—  i"  average  size. 

Fig.  69.    M.  decurrens,  n.  sp.    No.  21-c.     Striae  excessively 
fine.     Intestine   7  to  8  cells  in  girth,  the  cells  packed  with 
granules,    which,   however      2.9     9.      24.         Y       95.9 
do  not  give  rise  to  a  tessel-      2-9      4.       4.2       4.6     2. 
lated  appearance.    Tail  arcuate  conoid,  tapering  from  in  front 
of  the  anus.    No  spinneret,  or  doubtful ;  no  caudal  glands.   Ex- 
cretory pore  (?)  just  behind  the  nerve  ring.     Anus  more  or 
less  elevated.   Habitat :  Plant  Introduction  Gardens,  Miami,  Fla. 

53-b.    M.  fasciatus,  n.  sp.    Like  M.  bathybius,  No.  53.     Characterized  by  large, 
powerful  lips,  set  off  by  a  deep  constriction,  in   2.4    5.6    16.      '64'="    90.      ^  ^  ^ 
the  depths  of  which  is  a  double  refractive  line.    2.3    2.3     2.4      2.4      1.8 
Teeth  3,   small,  equal,  sub-basal ;  tail  conoid,  no  spinneret.   Papillae  14.     Habitat : 
About  roots  of  camphor,  Florida.     Nemativorous. 

Erratum. 

After  Soil  Science  went  to  press  it  was  found  that  similis  and  tenuis  are  invalid 
as  designations  of  new  mononchs,  owing  to  Mononchus  similis  Cobb  1893,  and 
Mononchus  tenuis  Daday  1908,  the  latter  not  a  mononch.  The  present  M.  similis  is 
therefore  hereby  changed  to  M.  subsimilis,  and  M.  tenuis  to  M.  sub  tenuis.  The  ref- 
erence to  M.  megalaimus  in  "Nematodes  mostly  Australian  and  Fijian,"  Cobb,  is  a 
misprint  for  M.  gymnolaimus.  The  overlooked  M.  similis  is  as  follows : 

53C.     M.   similis   Cobb.  3.3    8.      24.      u'58'u    86.  Pharynx  three-fifths   as 

wide   as    the    head,     two-  3.      sTs 471 4~5        2A  1-8  mni    thirds  as  wide  as  long ; 
tessellated  intestine  fifteen  cells  in  girth ;   anus  conspicuous,  depressed ;   spinneret 


one-eighth  as  wide  as  the  base  of  the  tail. 
Clarence  River,  Australia. 


Habitat :  About  roots  of  cane,  Harwood, 


MONONCHUS 


SUBGENERA 

MYLONCHULUS 


PRIONCHULUS 

longicollis 


GENUS 

MONONCHUS 


IOTONCHUS 

consunilis  bathybius 

fff  flrf 


SUBGENERA 

SPORONCHULUS  ANATONCHUS 


acutus 


FILTER-BED  NEMAS: 

NEMATODES  OF  THE  SLOW  SAND  FILTER-BEDS 
OF  AMERICAN  CITIES 

(Including  new  genera  and  species) 

WITH   NOTES   ON  HERMAPHRODITISM  AND 
PARTHENOGENESIS* 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY,  VII 
BY  N.  A.  COBB 

United  States  Department  of  Agriculture 

The  nemas  here  described  were  collected  from  the  filter-beds  of 
several  American  cities,  incident  to  a  rather  extensive  investigation 
of  nemas  of  economic  interest.  A  study  of  them  has  afforded  me  such 
an  interesting  and  suggestive  glimpse  of  the  biological  conditions  in 
slow  sand  filter-beds  that  I  venture  to  think  an  account  of  it  may  be 
of  some  slight  use  to  sanitarians,  and  to  engineers  connected  with  city 
and  town  water  works.  The  biological  observations,  more  particu- 
larly those  on  the  vanishing  series  of  spermatozoa  in  syngones,  may 
prove  of  interest  to  zoologists  and  geneticists. 

NATURE  AND  NUMBER  OF  THE  ORGANISMS  FOUND 

Few  Green  Organisms.  Comparatively  few  green  organisms  occur 
in  covered  slow  sand  filter-beds,  especially  if  the  water  passes  through 
a  subsidence  reservoir  before  entering  the  beds.  Practically  all  the 
living  forms  found  are  colorless  or  nearly  so,  and  most  of  the  larger  ones 
are  animal.  To  me  the  most  striking  organisms  in  every  sample  of 
sand  examined  were  the  nemas. 

Period  of  Use.  Renewal.  From  time  to  time  a  few  inches  of  the 
topmost  sand  of  slow  filter-beds  is  renewed;  the  old  sand  is  removed  and 
fresh  sand  spread  in  its  place.  The  period  of  use,  the  time  between 
any  two  successive  renewals,  varies  from  a  few  weeks  to  a  few  months, 
according  to  the  practice  of  the  engineer  in  charge.  Toward  the  end 
of  a  period  of  use  the  number  of  nemas  in  the  topmost  three  inches  of  a 
bed  often  mounts  to  hundreds  of  millions  per  acre,  and  sometimes 
exceeds  a  thousand  millions  per  acre.  At  this  latter  figure  each  glass 
of  drinking  water  must  percolate  through  sand  containing  at  least 
about  a  thousand  nemas. 

Dozens  of  Species  Found.  Often  the  nema  population  is  of  a  mixed 
character,  but  sometimes  it  is  comparatively  homogeneous.  On 

*Waverly  Press,  Baltimore,  Jan.  11,  1918. 


190  FILTER-BED  NEMAS 

one  occasion,  at  the  end  of  a  period  of  use,  I  found  ninety-six  per  cent 
of  the  nemas  to  consist  of  but  a  single  species.  About  thirty  species 
were  found  inhabiting  the  various  beds  examined,  twenty-five  species 
being  found  to  inhabit  the  beds  of  one  city.  My  observations  make 
no  pretence  of  being  exhaustive,  and  I  presume  further  research  may 
easily  double  these  numbers.  Most  of  the  species  are  of  only  occasional 
.  occurrence ;  those  figuring  prominently  in  the  activities  of  the  beds  are  only 
about  half  a  dozen  in  number,  and  of  these  not  all  are  equally  important. 

THE  MORE   COMMON  SPECIES 

Commonest  Species  Carnivorous.  Of  the  four  more  important  species, 
(1)  Mononchus  longicaudatus,  (2)  Ironus  ignavus,  (3)  Tripyla  monohystera 
and  in  a  lesser  degree  (4)  Ironus  longicaudatus,  I  have  shown  that  all 
are  carnivorous,  that  they  feed  upon  a  variety  of  living  organisms, 
and  that  no  one  of  them  confines  itself  to  a  single  kind  of  food.  Mon- 
onchus longicaudatus,  for  instance,  feeds  upon  several  species  of  nemas, 
upon  rotifers,  and  upon  a  variety  of  protozoa.  The  same  is  true  of 
Tripyla  monhystera.  In  the  struggle  among  these  filter-bed  organisms 
it  appears  that  sometimes  one  species  may  almost  annihilate  others. 
This  accounts  for  such  cases  as  that  in  which  Mononchus  longicaudatus 
constituted  ninety-six  per  cent  of  the  nema  population  of  a  bed. 

ROTATION  OF  THE  FLORA  AND  FAUNA 

Seasonal  Fluctuations.  I  know  little  about  the  seasonal  fluctuations ; 
merely  that  they  exist  and  that  sometimes  they  are  very  marked. 
For  instance,  on  January  6  samples  of  sand  were  gathered  from  various 
locations  on  a  Washington  filter-bed.  This  bed  had  been  in  operation 
about  six  months,  a  period  longer  than  in  the  case  of  any  previous 
examination  (summer  collections).  About  the  same  range  of  species 
was  found  in  this  sand  as  had  been  found  in  all  previous  experience 
taken  together,  but  the  smaller  nemas,  including  Monhystera,  were 
much  more  abundant  in  this  than  in  previous  collections,  and  seemed 
to  be  thriving.  A  large  Dorylaimus  that  had  been  extremely  rare 
in  previous  collections  was  fairly  common  in  this  January  collec- 
tion. Achromadora  minima  was  also  more  common.  Finally  there 
were  one  or  two  small  species  not  hitherto  found,  Cylindrolaimus  ob- 
tusus  and  a  Rhabdolaimus.  Whether  these  faunal  differences  were 
due  to  the  winter  season  or  to  the  long  time  the  bed  had  been  in  use 
remains  in  certain  instances  undetermined, — very  likely  some  of  them 
were  due  to  both  causes. 

Economic  Bearings.  Apart  from  seasonal  fluctuations,  there  is  a 
rotation  in  the  fauna  and  flora  incidental  to  the  management  of  the 


FILTER-BED  NEMAS  AND  PUBLIC  HEALTH  191 

beds.  Beginning  with  a  new  period  of  use,  it  appears  that  minute 
species,  e.g.,  bacteria  and  protozoa,  having  a  short  life  cycle  and  suited 
to  the  new  conditions,  first  make  their  appearance;  these  multiply 
and  become  the  food  of  succeeding  species,  which  in  their  turn  give 
place  to  others.  The  problems  presented  are  of  great  biological  interest, 
and  may  not  be  without  some  bearing  on  public  health.  Beyond 
doubt  they  have  a  more  or  less  important  relation  to  the  economical 
and  effective  management  of  the  filter-beds. 

DETERMINING  FACTORS  OF  FILTER-BED  POPULATION 

Organisms  other  than  Nemas.  Many  other  kinds  of  organisms  are 
found  in  filter-beds,  some  of  them  in  far  greater  numbers  than  the  nemas. 
Bacteria,  fungi  and  protozoa  occur,  of  course,  in  abundance,  and  are, 
I  believe,  the  organic  basis  on  which  is  built  up  the  later  animal  pop- 
ulation consisting  of  organisms  of  larger  size,  such  as  the  nemas. 
Rotifers  are  not  uncommon.  Small  oligochaetes, — earthworms, — occur, 
especially  after  long  use,  but  never  in  such  myriads  as  in  sewage.  Small 
crustaceans,  such  as  daphnia  and  cy clops,  sometimes  occur,  but  I  have 
never  seen  them  in  large  numbers.  Occasionally  aquatic  insects  are 
found.  The  filter-beds  of  each  city  present  biological  peculiarities 
dependent  upon  the  source  of  the  water  supply,  for  the  biological 
characteristics  of  filter-beds  depend  to  a  considerable  extent  on  the 
climatic  and  geological  conditions  prevalent  on  the  water-shed  from 
which  the  supply  is  drawn. 

PHYSIOLOGICAL  SIGNIFICANCE  OF  FILTER-BED  NEMAS 

Illness  from  Change  of  Water.  It  is  a  well-accepted  idea  among 
physicians,  as  well  as  laymen,  that  a  change  of  drinking-water  may 
cause  intestinal  disorders;  why  they  are  thus  caused  is  not  always  clear. 
If  the  waters  in  question  are  widely  different  in  composition,  for  instance 
one  soft  and  the  other  hard,  it  is  easy  to  understand  how  intestinal 
derangements  might  follow  a  change  from  one  to  the  other;  but  are 
the  derangements  due  to  change  of  water  always  associated  with  such 
marked  chemical  differences?  Do  not  intestinal  disturbances  follow 
changes  of  water  in  which  the  usual  tests  would  show  but  very  slight 
differences? 

Soluble  Excreta  in  Drinking-water.  Is  it  possible  that  slight  quantities 
of  organic  substances  found  in  drinking  water  and  of  a  character  as 
yet  unknown,  might,  under  some  circumstances,  exert  a  powerful 
physiological  influence?  If  this  question  be  answered  affirmatively, 
a  wide  field  of  investigation  is  opened  up  in  connection  with  potable 
waters,  and  it  is  in  this  connection  that  the  present  researches  are 


192  FILTER-BED  NEMAS 

definitely  suggestive.  The  filter-beds,  after  they  have  been  cleaned 
and  again  put  to  use,  soon  become  the  habitat  of  a  succession  of  various 
organisms,  animal  as  well  as  vegetable,  so  that  at  the  end  of  a  period 
of  use  it  is  no  exaggeration  to  say  that  the  sand  through  which  the  water 
percolates  swarms  with  them.  To  state  a  definite  case  quantitatively, 
it  has  been  shown  during  these  examinations  that  such  filter-bed  sand 
may  contain  hundreds  of  millions  of  nemas  per  acre  in  the  top  three1 
inches.  Each  of  these  nemas  is  excreting  material  of  which  the  soluble 
portions  must  pass  into  the  city's  water  supply,  and  if  in  the  course 
of  its  passage  through  the  filters,  flumes,  and  delivery  pipes  this  soluble 
matter  is  not  precipitated  or  otherwise  altered,  it  is  present  in  every 
glass  of  drinking-water. 

FLAVOR  OF  DRINKING  WATERS 

Drinking-water  Connoisseurs?  The  excreta  of  any  given  filter-bed 
organism  must  be  different  from  that  of  any  other,  and  though  the 
differences  may  be  slight  between  similar  organisms,  there  are  good 
reasons  for  thinking  that  the  differences  among  the  organisms  of  the 
filter-beds  of  different  cities  are  great  enough  to  cause  material  dif- 
ferences in  the  nature  of  their  excreta.  Such  soluble  parts  of  the  excreta 
as  pass  into  the  drinking-water  must  play  a  role  in  imparting  to  the 
water  its  flavor  and  other  qualities.  This  is  enough  to  make  one  wish 
that  we  had  connoisseurs  to  assist  us  in  the  selection  and  control  of 
drinking-water,  as  we  have  connoisseurs  in  wine  and  tea, — connoisseurs 
or  experts  capable  of  distinguishing  minute  differences  in  the  flavor  of 
drinking-waters.  At  first  thought  this  may  seem  too  fine-spun,  and  yet 
when  we  think  of  the  care  exercised  in  selecting  wines,  teas,  and  other 
beverages,  and  compare  their  actual  importance  with  that  of  drinking- 
water,  it  may  not  be  going  too  far  to  suggest  that  consideration  be 
given  to  the  possibility  of  determining  th£  qualities  of  drinking-water 
by  flavor  and  other  tests  in  addition  to  those  now  in  use.  I  think 
experienced  persons  with  a  delicate  sense  of  taste  will  bear  out  the 
statement  that  the  drinking-water  of  each  city  has  its  characteristic 
flavor.  If  half  a  dozen  glasses  of  fresh  drinking-water  could  be  assem- 
bled from  the  water  supplies  of  as  many  cities,  I  have  little  doubt  that 
a  person  with  a  delicate  sense  of  taste  wrould  be  able  to  tell  one  from 
another  blindfolded,  at  any  rate  where  the  differences  were  most 
pronounced. 

In  this  discussion  it  matters  little  that  the  amount  of  the  dissolved 
substances  thus  suggested  as  a  possible  cause  of  differences  in  the  physi- 
ological action  of  drinking-water  is  minute,  for  it  is  a  well-established 
fact  that  very  minute  quantities  of  various  substances  may  have  a  pro- 


CONTROL  OF  FILTER-BED  NEMAS  193 

found  effect  upon  the  human  organism.  Such  reflections  lead  to  the  sug- 
gestion that  the  study  of  filter-bed  organisms  is  one  that  should  be 
prosecuted  more  vigorously.  We  have  developed  a  few  excellent  chemical 
tests,  and,  so  far  as  it  goes,  an  excellent  system  for  determining  the 
bacterial  content  of  drinking-water.  Why  not  go  a  step  farther  and 
make  at  least  an  attempt  to  determine  the  nature  of  the  minute  quan- 
tities of  soluble  organic  substances  of  physiological  significance  which 
may  be  present,  and  the  origin  and  nature  of  these  substances. 

POSSIBLE  CONTROL  OF  FILTER-BED  ORGANISMS 

If  it  should  be  found  that  the  presence  of  a  particular  micro-organism 
in  filter-beds  is  deleterious,  is  it  possible  so  to  manage  the  beds 
as  to  exclude  the  micro-organism,  or  counteract  its  effect?  Already  I 
feel  sufficiently  conversant  with  some  of  the  facts  to  predict  that  such 
control  will  prove  feasible,  at  least  in  some  instances.  In  the  case  of 
Mononchus  longicaudatus  for  instance,  as  soon  as  we  know  the  natural 
distribution  of  the  Mononchus;  its  relationship  to  the  seasons  of  the 
year,  if  it  has  any  significant  relationship  of  that  kind;  the  period  of 
its  life  cycle;  its  rate  and  method  of  reproduction;  its  food;  its  enemies; 
then,  almost  beyond  doubt  we  shall  be  able  to  suggest  means  for  its 
control.  So  with  other  organisms. 

To  secure  a  reliable  filter-bed  census  it  is  necessary  to  examine  the 
sand  as  soon  as  collected.  After  a  short  period  under  laboratory  con- 
ditions the  population  begins  to  change:  e.g.,  sand  which  at  the  time 
it  was  removed  from  the  bed  contained  many  specimens  of  Mononchus 
and  a  few  of  Ironus  ignavus,  after  ten  days  yielded  no  Mononchus,  though 
it  continued  to  yield  Ironus,  and  in  addition  a  few  adult  specimens  of 
Tripyla  and  Monhystera, — differences  no  doubt  due  in  part  to  the  fact 
that  in  stagnant  collections  Mononchus  longicaudatus  is  subject  to  the 
attacks  of  a  variety  of  fatal  diseases  caused  by  fungi  and  microbes. 

NEMAS  A  CLUE  TO  THE  FLOW 

Nemas  Unequally  Distributed  in  Beds.  The  distribution  of  organisms 
in  filter-beds  is  not  uniform.  For  example,  if  a  series  of  samples  be  col- 
lected, one  each  from  near  the  main  drain-pipe,  near  a  lateral,  between 
the  laterals,  and  at  the  margin  of  the  bed,  the  numbers  and  kinds  of 
nemas  will  be  found  to  differ  in  the  various  samples.  This  unequal 
distribution  is  doubtless  a  function  of  the  flow  of  the  water,  for  where 
the  flow  is  rapid  the  biological  environment  differs  from  that  where  it 
is  slower;  there  is  a  greater  supply  of  oxygen,  a  greater  supply  of  water- 
soluble  food,  and  a  greater  supply  of  such  free  micro-organisms  as  may 
pass  between  the  grains  of  sand.  It  follows  that  to  some  extent  the 


194  FILTER-BED  NEMAS 

fauna  and  flora  of  filter-bed  sand  may  be  made  a  criterion  of  the  rate 
and  nature  of  the  filtration. 

The  general  appearance  of  the  sand  in  any  particular  part  of  the  bed  is 
a  clue  to  the  rate  and  nature  of  the  filtration  there,  but  this  rough  method 
is  capable  of  refinement  through  the  aid  of  a  biological  census.  The 
difficulty  is  we  do  not  yet  know  what  significance  to  attach  to  the 
presence  or  absence  of  particular  species.  Should  an  attempt  be  made 
to  devise  and  apply  such  a  method,  it  might  be  found  that  the  presence 
or  absence  of  a  few  species  would  constitute  a  sufficient  test. 

PARTIAL  LIST  OF  THE  NEMAS  FROM  AMERICAN  SLOW  SAND 
FILTER-BEDS* 

Achromadora  minima  Cobb Washington,  D.  C.  Mononchulus  ventralis  n.  g.,  n.  sp. 

Actinolaimus  radiatus  Cobb...  .Washington,  D.  C.  Washington,  D.  C. 

Aphanolaimus  ? Philadelphia  Mononchus  longicaudatus  Cobb 

Apheltnchus  ep Pittsburg  Washington,  D.  C. 

Atylenchus  sp New  Bedford  ,,          ,  „,..    .  .   ,. 

Cephalobustp Philadelphia  Mon°™h™  *» Philadelplua 

Cylindrolaimus  obtusus  Cobb... Washington,  D.  C.  Plectus  clrratus  Bastian Washington,  D.  C. 

Dorylaimus  fecundus  Cobb Washington,  D.  C.  Prismatolaimus  sp Philadelphia 

Dorylaimus  sp Washington,  D.  C.  Rkabditis  sp Philadelphia 

Dorylaimus  sp Philadelphia  Rhabdolaimus  sp Washington,  D.  C. 

Dorylaimun  sp Philadelphia  Spilophora  sp Harrisburg 

Dorylaimus  Bp Washington,  D.  C.  Teratocephalus  sp Pittsburg 

lota  simile  n.  sp  Washington,  D.  C.  Trilobus  longus  Leidy Philadelphia. 

Ironus  americanus  Cobb Philadelphia  THpyla  monohystera  de  A/an ...  Washington,  D.  C. 

Ironus  ionavus  Bastian Washington.  D.  C.  Tylencholaimus  sp ^^  Bethlehem, 

Ironus  longicaudatus  de  M an. .  .Washington,  D.  C.  p.      , 

Monhystera  subfiliformis  n.  sp . .Washington,  D.  C. 

Monhystera  dispar  Bastian Washington,  D.  C.  Tylenchus  filiformu  Butschh  (?) 

Monhystera  sp Philadelphia  Washington,  D.  C. 

Monhystrella  plectoides  n.  subg.,  n.  ep.  Tylenchus  sp Philadelplua 

Washington,  D.  C.  Xiphinema  americanum  Cobb Philadelphia 

*  The  larger  number  of  species  from  the  Washington  beds  is  due  to  the  examination  of  a  larger  num- 
ber of  samples  than  from  beds  elsewhere.  The  more  important  of  these  species  are  described  below. 
The  drawings  are  from  nature  and  were  made  under  the  author's  personal  supervision  by  Mr.  W.  E. 
Chambers. 

MONONCHUS  Bastian  1865 

1.  Mononchus  longicaudatus  Cobb  (See  p.  161).  The  feeding  habits  of  Monon- 
chus are  distinctly  different  from  those  of  either  of  its  frequent  companions, 
Tripyla  and  Ironus.  In  capturing  food  Mononchus  depends  largely  upon  the 
grip  of  its  powerful  jaws.  Tripyla  depends  upon  its  agility  and  its  flexibility, 
and  possibly  coils  itself  about  its  victim,  after  the  manner  of  a  boa  constrictor. 
Mononchus  and  Tripyla  bolt  their  food,  but  Ironus  feeds  in  an  entirely  different 
way;  attaching  its  lips  to  its  food,  it  rips  a  hole  in  the  external  layers  by  the 
outward  stroke  of  its  three,  extremely  sharp,  radially  acting  onchi.  As  these 
move  forward  their  points  move  outward,  and  two  or  three  such  movements  serve 
partially  to  imbed  the  head  of  the  Ironus.  It  would  appear  that  then  the  more 
or  less  fluid  parts  only  are  imbibed,  for  the  contents  of  the  intestine  of  Ironus 
hardly  ever  present  optically  identifiable  substances.  It  is  manifest,  however, 
that  the  contents  of  the  intestine  are  animal  in  character,  and  so  it  seems  beyond 
reasonable  question  that  Ironus  is  carnivorous.  I  have  never  found  the  con- 
tents of  the  intestine  to  respond  to  the  starch  test. 


MONONCHULTJS  VENTRALIS 


195 


Intro,  vilam  staining  shows  the  existence  of  a 
dorso-ventral  physiological  differentiation  in  the 
intestine  of  Mononchus  longicaudatus. 

Renette.  When  this  well-known  mononch  was 
stained  inlra  vitam  with  trypan  blue,  the  ampulla 
and  a  short  portion  of  the  duct  of  the  renette  was 
so  distinctly  seen  as  to  leave  almost  no  shadow  of 
doubt  that  this  portion  of  the  renette  structure 
is  normal.  I  am  inclined  to  think  that  the  duct 
soon  takes  a  lateral  turn,  and  possibly  becomes 
connected  with  the  lateral  field;  thus  far  it  has  not 
been  possible  to  follow  it  more  than  a  distance 


mrfi 
p/i.. 


Fig.     1.    Man- 
chulus  ventralis, 


/*' 


, 
rl  or  til 


mil 


a  very  interesting 
nema,  found  in 
the  Washington  irltirtil 
filter-beds.  The 
lateral  fields  are 
shown  with  great 
clearness;  they  fm 
are  made  up  of 
about  three  rows 
of  cells,  d  ar  lat, 
each  cell  with  an 
egg-shaped  nu- 
cleus, nd  ar  lat. 
The  intestinal 
nuclei,  of  about 
the  same  size,  are 
shown  darker. 
Oesophageal 
glands,  sal,  as  in 
Mononchus.  The 
small  posterior 
gonad,  appar- 
ently serving  as 
a  testis,  is  shown 
at  1st.  Nearly  the 
whole  of  the  tostis 
is  shown  in  the  il- 
lustration. The 
spinneret  is  unus- 
ually large,  and 
gives  us  for  the 
first  time  some 
clue  to  the  struc-  w,,,.!,/ 
ture  and  me-  a 
chanics  of  this 
organ.  The  de- 
tailsaremorefully 
illustrated  in  Fig. 
2.  For  abbrevia- 
tions see  p.  212. 


am  of 


n-lm-liil 
//////  m . 
mr  am . 


about  equal  to  the  radius  of  the  nsck,  so  that  the 
size  and  structure  of  the  glandular  part  remain 
unknown.  nlylcdl. 

MONONCHULUS  gen.  nov. 

Characters.  Possessing  the  form  and  general 
appearance  of  Mononchus,  but  having  the  spinneret 
on  the  ventral  side  of  the  tail  near  the  terminus, 
and  the  pharynx  smaller  and  narrower  with  thicker 
walls,  and  with  forward  pointing  onchi  or  teeth,  of 
which  a  subventral  one  dominates.  The  labial 
papillae  are  smaller  than  is  usual  in  Mononchus,  in  fact  are  barely  visible. 


196  FILTER-BED   NEMAS 

The  entire  pharynx  is  about  twice  as  long  as  the  cavity  bearing  the  onchi,  but 
the  posterior  part  is  narrower  and  somewhat  obscure. 

Anterior  gonad  reflexed.  Posterior  gonad  outstretched,  very  small,  producing 
spermatozoa.  The  development  of  the  oocytes  follows  about  the  same  course  as 
that  of  the  spermatocytes,  which  they  resemble  to  a  certain  extent,  though 
they  are  larger.  Occasionally  the  oocytes  so  closely  resemble  the  spermat- 
ocytes that  it  is  rather  difficult  to  make  a  clear  distinction.  The  very  youngest 
stages  of  the  female  gonad  have  not  been  seen,  but  in  the  youngest  stages  ob- 
served there  were  no  indications  of  spermatozoa; — yet  at  the  same  time  sper- 
matozoa were  developing  in  the  minute  posterior  straight  gonad. 

2.  Mononchulus  ventralis  n.  sp.  ^ ^7  ^ f^j  trs'1  •  The  thick 
layers  of  the  transparent,  colorless,  naked  cuticle  appear  to  be  devoid  of  any 
but  the  very  finest  of  transverse  striae;  but  longitudinal  striations  are  visible 
throughout  the  length  of  the  body.  Six  rather  thoroughly  amalgamated  lips 
of  considerable  thickness  arch  together  over  the  pharynx  and  normally  nearly 
close  the  mouth  opening.  There  are  six  slightly  spreading  inconspicuous  papillae 
scarcely  interfering  with  the  rounded  contour  of  the  front  of  the  head;  in  addi- 
tion, surrounding  the  mouth,  there  are  six  forward  pointing  papillae.  There 
are  no  eye-spots.  Very  inconspicuous  amphids  occur  opposite  the  middle  of  the 
largest  pharyngeal  tooth  in  the  form  of  small  semi-circumferences  opening  back- 
ward and  having  a  breadth  about  one-fifth  as  great  as  that  of  the  corresponding 
part  of  the  head.  The  anterior  main  thick-walled  portion  of  the  pharynx  is 
about  as  long  as  the  head  is  wide.  When  the  pharyngeal  organs  are  at  rest 
this  front  cavity  is  comparatively  well  filled  by  the  large,  acute,  forward 
pointing  right  submedian  tooth.  There  are  two  other  teeth,  a  small  dorsal,  for- 
ward pointing  tooth  having  its  apex  near  the  middle  of  the  pharynx,  and  an  ex- 
ceedingly minute  inward  pointing  tooth,  or  spur,  in  the  left  submedian  portion 
of  the  cavity  near  the  base.  Opposite  the  anterior  portion  of  the  main  tooth 
the  walls  of  the  pharynx  are  armed  with  several  dozens  of  minute,  rasp-like 
teeth  or  denticles. 

Close  scrutiny  of  that  part  of  the  wall  of  the  pharynx  immediately  behind 
the  rasp-like  area  discloses  that  it  is  transversely  striated  to  near  the  base. 
These  pharyngeal  striae  can  be  seen  only  with  the  highest  powers  of  the  micro- 
scope under  favorable  circumstances.  Behind  this  anterior  portion  of  the 
pharynx  is  a  narrower,  unarmed  portion,  of  equal  length,  making  the  total  length 
of  the  pharynx  about  twice  as  great  as  the  diameter  of  the  head.  The  cells  of 
the  thick  walled,  narrow-lumened  intestine  contain  scattered  brownish  granules. 
There  are  three  unicellular  caudal  glands;  two  opposite  each  other  immediately 
behind  the  anus,  and  a  third,  more  or  less  dorsally  located,  behind  and  between 
the  first  two  but  emptying  through  a  submedian  ampulla  and  hence  really  sub- 
median.  The  single  reflexed  ovary,  except  when  pushed  forward  by  the  presence 
of  an  egg  in  the  uterus,  reaches  nearly  back  to  the  vulva. 

Habitat:  This  interesting  digonic  species  has  been  found  in  peat  soil,  west 
of  Fort  Lauderdale,  Fla.,  along  a  canal  for  drainage  of  land  formerly  covered 
with  water,  and  at  Miami,  Fla.;  in  the  sand  of  the  filter  beds  at  Washington,  D. 
C.;  and  also  in  the  Potomac  River. 

A  species  that  appears  to  belong  to  the  genus  Mononchulus  is  described  by 
Daday  under  the  name  Prismatolaimus  nodicaudatus,  n.  sp.,  in  his  "Mikro- 
skopische  Siisswasserthiere  aus  Deutsch  Xeu  Guinea." 


MECHANICS   OF  THE    SPINNERET 


197 


sub  ait 


STRUCTURE  OF  THE  SPINNERET 

I  am  not  aware  that  anyone  has  ever  attempted  to  explain  the  mechanism  of 
Ihe  spinneret  of  nemas.  Manifestly  the  flow  of  the  caudal  secretion  is  controlled 
at  will.  Watching  this  operation  as  performed  by  a  free-living  nema,  one  is 
forcibly  reminded  of  the  facility  with  which  spiders  regulate  the  operation  of 
their  spinnerets,  and,  as  in  spiders,  so  in  nemas,  there  must  be  a  definite  con- 
trollable mechanism  for  performing  these  operations.  The  structure  of  the 
spinneret  in  Mononchulus  venlralis  may  at  least  suggest  the  mechanical  prin- 
ciples exemplified. 

The  Needle-Valve.  As  a  rule  the  nema  spinneret  is  so  extremely  minute  that 
its  details  cannot  be  deciphered.  In  Mononchulus  ventralis  the  spinneret  is 
relatively  large  and  its  elements  more  or  less  resolvable,  but  since  it  is  ventral 
in  this  species  instead  of  terminal,  as  is  usual,  its  form  may  not  be  entirely  typical. 
In  M.  ventralis  we  find  the  duct  of  the  spin- 
neret to  end  externally  in  a  conical  depres- 
sion near  the  end  of  the  tail.  This  conical 
depression  leads  to  a  short  oblique  tube 
terminating  internally  at  the  valve  of  the 
spinneret,  vlv-vlv,  Fig.  2.  The  valve  belongs 
to  the  class  known  as  needle-valves,  and  the 
needle,  if  such  it  be  called,  is  an  acute,  fusi- 
form affair,  duplex  in  cross  section,  and 
nearly  half  as  long  as  the  terminus  of  the 
tail  is  wide.  It  is  placed  at  an  angle  of 
about  45  degrees  with  the  axis  of  the  tail,  and 
while  its  acute  free  distal  end  lies  loose  in  a 
cavity  of  obverse  mold,  its  more  or  less 
cephalated  proximal  end  is  connected  with 
the  dorsal  side  of  the  tail  by  means  of  oblique 
muscular  fibres.  The  proximal  part  of  the 
valve  is  located  in  the  midst  of  a  vesicle  (?) 
to  the  dorsal  side  of  which  its  proximal  ex- 
tremity seems  to  be  attached;  the  embryo- 
logical  development  has  not  been  investi- 
gated, but  conceivably  the  needle  is  formed 
by  an  invagination  of  the  wall  of  the  "vesi- 
cle." Into  the  base  of  the  more  or  less 
ellipsoidal  "vesicle"  the  ducts  of  the  caudal 

... 
glands  empty.     1  he  operation  of  the  needle-    part  of   the   spindle-shaped 

valve  is  now  easily  understood.  The  internal 
body  pressure  will  of  itself  keep  the  needle- 
Valve  closed.  Contraction  of  the  muscular 

fibres  already  described  serves  to  pull  the 

needle  loose  from  the  mouth  of  the  valve, 

and  so  permit  an  outflow  of  the  secretion.    The  "needle"  is  composed  of  two 

elongated,  ceratinous  lateral  elements  joined  side  by  side,  and  the  orifice  of  the 

valve  is  composed  of  three  elements,   disposed  in  the  form  of  a  hollow  cone 

about  the  distal  half  of  the  needle. 

Nervous  Apparatus  of  Valve.  Most  of  the  foregoing  features  are  shown  in 
Fig.  2.  Necessarily  the  apparatus  is  supplied  with  the  appropriate  sensory  and 
motor  nerves.  The  details  of  these  latter  have  not  yet  been  made  out  with 


x2ooo  -::."."!„ <l jar  aS 

Fig.  2.  Spinneret  of  Mononchulus  ven- 
tralis, with  coagulated  secretion  attached. 
The  valve  is  partly  open  and  the  secretion 
is  pouring  out.  The  three  ampullae  empty 
into  a  common  space  round  the  proximal 
jpindle-shaped  valve-plug, 


pulled  open  by  the  muscle,  msc  vlv.    All 


198  FILTER-BED   NEMAS 

certainty;  however,  innervated  papillae  occur  near  the  terminus, — doubtless 
tactile  in  function.  The  shortest,  i.e.,  dorsal,  unpaired  caudal  gland  empties 
through  a  dorsally  left  submedian  duct.  Of  the  two  longer  and  paired  glands, 
one,  the  left  submedian,  empties  through  a  ventral  ampulla,  while  the  other 
empties  through  a  dorsally  right  submedian  one;  the  details  of  the  debouchment 
remain  somewhat  obscure  and  no  attempt  has  been  made  to  indicate  all  of  them  in 
the  illustration.  The  three  pores,  however,  are  just  in  front  of  the  "equator"  of 
the  valve. 

Digonic.  This  species  presents  the  unusual  peculiarity  for  an  hermaphroditic 
nema  of  developing  its  ova  in  one  gone,  and  its  sperm  in  another  gone  of  much 
smaller  size, — in  a  word  is  digonic.  So  great  is  the  disparity  between  these  two 
branches  of  the  sexual  apparatus  that  at  first  glance  one  almost  inevitably  con- 
cludes that  the  very  small  posterior  branch  is  a  mere  functionless  vestige. 
A  careful  examination  seems  to  prove  that  only  ova  are  produced  in  the  anterior 
branch,  while  the  very  small  outstretched  posterior  gonad  functions  as  a  testis; 
the  evidence  for  this  latter  conclusion  being  the  occurrence  of  spermatozoa  and 
spermatocytes  in  small  numbers  arranged  in  the  order  to  be  expected  if  the 
organ  were  a  small  gonad  devoted  solely  to  the  production  of  sperm.  The  cells 
in  this  minute  gonad  are  so  few  that  their  precise  order  is  not  a  striking  feature, 
and  yet  an  examination  of  a  series  selected  from  among  individuals  in  which  the 
ova  in  the  anterior  gonad  are  still  quite  young  and  small,  enables  one  to  demon- 
strate that  the  cells  near  the  blind  end  of  the  small  gonad  correspond  in  structure 
with  primary  spermatocytes,  and  that  the  succeeding  cells,  sometimes  as  few  as 
two  to  three  in  number,  represent  successive  steps  in  the  development  of  the 
spermatozoa.  Occasionally  one  finds  here  a  pair  of  gonic  cells  lying  side  by  side, 
each  containing  about  six  chromosomes,  practically  as  definite  as  those  to  be  seen 
in  the  testes  of  male  individuals  of  typical  free-living  amphigonic  nemas.  Often 
the  perfected  spermatozoa  appear  not  to  exceed  eight  to  twelve  in  number. 
There  is  an  obscure  tendency  for  them  to  be  located  in  groups  of  four,  such  as 
should  exist  if  they  were  produced  in  situ  in  quartets  in  the  manner  character- 
istic of  the  spermatozoa  of  nemas.  Once  an  egg  was  observed  containing  near 
its  equatorial  periphery  a  body  corresponding  in  size  and  staining  properties  to 
one  of  the  spermatozoa  to  be  seen  free  in  the  uterus.  The  nucleus  of  this  egg 
showed  signs  of  being  affected  by  the  presence  of  the  spermatozoon,  though  it 
appeared  not  yet  to  have  produced  polar  bodies.  All  these  appearances  are  in 
harmony  with  the  supposition  that  the  posterior  branch  of  the  sexual  apparatus, 
small  as  it  is,  functions  as  a  testis. 

TRIPYLA  Bastian  1865 

3.  Tripyla  monohystera  de  Man.  /o  [79  T.  271 — T7?1'4"""  Few  nemas 
are  more  agile  than  this.  Its  movements  are  extremely  rapid,  especially  those  of 
the  head  end.  It  is  unusually  flexible,  coiling  and  uncoiling  all  parts  of  its  body 
with  great  rapidity.  It  is  of  a  restless  disposition,  at  least  so  appears  when 
brought  under  the  microscope  for  examination. 

I  have  often  seen  this  Tripyla  attach  itself  to  glass  and  then  exhibit  the  evolu- 
tions characteristic  of  nemas  possessing  well  developed  spinnerets,  but  in  spite 
of  careful  examination  of  living  specimens,  and  specimens  preserved  both  in 
glycerine  and  balsam,  I  have  seen  no  definite  traces  of  caudal  glands.  The 
cephalic  setae  are  segmented  and  consist  of  two  or  more  joints. 

Harbors  a  Parasite.  Tripyla  monohystera  of  the  Washington  filter-beds  often 
contains  what  appears  to  be  a  peculiar  spherical  parasite.  The  parasites  (?) 


TRIPYLA   MONOHYSTERA 


199 


seem  usually  to  gain  entrance  to  the  body  at  or  near  the  caudal  extremity,  for 
in  almost  all  cases  where  their  number 
is  few  they  are  confined  to  the  tail. 
See  Fig.  3.  Thence  they  seem  to  work 
their  way  forward,  especially  along  the 
lateral  fields,  so  that  finally  they  may  oc- 
cur throughout  the  length  of  the  body 
in  hundreds  of  thousands.  These  ob- 
jects are  extremely  minute  and  can  be 
satisfactorily  examined  only  with  the 
aid  of  the  highest  powers  of  the  micro- 
scope. At  first  sight  they  appear  to  be 
crescent  shaped,  a  deception  due  to  their 
peculiar  refractive  properties.  Careful 
focusing  shows  that  the  greater  portion 
of  the  sphere,  an  eccentric  portion,  is 
but  slightly  refractive.  The  remaining 


Fig.     3.     Tripyla 
This  active,  voraciov 


monohyslera. 
s  little  nema 

is  very  common  in  filter-beds. 
Often  the  remains  of  several  other 
nemas  are  to  be  found  in  its  intes- 
tine. The  specimen  figured  had 
been  feeding  on  a  variety  of  micro- 
zoa.  To  be  seen  in  the  intestine 
are  a  nema,  nematod  ing:  the 
"gizzard"  of  a  rotifer,  rot  ing;  and 
a  number  of  protozoa,  ing.  The 
egg  shown  has  just  received  one  of 
the  syngonic  sperm  cells  sp,  and  has 
thrown  off  the  first  polar  body,  corp 
plr  I.  The  beginning  of  a  sporo- 
zopn  (?)  infestation  is  shown  in  the 
tail,  par.  The  renette  of  this  nema 
(ran;  ex  p)  has  hitherto  remained 
unknown.  An  organ  of  consider- 
able size,  but  of  unknown  signifi- 
cance, org  ?,  is  also  now  for  the  first 
time  shown  to  exist  in  the  neck. 
For  abbreviations  see  p.  212. 


mini/nil  IIHJ 
niin  inl 
nclint 
nclint 
dint 
ijniinlL 
"iH  I 
ia 


portion  is  more  easily  seen,  and,  when 
it  comes  into  view  in  optical  section, 
presents  the  contour  of  a  crescent; — is 
therefore  in  reality  bowl- shaped.  I  have 
made  no  serious  attempt  to  classify  these 
objects  and  can  only  suggest  that  we 
have  here  a  new  sporozoon.  If  so  it 
may  be  the  cause  of  a  serious  disease  of 
the  nematode;  often  10  to  20  per  cent 
of  the  individuals  appear  to  contain  it. 
In  some  collections  it  occurs  in  practi-  ^ 
cally  every  individual.  •*"* 

Nemativorous.     Nematodes  having    a     nd  mt 
plain    oesophagus,     such    as     Tripyla,     ^ 
Mononchus,  and  Monhystera,  often   ex- 
hibit a  marvelous  capacity  for  swallow- 
ing relatively  large  objects.    Some  spe- 
cies of  Monhystera  are  able  to  swallow  diatoms  one-half  to  two-thirds  as  wide  as 
themselves,  and  one-fifth  to  one-sixth  as  long.      Tripyla  monhystera  is  rather 


200 


FILTER-BED   NEMAS 


The  .     excret 

pore  is  at  the  li 
The      submedi 

em'pty1'  oppos 


remarkable  in  this  respect.  It  has  lit- 
tle difficulty  in  swallowing  nemas  half 
as  wide  as  itself;  and  the  partly  di- 
gested remains  of  several  such  may 
sometimes  be  seen  in  its  intestine. 
(See  Fig.  3.) 

IRONUS  Bastian  1865 
4.  Ironus  longicaudatus  de  Man. 

.!»  _  7.1         15.        •'•36"3     66. 
/1.6  1.9  2.  2.2  1.2 

As  regards  the  pronounced  dorso- 
ventral  differences  in  the  intestine  of 
Ironus  longicaudatus,  when  specimens 
of  this  species  are  stained  in  acid  car- 
mine it  is  noticeable  that  the  large 
granules  characteristic  of  the  dorsal 
side  take  the  stain.  From  an  exami- 
nation of  living  specimens  one  would 
think  these  granules 
probably  fatty  in  their  leJkt./JS 
nature.  The  fact  that 

.11 
they    Stain     as     they     do 

seems    to     exclude    this 
supposition. 

No  Sperm  keen.  In  back.  The 
spite  of  very  careful  ex-  &£*  o 
amination  I  was  unable 
to  discover  spermatozoa 
in  the  females  of  this 
species.  Nevertheless  I 
am  strongly  inclined  to 
think  that  further  in- 
vestigation will  reveal 
the  presence  of  sperma- 
tozoa, and  show  that  this 
species  also  is  syngonic. 
I  have  seen  no  males. 

I     believe     the    food- 
habits  of    Ironus   longi- 
caudatus to  be  much  the 
same  as  those  of  Ironus 
ignavus,  but  having  had 
less   opportunity    to  in-    ^ 
vestigate    them   I    have    '* 
fewer  data    from  which    *" 
to  form  an  opinion.  •» 

Habitat:  Washington  *» 
filter-beds;  sometimes  »v 
abundant.  Quite  active,  «•;/» 


ay' 
rail 

xl.ii 


very  much  from 
thevantral. 


tfjer 

r!  a 


EVIDENCE   THAT   IRONUS   IS   CARNIVOROUS  201 

5.  Ironus  ignavus  Bastian.  TiTi  TI  [76 ~Ti iTT  2'7  "'  The  pharyngeal 

onchi  are  tissue  tearers.  The  three  onchi  of  Ironus  ignavus  are  of  unequal  form 
and  size.  At  first  glance  they  appear  equal,  but  even  when  the  onchi  are  drawn 
in  and  the  head  viewed  in  profile  it  is  sometimes  possible  to  see  that  the  dorsal 
onchus  differs  from  the  other  two  in  being  duplex.  When  the  onchi  are  exserted 
the  expansion  necessary  to  this  operation  throws  the  two  apices  of  the  dorsal 
onchus  wide  apart,  and  they  can  then  with  ease  be  brought  separately  into 
focus.  A  front  view  of  the  head  also  emphasizes  this  double  structure  of  the 
dorsal  onchus.  Either  half  of  this  onchus  when  seen  in  profile  seems  to  be  of 
almost  exactly  the  same  size  and  contour  as  one  of  the  submedian  onchi.  The 
action  of  the  onchi  in  Ironus  is  like  that  in  some  species  of  Diplogaster,  of  most 
species  of  Axonolaimus  and  of  one  or  two  other  marine  genera,  and  is  the  exact 
reverse  of  that  of  the  onchi  of  Enoplus  and  its  relatives.  The  outward  action 
of  the  onchi  in  Ironus  is  adapted  to  tearing  open  the  tissues  upon  which  it  feeds, 
the  fluid  and  semi-fluid  portions  of  which  are  then  imbibed.  In  harmony 
with  this  is  the  liquid  or  finely  divided  character  of  the  contents  of  the  intestine 
in  Ironus.  Enoplidae,  on  the  other  hand,  bolt  their  food.  The  movements 
of  the  onchi  do  not  appear  to  be  so  quick  as  those  of  the  onchi  of  Diplogaster. 
The  outward  throw  and  return  occupied  about  one-quarter  second  in  a  specimen 
which  though  stained  intra  vitam  with  neutral  red,  yet  appeared  to  be  as  active 
as  the  average  living  specimen. 

Characteristic  Intestinal  Crystals.  The  doubly  refractive  crystals  found  in 
the  intestinal  cells  of  Ironus  are  different  from  those  found  in  certain  Rhabdites,  to 
which  I  have  given  the  name  Rhabditin.  The  doubly  refractive  crystals  of  Ironus 
are  not  spherical, — on  the  contrary  are  distinctly  angular  in  contour  and  have  a 
definite  polyhedral  form.  These  doubly  refractive  bodies  are  absent  from  the 
anterior  part  of  the  intestine  for  a  distance  about  equalling  half  the  length  of  the 
neck,  indicating  a  different  physiological  condition  here.  Some  of  the  intestinal 
cells  are  very  distinctly  specialized.  (See  Fig.  5.) 

Carnivorous.  The  following  are  strong  reasons  for  regarding  Ironus  as  car- 
nivorous; (1)  Recognizable  plant  remains  are  rarely  if  ever  found  in  the  intestine. 
(2)  Ironus  abounds  in  places  where  there  is  little  plant  food  of  any  kind,  but  where 
animal  food  is  plentiful.  (3)  The  peculiar  mouth  parts  can  hardly  be  ex- 
plained in  any  other  way  than  by  supposing  them  to  be  special  organs  for  rip- 
ping open  tissues  of  the  food,  and  the  only  filter-bed  plants  that  could  furnish 
adequate  food  for  Ironus  are  entirely  too  small  to  be  operated  upon  by  these 
mouth  parts. 

A  very  noticeable  feature  in  the  development  of  the  eggs  of  Ironus  ignavus 
is  the  appearance  in  the  ripening  ova  of  numerous  protoplasmic  structures  which 
stain  rather  strongly  in  acid  carmine.  Toward  a  dozen  of  these  structures 
may  be  seen  in  the  full  grown  ovum  when  about  to  turn  and  pass  into  the  uterus. 
The  younger  ovum  immediately  following  it  also  shows  these  same  structures, 
more  closely  packed  together,  but  of  about  the  same  size.  After  the  egg  has 
passed  into  the  uterus  these  bodies  sometimes  completely  disappear. 

Newly  Discovered  Organs.  Among  the  numerous  new  facts  here  brought  to 
light  in  connection  with  Ironus  none  appear  more  interesting  than  the  pro- 
nounced dorso-ventral  differentiation  of  the  intestine.  In  both  ignavus  and 
longicaudatus  this  differentiation  is  pronounced,  especially  in  the  latter,  where 
from  one  end  of  the  intestine  to  the  other  the  difference  in  structure  between  the 
dorsal  and  ventral  sides  is  very  striking.  In  ignavus  the  same  quality  of  dif- 


202 


FILTER-BED    XEMAS 


f  erentiation  occurs, 
but  the  cells  having 
the  coarser  struc- 
ture are  more  scat- 
tered. They  never- 
theless are  here 
also  commonly  dor- 
sal or  sub-dorsal. 

What  seems  to 
be  a  very  long  and 
narrow  tubular  or- 
gan (org  f)  exists 
in  ignavus.  I  have 
been  unable  to  de- 
termine the  func- 
tion of  this  inter- 
esting organ.  The 
mycelium  of  vari- 
ous parasitic  fungi 
is  not  altogether 
uncommon  in  the 
bodies  of  fresh 
water  nemas,  and 
sometimes  presents 
highly  deceptive 
appearances,  but  it 
.  did  not  seem  possi- 
ble to  me  that  this 
tubular  structure 
could  be  other  than 
an  integral  part  of 
the  Ironus. 

It  is  interesting 
to  note  that  the 
most  common  spe- 
cies of  Ironus  in 
American  filter- 
beds  are  identical 
with  those  of  Eu- 
rope. Ironus  igna- 
vus is  widely  spread 
inthe United  States, 
as  I  have  collected 
it  from  spring,  lake 
and  river  waters  of 
many  of  the  north- 
ern states,  from  the 
Atlantic  as  far  west 
as  Colorado  and 
from  widely  vary- 
ing altitudes. 


Fig.  5.    It 


.TI&.  a.     ±1  c//t««  lynuvux.     Jiiiure-  fjfj  v 

tory  pore  and  salivary  glands  as  in  /"¥*' 

longicaudatus,   q.   y.    The  differ-  '«'•»/    ,• 
entiation   of  the  intestinal   cells  , /* 

though    marked   is    not   so    pro-  «™  /* 
nounced     as     in     longicaudatus. 

Common  in  filter-beds.  See  p.  212.  /**'JH/  «• 


6  Ib  Ht 


MONHYSTRELLA 


203 


Fig.  6.  Monhyslrella  plec- 
toides  n.  subg.  n.  ep.  For  some 
distance  in  front  of  the  nerve- 
ring  the  oesophagus  is  dis- 
tinctly though  slightly  altered. 

A  critical  review  of  the  Mon- 
hysteras  so  far  discovered  and 
described  will  undoubtedly  re- 
sult in  the  establishment  of  a 
number  of  fairly  well  defined 
groups,  some  of  subgeneric 
rank,  some  of  generic.  The 
divisions  may  be  made  on  the 
basis  of  the  anatomy  of  the 
male  organs  as  well  as  on  that 
of  the  mouth  parts.  These 
anatomical  differences  are  the 
outward  expression  of  differ- 
ences in  food  habits,  and  of 
special  activities  due  to  differ- 
ences in  habitat.  The  Mon- 
hysteras  constitute  a  hu_ 
group,  of  considerable  biologi- 
cal significance.  Some  species 
are  specially  adapted  to  stud- 
ies of  problems  in  genetics. 
The  mode  of  development  of 
the  spermatozoa  of  certain 
species  is  worthy  of  study. 


Ol  A. 

(/it., 
mui-int. 
him  at. 

nil  . .  . 
at  tut 

inn  or. 
mam. 

mw  mi 
tty  fir 
it 
nl 


rim 


lit       MONHYSTRELLA  subg.  nov. 


Subgeneric  characters.  Has  the 
general  form  and  appearance  of 
Monhystera,  but  differs  in  the  fol- 
lowing respects:— The  pharynx  is 
more  elongated,  somewhat  resem- 
bling that  of  Cylindrolaimus,  but 
tapers  slightly.  The  oesophagus 
is  not  quite  of  uniform  diameter, 
in  this  respect  somewhat  resem- 
bling that  of  Plectus  in  the  ante- 
rior part,  but  with  all  the  varia- 
tions less  pronounced,  so  that,  at 
first  glance,  the  oesophagus  seems 
to  be  rather  uniform  in  structure 
from  the  pharynx  backward  to  the 
cardiac  swelling.  There  is  a 
rather  distinct  pyriform  cardiac 
swelling,  with  clear  indications 
of  the  presence  of  glands  among 
its  muscular  tissues.  One  or  two 
problematical  unicellular  organs 
exist  in  the  lateral  fields  on  each 
side  of  the  body  some  distance 
in  front  of  the  anus.  Otherwise 
very  much  as  in  Monhystera. 
Possibly  Monhystera  bulbifera  de 
Man  belongs  to  this  sub-genus. 

6.  Monhystrellaplectoidesn.  sp. 

1.2          10.  17.      '«-44.  65. 

i75  274  t76 371 ITT 
The  rather  thin,  transparent, 
colorless  cuticle  is  traversed  by 
exceedingly  fine  transverse  striae, 
resolvable  only  with  high  powers 
under  most  favorable  conditions. 
The  thin-shelled  eggs  appear  to 
be  deposited  before  segmentation 
begins. 

Habitat:  Sand,  Washington 
filter  beds;  uncommon.  Nemas 
of  the  character  represented  by 
Monhystrella  and  Monhystera  are 
largely,  if  not  entirely,  vegeta- 
rian. As  a  rule  they  are  not 
abundant  in  covered  slow  sand 
filter  beds.  On  one  occasion, 
however,  after  a  long  period  of 
winter  use,  I  found  such  nemas 
to  be  fairly  abundant. 


204  FILTER-BED    NEMAS 

They  appeared  to  have  been  feeding  upon  bacteria  and  other  similar  micro- 
phytes. Monhysteras  are  more  common  in  open  filter  beds  and  in  reservoirs, 
where  they  appear  to  feed  principally  on  green  unicellular  algae,  which  naturally 
do  not  flourish  in  covered  filter  beds,  since  sunlight,  direct  or  diffused,  is 
necessary  to  their  growth. 

IOTA  Cobb  1913 

7.  Iota  simile,  n.  sp.  ~879 o7«~  ~7<)7s~^~i7I 676  '6 ""  Tne  colorless  layers  of 

the  thick  cuticle  are  traversed  by  ninety  to  one  hundred  plain,  transverse 
striae  of  such  a  nature  as  to  give  a  relatively  coarse  serrate-crenate  appearance 
to  the  contour  of  the  body.  The  annules  of  the  cuticle  are  complete  rings. 
Only  at  rare  intervals  is  there  a  trace  of  anastomosis;  occasionally  it  will 
happen  that  two  semi-annules  on  one  side  of  the  body  are  joined  to  one  on  the 
other.  The  convex-conoid  neck  ends  in  a  somewhat  rounded  head  surmounted 
by  a  flat  lip  region  composed  probably  of  six  very  flat  lips  placed  in  the  slightly 
depressed  front  surface  of  the  first  annule.  The  first  two  or  three  annules  are 
packed  closely  together,  and  the  prevalent  crenate-serrate  appearance  of  the 
contour  begins  probably  with  the  fourth  annule,  possibly  with  the  third.  No 
labial  papillae  have  been  seen.  Nothing  is  known  concerning  the  amphids. 

Spear.  The  spear  is  rather  more  slender  than  in  most  Iotas,  and  tapers 
throughout  the  main  portion  of  the  shaft,  which  constitutes  fully  two-thirds  of 
the  length.  Where  it  reaches  its  maximum  development  this  shaft  has  a  diameter 
about  half  as  great  as  the  width  of  one  of  the  neighboring  annules  of  the  cuticle. 
Behind  the  shaft  the  hilt  of  the  spear  has  a  diameter  only  a  trifle  larger  than  that 
of  the  main  portion  of  the  shaft.  The  hilt  increases  in  diameter  steadily 
posteriorly,  and  finally  expands  suddenly  into  a  large  three-fold  bulb  nearly 
one-fourth  as  wide  as  the  corresponding  portion  of  the  neck.  The  central  canal 
of  the  spear  is  plainly  visible,  and  is  continuous  with  that  of  the  oesophagus. 

Oesophagus  and  Intestine.  The  oesophagus  is  about  as  wide  as  the  base  of 
the  spear,  and  appears  to  present  no  very  definite  median  bulb,  though  there 
is  a  slight  change  near  the  middle  of  the  neck  which  probably  indicates  the 
position  of  some  such  structure.  The  details  of  the  intestine  are  somewhat 
obscure,  but  it  appears  to  begin  as  a  tube  about  half  as  wide  as  the  body,  and  to 
continue  at  this  width  for  some  distance.  The  anus  seems  to  be  located 
between  the  fourth  and  fifth  annules,  counting  from  the  posterior  extremity. 
The  excretory  pore  is  located  near  the  twenty-sixth  annule  counting  from  the 
head  end  where  the  annules  first  become  distinctly  developed;  this  means  prob- 
ably at  about  the  thirtieth  annule  counting  from  the  mouth  itself.  The  tail  is 
conoid  to  the  blunt  terminus,  which  is  destitute  of  a  spinneret. 

Sexual  Organs.  The  depressed  vulva  is  located  at  about  the  seventh  annule 
from  the  caudal  extremity.  The  vagina  leads  inward  and  forward  a  distance 
fully  equal  to  the  corresponding  body  width.  In  front  of  this  is  the  uterus, 
which  appears  to  be  once  and  one-half  to  twice  as  long  as  the  corresponding 
body-diameter.  The  ovary  extends  directly  forward  and  its  blind  end  lies 
some  little  distance  behind  the  base  of  the  neck.  The  eggs  occur  one  at  a  time 
in  the  uterus.  They  are  thin-shelled,  a  little  longer  than  the  corresponding 
body  diameter  and  about  half  as  wide  as  long. 

Habitat:  Aberrant  in  filter  beds,  Washington,  D.  C. ;  roots  of  grape-vine, 
Herman,  Mo.  Synonymous  with  Iota  are  Ogma  Southern  and  Criconema  Hof- 
manner  and  Menzel.  Iota  consists  of  many  species.  I  have  specimens  and  full 
MS.  descriptions  of  a  number  of  new  species  collected  during  the  last  twenty 
years  in  widely  different  parts  of  the  world.  All  are  -f  and  have  the  vulva 
hidden  among  the  annules  near  the  anus;  tiny,  wide  nemas  with  retrorse  annules. 


FOOD    HABITS   OF    MOXHYSTERA 


205 


MONHYSTERA  Bastian  1865 


M.  subfiliformis  n.  sp. 


2./  2. 

This  form,  which  appears  to  be  new,  is  closely 
related  to  Monhystera  filiformis  Bastian,  but  dif- 
fers from  the  descriptions  given  by  various  authors 
in  the  following  respects: — There  are  10  cephalic 
setae  on  subfiliformis  instead  of  six.  The  am- 
phids  are  somewhat  larger  than  given  by  most 
authors  for  filiformis.  In  the  cardiac  region  I 
have  noticed  in  the  single  specimen  of  the  present 
species  so  far  examined,  a  very  definite  pseudo- 
bulb.  There  is  a  definite  renette,  as  shown  in  the 
figure,  with  an  excretory  pore  opposite  the  nerve 
ring.  The  eggs  are  relatively  larger  than  de- 
scribed for  filiformis.  The  anatomical  details  are 
clearly  shown  in  Fig.  7.  This  species  also  shows 
a  certain  amount  of  resemblance  to  Monhystera 
vulgaris,  de  Man,  but  differs  in  having  setae  on 
the  body,  and  in  having  10  cephalic  setae,  and  in 
the  amphids  being  slightly  different  in  position, 
form  and  size.  The  tail  of  vulgaris  also  seems  to 
be  more  slender. 

Habitat:  Sand,  Washington  filter  beds;  j|/^Jf 
usually     uncommon.    Of    the    numerous  ^      . 
species   of  Monhystera  I   have  had  occa-  Un°c™m- 
sion  to    examine    with    respect  to    their 
food   habits,   all  appear  to  be  largely  if 
not  wholly  vegetarian.     The  various  spe- 
cies specialize  to  a  considerable  degree  in 
the  matter  of  food.     For  instance,  many 
marine   species   feed    almost    exclusively 
on  diatoms.     If  the  filterbed  Monhysteras 
are  not  an  exception  to  the  rule,   they 
would  seem  to  be  dependent  on  fungi  and 
bacteria   as  a  source  of  food,  except   in 
open  beds,  where  of  course  they  would 
find  an  abundance  of  green  microphytes. 


CYLINDROLAIMUS  de  Man  1884 

Sexual  Organs.  Cylindrolaimus  typi- 
cally has  but  a  single  outstretched  ovary; 
from  the  observations  of  various  authors 
it  would  appear  that  this  may  extend 
either  forward  or  backward,  usually  for- 
ward. As  there  is  some  doubt  about  the 
shape  of  the  organ  in  the  type  species 
communis,  it  is  desirable  that  specimens 
of  that  species  be  reexamined.  Inasmuch 
as  the  male  of  only  one  of  the  six  true 
species  of  Cylindrolaimus  has  been  seen,  it 
would  seem  that  the  genus  is  typically 


,//„// 


206 


FILTER-BED   NEMAS 


syngonic  or  digonic.  Such  observations  as  I  have  been  able  to  make  upon 
glycerine  specimens  of  obtusus  lead  me  to  conclude  that  this  species  at  least 
is  probably  digonic;  if  it  is  syngonic  we  are  confronted  with  the  phenomenon 
of  the  ovary  first  acting  as  a  testis  and  sending  over  into  the  rudimentary 
posterior  part  spermatocytes,  probably  primary  spermatocytes,  there  to  con- 
tinue their  development. 


9.  Cylindrolaimus  obtusus  Cobb. 


-  58? 
3.5 


Fig.      8      Cyl- 
indrolaimus 


2.6         3.3          3.5        Z.8  ' 

The  moderately  thin  cuticle 
is  traversed  by  five  to  six  hun- 
dred  transverse  striae,  which  do 
not  appear  to  be  further  resolv- 
able. In  glycerine  specimens 
there  are  very  faint  indications 
of  longitudinal  striations,  which 
are  more  pronounced  toward  the 
anterior  extremity;  these  may  be 
due  merely  to  the  attachments  of 
the  somatic  muscles.  There  ap- 
pear to  be  no  very  distinct  lips, 
though  probably  minute  lips  are 
present,  —  so  small  and  so  closely 
amalgamated  as  easily  to  escape 
observation.  Occasionally  six 
excessively  minute  papillae  have 
been  seen  immediately  round  the 
mouth  opening;  though  no  doubt 
always  present,  these  papillae 
usually  escape  observation. 
When  the  lips  are  closed  the 
small  mouth  opening  appears  as 
a  simple  pore  in  the  middle  of 
the  front  of  the  head,  where 
there  is  an  exceedingly  minute 
depression.  Four  submedian, 
somewhat  papilla-like,  widely- 
spreading  cephalic  setae  occur 
on  the  margin  of  the  head  about 
half  way  between  the  anterior 
extremity  and  the  front  of  the 
amphids;  each  of  these  setae  is 
about  one-fourth  as  long  as  the  corresponding  diameter  of  the  head.  The 
well-developed  lateral  fields  are  about  one-third  as  wide  as  the  body.  There 
do  not  appear  to  be  any  distinct  wings. 

Intestine.  Ovary.  The  somewhat  cylindroid  cardia  is  of  relatively  large 
size,  and  is  separated  from  the  oesophagus  by  a  constriction;  it  is  about  two- 
fifths  as  wide  as  the  base  of  the  neck,  and  is  surrounded  by  about  seven  uni- 
cellular organs,  probably  glandular  in  nature.  There  is  a  small  posterior  branch 
of  the  sexual  apparatus,  extending  backward  a  distance  about  equal  to  the  length 
of  the  body  diameter,  serving  either  as  a  testis  or  spermatheca,  apparently  the 
former.  The  ellipsoidal,  thin-shelled,  smooth  eggs  are  five-sixths  as  wide  as 


X675 


PLECTUS    CIRRATUS  207 

the  body,  and  about  two  to  two  and  one-half  times  as  long  as  wide.     They  appear 
in  the  uterus  one  at  a  time  and  seem  to  be  deposited  before  segmentation  begins. 

Habitat:  Sand,  Washington  filter  beds,  early  in  January  1916,  at  the  end 
of  about  five  months'  use.  Not  common.  No  males  seen. 

PLECTUS  Bastian  1865 

10.  Plectus  cirratus,  Bastian.  ~iT?  ?!,4  -  47? — TT  "iV1-  ""  Taking  the  de- 
scriptions and  figures  of  de  Man  as  the  basis  of  his  identification,  Maupas 
made  numerous  and  very  careful  observations  upon  this  species;  he  never 
found  males,  and  concluded  from  this  and  his  other  observations  that  the  species 
is  purely  parthenogenetic.  As  my  own  observations  do  not  agree  with  those  of 
Maupas,  it  is  well  to  consider  carefully  whether  the  species  observed  by  us  are  the 
same.  My  specimens  came  from  the  Potomac  River  near  Washington,  D.  C.,  U.S.A., 
and  in  size  and  proportions  agree  in  all  respects  with  the  figures  and  descriptions 
of  de  Man.  The  anatomy  of  my  specimens  also  appears  to  agree  in  all  essential 
respects  with  that  set  forth  by  de  Man.  There  is  a  little  uncertainty  about  the 
number  of  cephalic  setae  as  reported  by  de  Man;— in  one  instance  he  says  four, 
in  another  six.  Bastian's  original  description,  made  from  specimens  ^  in. 
long,  says  four.  In  the  description  in  which  de  Man  placed  the  number  at  six 
his  corresponding  illustrations  are  possibly  open  to  the  interpretation  that  four 
only  were  present.  The  Potomac  specimens  always  present  four  cephalic  setae. 
The  caudal  setae  of  the  Potomac  specimens  are  not  so  prominent  as  indicated  in 
de  Man's  figures.  My  specimens  present  the  amphids  at  precisely  the  point 
indicated  by  de  Man,  and  of  very  nearly  the  same  size.  De  Man  does  not  give 
a  very  clear  indication  of  the  shape  of  the  amphids,  but  I  see  no  reason  to  consider 
the  two  forms  specifically  or  varietally  different  on  the  basis  of  the  shape  and 
position  of  the  amphids.  There  exists,  therefore,  only  the  uncertainty  with 
regard  to  the  cephalic  setae,  and  this  may  not  in  fact  be  a  discrepancy.  Maupas 
shows  five  eggs  in  each  uterus.  It  is  uncommon  for  the  Potomac  specimens  to 
present  as  many  eggs  as  this  in  the  uterus;  the  common  number  is  one  or  two,  but 
it  may  rise  to  four.  De  Man  describes  the  egg-shells  as  smooth ;  Maupas,  however, 
says  they  are  covered  with  minute  points.  The  Potomac  specimens  agree 
with  Maupas'  description.  I  am  therefore  most  strongly  inclined  to  believe  that 
the  forms  examined  by  Maupas  and  myself  are  the  same. 

Maupas,  in  his  description  of  the  development  of  the  egg,  notes  the  following 
points:  In  one  case  only  among  a  large  number  of  developing  ova  examined 
did  he  see  more  than  a  single  nuclear  figure.  He  considers  this  an  important 
point  in  his  demonstration  of  the  parthenogenetic  character  of  the  develop- 
ment. He  observed  that  when  the  egg  entered  the  uterus  it  lost  its  definite 
nucleus  for  an  hour  or  more,  and  concluded  that  during  this  period  the  polar 
bodies  were  formed,  although,  as  he  says,  he  never  saw  any  polar  bodies,  but 
observed  amoeboid  movements  in  the  ovum  during  the  absence  of  the  nucleus. 
Maupas  says  that  it  was  with  much  difficulty  that  he  convinced  himself  that  no 
spermatozoa  were  present  in  the  sexual  organs  of  this  Plectus,  but  that  in  spite 
of  careful  examination  he  never  succeeded  in  seeing  any.  Nor  did  he  see  the 
slightest  trace  of  spermatozoa  on  removing  the  sexual  organs  and  treating  them 
with  acetic  acid.  He  therefore  took  the  species  to  be  parthenogenetic.  Never- 
theless, he  noted  occasionally  in  the  distal  end  of  the  uterus  refractive  bodies 
of  exceedingly  small  size.  As  will  appear  later,  it  is  not  at  all  improbable  that 
these  minute  bodies  were  really  spermatozoa  which  he  failed  to  recognize  as  such. 


208 


FILTER-BED   NEMAS 


xtqt 


Chromosomes.    Zygosis.     Using  the  best  modern  instruments,  under  favorable 
conditions,  it  is  possible  to  see  the  spermatozoa  of  Plectus  cirratus  in  living 
Fig.  9.    Plectus     specimens  of  the  right  age  and 
cirratus,       which 
like  many  other 
species  of  Plectus 
is    syngonic.    An 
egg  is  seen  in  2nd 
maturation    divi- 
sion, chrsm  (6  +  6). 
SHiut 

da; 


condition.     The  most   suitable 
age  for  such  observations  ap- 
pears to  be   that  at  Avhich  the 
spermatozoa  are  about  to  enter 
the  uterus,— the  stage  when  the 
sexual  organs  appear  quite  sim- 
ple, and  the  uterus  has  the  form 
of  a  rather  narrow  empty  tube. 
On  searching  for  spermatozoa  or 
spermatocytes  near  the  large  or 
proximal  end   of   the   ovary   it 
will  usually  be  possible  to  find 
them  without  examining  many 
specimens.    It  may  be  necessary 
to  view  the  specimens  at  a  par- 
ticular angle,  and  it  may  require 
a  number  of  trials  to  secure  a 
favorable    specimen.     Fixation 
with   hot    corrosive    sublimate, 
followed   by    an    acid    carmine 
stain  and  long  destaining,   de- 
monstrates the  presence  of  sper- 
matozoa  at   almost    any    stage 
after  they  are  formed,  up  to  the 
time    when    all    have 
been    utilized.     Using 
such  material,  I  have 
been  able  to  trace  the 
spermatozoon  into  the 
egg,  and  show  that  the 
spermatozoon  displays 
about  six  chromosomes 
at  a  time  when  its  two 
centrosomes  appear  on 
the  side  next  the  egg- 
nucleus,    which  under 
its    influence    divides, 
and  forms  two  distinct 
groups  of  chromosomes 
consisting  of  six  each. 
Indefinite    bodies    are 
formed  in  the  vicinity 
of  the  egg  nucleus  which 
appear  to  have  the  sig- 
nificance of  polar  bodies;  see  Fig.  9,  where  one  is  showrn  faintty  at  corp  plr  (/.!. 
Syngonic.    My  observations  leave  me  without  the  slightest  doubt  that  this 
Plectus  is  syngonic,  and  that  the  spermatozoa  are  functional.     Rather  casual 
observations  I  have  made  on  other  species  of  Plectus  prove  that  syngonism  is 


HERMAPHRODITISM    IN    NEMAS  209 

common  in  this  genus,  and  that  similar  spermatozoa  are  present  in  a  number  of 
other  species,  but  thus  far  I  have  no  proof  that  in  these  other  species  the  sperma- 
tozoa are  functional.  These  results  lend  additional  emphasis  to  my  suggestion, 
made  in  previous  papers,  that  parthenogenetic  species  in  general  be  reexamined 
with  a  view  to  ascertaining  whether  some  of  them  do  not  present  spermatozoa 
of  minute  size.  As  in  the  present  case,  species  hitherto  regarded  as  partheno- 
genetic may  prove  to  be  syngonic.  Probably  thousands  of  nemas  are  syngonic. 

Hermaphroditism  in  Nemas.  Dr.  E.  Maupas  in  1900  summarized  to  that  date 
a  list  of  34  hermaphroditic  species  belonging  to  12  different  genera,  as  follows:— 
Rhabditis,  Diplogasier,  Cephalobus,  Plectus,  Allantonema,  Bradynema,  Micro- 
laimus,  Angiostomum,  Strongyloides,  Dorylaimus,  Aphelenchus,  and  Alaimus:— 
four  of  them  parasitic,  the  remainder  free-living.  These  34  species  represent 
varying  degrees  of  hermaphroditism,— from  species  with  two  sexes,  both  func- 
tional, but  presenting  also  females  capable  of  developing  their  own  spermatozoa, 
to  those  in  which  only  female  forms  are  known,  but  in  the  gonads  of  which  first 
spermatozoa  then  ova  are  produced,  the  spermatozoa  serving  to  fertilize  ova 
from  the  same  gonad.  Of  these  34  species,  over  half  belong  to  Rhabditis. 

Syngonic  Forms.*  I  have  recently  taken  occasion  to  look  somewhat  carefully 
into  the  embryology  of  a  number  of  species,  all  of  which  prove  to  be  syngones 
or  digones.  These  are  the  filter-bed  species  Mononchus  longicaudatus  Cobb, 
Ironus  ignavus  Bastian,  Ironus  longicaudatus  de  Man,  Plectus  cirralus  Bastian 
and  Tripyla  monohystera  de  Man,  all  species  that  have  been  repeatedly  investi- 
gated by  different  observers  in  various  parts  of  the  world.  To  three  of  them 
males  are  unknown;  in  the  case  of  the  fourth,  Ironus  ignavus,  the  males  have  been 
seen  but  rarely.  In  addition  I  have  examined  an  interesting  new  genus,  Monon- 
chulus,  also  hermaphroditic.  In  the  course  of  my  investigations  extensive 
series  of  individuals  have  been  examined,  in  nearly  every  case  several  hundred, 
all  of  which  proved  to  be  syngonic  females  (digonic  in  Mononchulus).  As  in 
most  of  the  other  hermaphroditic  nemas,  the  spermatozoa  are  produced  in  the 
young  gonad  and  are  early  sent  forward,' — often  to  a  special  receptacle,— where 
they  await  the  arrival  of  the  ova. 

Potency  of  Syngonic  Sperm.  In  the  light  of  recent  researches  on  the  fertili- 
zation of  the  ovum  several  interesting  questions  again  arise  in  connection  with 
the  origin,  development  and  function  of  these  spermatozoa  produced  by  gones 
which  simultaneously  or  subsequently  produce  ova.  Are  these  spermatozoa 
functional?  That  is  to  say,  do  they  fertilize  the  ova  in  the  "regular"  manner? 
Do  the  syngonic  spermatozoa  enter  the  egg  and  behave  in  every  respect  like  those 
produced  in  a  separate  male  organism,  or  do  they  behave  in  some  other  way? 
To  answer  these  questions,  among  other  things  the  history  of  the  chromosomes 
throughout  the  ripening  of  both  sperm  and  ova  should  be  accurately  known, 
and  then  compared  with  the  corresponding  facts  in  typical  amphigonic  species. 

]'(in.ishing  Series  of  Spermatozoa.  Mainly,  previous  researches  have  given 
us  the  records  of  species  in  which  the  spermatozoa  produced  by  syngonic  females 
were  of  the  same  size  and  form  as  those  produced  by  the  few  males  that  a  so 
occurred,  that  is  to  say  relatively  of  very  considerable  size.  In  some  species  the 
males  of  which  are  unknown,  the  recorded  spermatozoa,  found  in  the  female, 
are  relatively  small  and  difficult  ^o  observe.  My  own  researches  have  led  me 
to  cases  more  and  more  difficult  to  decipher,  owing  to  the  smaller  and  smaller 
size  of  the  spermatozoa  discovered,  and  ended  in  cases  in  which  I  was  left  com- 
pletely in  doubt  as  to  the  existence  of  spermatozoa;  I  could  find  none,  but  the 
nature  of  my  experience  did  not  permit  me  to  conclude  that  therefore  none 

•For  the  terminology  used  in  the  following  discussion,  see  pp.  126,  127. 


210  FILTER-BED  NEMAS 

existed.  Sometimes  the  spermatozoa  are  so  small,  and  so  difficult  to  observe, 
even  under  the  best  of  conditions  and  with  the  best  instruments  used  by  ex- 
perienced observers,  as  to  lead  me  to  begin  to  question  the  adequacy  of  the  evi- 
dence upon  which  we  base  our  belief  in  some  cases  of  alleged  parthenogenesis. 
May  it  not  be  that  sperm  cells,  small  and  difficult  to  observe,  have  escaped  notice? 

Potency.  As  to  the  efficacy  of  these  small  spermatozoa,  in  all  the  cases  I 
have  observed  there  seems  to  be  a  fair  volume  of  evidence  that  the  eggs  are  fer- 
tilized by  the  entrance  of  a  body  so  closely  resembling  one  of  these  small  sperma- 
tozoa as  to  leave  either  no  or  little  doubt  that,  so  far,  the  phenomena  are  identical 
with  those  of  bisexual  fertilization.  Spindles  and  polar  bodies  are  formed,  though 
sometimes  the  evidence  is  not  complete.  Unfortunately,  in  most  of  the  cases  I 
have  observed,  the  chromosomes  are  so  small  and  crowded  as  thus  far  to  preclude 
exact  counting;  I  am  therefore  unable  to  say,  on  the  basis  of  fully  satisfactory 
observations,  that  fertilization  always  takes  place  in  the  same  manner  as  in  the 
case  of  females  fertilized  by  copulation  with  males.  I  can  only  say  that  my 
evidence,  as  far  as  it  goes,  points  that  way  in  a  considerable  number  of  species. 

In  view  of  the  present  developments  this  would  seem  to  be  a  matter  in  which 
it  is  well  to  keep  clearly  in  mind  that  no  amount  of  not  seeing  a  thing  proves  that 
it  does  not  exist.  It  is  no  longer  the  case,  as  it  formerly  was,  that  non-existence 
of  males  may  be  regarded  as  proof  of  parthenogenesis.  We  must  prove  that 
there  are  no  functional  spermatozoa  produced  by  the  females  themselves.  Has 
this  always  been  done?  I  think  the  answer  must  be  "No,"  or  "Not  satisfactorily." 

Road  to  Parthenogenesis?  With  Maupas  one  may  suspect  syngonic  nemas  to 
be  on  the  road  to  parthenogenesis.  This  suspicion  may  be  justified  on  the 
ground  that  we  find  species  producing  two  groups  of  sexual  cells,  one  male,  the 
other  female,  variously  arranged  with  respect  to  each  other  all  the  way  from 
amphigony  to  the  most  intimate  syngony,  a  series  at  once  suggesting  the  hypoth- 
esis that  bisexual  nemas  may  be  evolving  along  this  road  to  parthenogenesis. 
What  would  be  the  ulterior  (post-parthenogenetic)  steps  in  such  an  evolution? 

Consider  for  a  moment  the  origin  of  the  gonic  cells  in  a  syngonic  nema:  At 
some  time  in  the  growth  of  its  gone  all  the  future  ova  and  spermatozoa  exist 
in  the  form  of  a  single  or  primary  gonic  cell,  destined  to  give  rise  both  to  sper- 
matocytes  and  oocy  tes.  The  spermatocy  tes  usually  take  the  lead  in  development 
and  give  rise  to  spermatozoa  that  are  lodged  in  the  uterus.  In  some  cases  almost 
simultaneously,  in  others  only  a  few  hours  later,  the  oocytes  begin  to  develop, 
and  give  rise  to  ova,  which  in  turn  pass  onward  to  be  fertilized  by  the  sperma- 
tozoa already  produced  by  the  same  gone.  Admitting  the  crudeness  of  the 
questions, — Is  not  this  conceivably  a  wasteful  method?  Under  the  circum- 
stances might  it  not  be  more  "economical"  to  produce  only  one  kind  of  cell, 
each  such  cell  to  contain  both  male  and  female  elements?  Why  separate  these 
complements  only  to  bring  them  together  again  so  soon?  These  queries  are  of 
course  merely  suggestive,  and  are  not  meant  to  outline  the  whole  subject. 

The  original  gonic  cell  of  a  syngone  gives  rise  to  both  spermatozoa  and  ova; 
hence  there  exist  in  it,  among  other  things,  both  male  and  female  potentialities: 
these  must  have  some  physical  embodiment, — of  course  not  necessarily  dis- 
cernable.  Should  these  potentialities,  male  and  female,*  be  separately  embodied 
in  the  original  gonic  cell  in  numbers  suitable*  each  to  each,  why  might  they  not 
there  and  then,  in  ways  harmonious  with  those  familiar  in  amphigony,  segre- 
gate their  parts  and  regroup  them,  and  afterward  develop  in  the  form  of  some 
fractional  number  of  syncysts?  Is  this  anything  more  than  following  to  what 
would  appear  to  be  a  logical  conclusion,  the  tendencies  apparently  existing  in 

*  "Potentialities,  male  and  female",  being,  of  course,  merely  members  of  a  series  of  potentialities 
subject  to  heredity. 


CKYPTOGENESIS,  PARTHENOGENESIS  211 

syngonic  nemas?  Proof  of  the  existence  of  this  form  of  genesis,  for  which  I  have 
suggested  the  name  cryptogenesis.*  will  place  parthenogenesis  in  a  new  light. 
Evidence  for  or  against  cryptogenesis  should  be  sought  in  the  structure  and  be- 
havior of  the  "oocytes"  and  "ova"  of  syncystic  forms.  From  some  forms  of  syn- 
gony  it  would  appear  to  be  hardly  more  than  a  few  steps  along  this  road  to  par- 
thenogenesis, itself  perhaps,  as  it  were,  a  waystation  en  route  to  cryptogenesis. 
There  have  been  three  main  theories  of  natural  parthenogenesis: 

1.  Owen's,  that  not  all  the  germinal  matter  is  necessary  for  the  production 
of  the  new  organism,  and  that  after  the  new  organism  has  matured,  a  left  over  por- 
tion of  the  germinal  matter  within  it  proceeds  to  develop  new  organisms. 

2.  Huxley's,  that  the  parthenogenetic  "egg"  is  not  in  reality  an  ovum,  and 
that  its  development  is  comparable  to  the  growth  of  an  organism  from  a  bud. 

3.  Hertwig's,  that  parthenogenesis  is  a  degenerate  fertilization. 
Parthenogenesis  as  commonly  understood  may  be  said  to  be  of  three  kinds: 

a,  The  resultant  generation  is  all  female  (homocystic).  b,  The  resultant  genera- 
tion is  all  male  (homocystic).  c,  The  resultant  generation  is  heterocystic.  Fur- 
thermore it  may  be  divided  into  three  cases: 

1.  The  parthenogenetic  generation  alternates  strictly  with  a  bisexual  one. 

2.  Several  parthenogenetic  generations  occur  between  the  bisexual  ones. 

3.  Pure  syncysty;  i.e.,  no  reproduction  other  than  parthenogenesis  is  known. 
A  common  supposition  is  that  the  parthenogenetic  gamete  is  an  ovum  or 

macrogamete  pure  and  simple.  It  seems  more  difficult  to  explain  the  three  kinds 
of  parthenogenesis  on  the  supposition  that  the  gamete  of  the  parthenogenetic 
organism  is  essentially  or  only  an  ovum  or  macrogamete,  than  on  the  supposition 
that  this  gamete  is  syncystic ;  for  this  latter  supposition  makes  it  easy  to  imagine 
the  different  results  of  natural  parthenogenesis  to  arise  by  processes  similar  to 
those  already  familiar  in  heterocysty. 

Cryptogenetically  considered  even  parthenogenesis  may  be  conceived  of  as  a 
concealed,  (often  perhaps  unseeable  or  at  least  hitherto  unseen)  but  more  or 
less  "normal"  genesis. 

A  strict  construction  of  the  phase  of  cryptogenesis  discussed  rests  on  the 
supposition  that  what  we  have  been  calling  parthenogenesis  is  one  phenomenon, 
and  not  a  collection  of  more  or  less  related  phenomena.  My  own  present  view 
is  that  this  latter  clause  probably  comes  nearer  the  truth,  and  that  partheno- 
genesis as  we  have  broadly  understood  it  may  possibly  cover  cases  in  accord 
with  most  of  the  theories  that  have  been  proposed.** 

Cryptogenesis  may  not  exhibit  all  the  phases  investigation  has  disclosed  in 
heterocysty;  the  suggestion  is  rather  not  only  that  all  the  results  accomplished  or 
supposed  to  be  accomplished  in  natural  parthenogenesis  may  be  explicable  along 
the  lines  of  ordinary  fertilization,  but  that  parthenogenesis,  and  cryptogenesis 
if  it  exist,  is  not  so  much  a  distinct  method  of  generation,  or  even  a  degenerate 
fertilization,  as  an  evolved  amphigony. 

There  is  a  certain  amount  of  evidence  often  interpreted  as  showing  that 
fertilization  cannot  be  superimposed  on  parthenogenesis,— e.g.,  parthenogenetic 
eggs  may  "resist"  sperm  of  the  same  species.  In  normal  fertilization  once  an  egg 
entered  by  a  spermatozoon  it  thereafter  "resists"  the  entrance  of  other  sper- 
matozoa. If  what  we  have  been  calling  parthenogenesis  is,  in  any  given  case, 
in  reality  cryptogenesis,  then  the  parthenogenetic  eggs  may  be  regarded  as 

*  This  conception  differs  from  earlier  ones  in  its  space-and  time-limits,  (time,  antecedent;  space 
the  confines  of  ancestral  gonic  colls),  and  in  that  its  methods  and  mechanism  are  extended  to  possibly 
include  all  the  phases  known  for,  or  postulated  of,  the  forms  of  genesis  from  wnich  it  is  supposed  to  ho 
evolved. 

**  Here  we  seem  unconsciously  dominated  by  our  terminology,  some  of  which  is  outgrown  and,  as  ap- 
plied, even  misleading.  The  facts  and  ideas  need  critical  analysis,  as  well  as  the  benefit  of  an  adequate 
terminology,  as  Sir  E.  Ray  Lankester  has  just  indicated  in  the  August  number  of  "Nature"  (1917). 


212 


FIETER-BED   NEMAS 


already  having  the  substances  or  factors  imparted  by  the  spermatozoon,— 
or  their  equivalent, — and  we  might  therefore  expect  such  eggs  to  be,  as  they  are, 
"resistant"  to  sperm.  Whether  or  not  this  suggestion  has  a  basis  of  fact,  the 
theory  of  cryptogenesis  harmonizes  with  what  is  known  about  the  incompat- 
ibility of  parthenogenesis  and  fertilization.  Of  course  ova  may  be  too  young 
to  be  fertilized,  or  too  old  to  be  fertilized,  and  their  parts  may  be  so  acted  upon 
by  a  variety  of  forces  as  to  bring  them  into  a  more  responsive  or  less  respon- 
sive condition;  needless  to  say,  these  various  facts  must  also  be  taken  carefully 
into  account  in  any  such  speculation  as  the  foregoing. 

Abbreviations  Used  in  the  Illustrations 


Amp,  ampulla 
amp    sal    dct,     ampulla  of 

~fng,  ingested  material 
-1-    ing  nematod,  ingested  noma- 

ov  dct,  oviduct 
ov  frt,  fertilized  egg 

salivary  duct 

tode 

ov  im,  immature  egg 

amp  subm,  submedian  ampulla 

int,  intestine 

ovr  rud,  rudimentary  ovary 

amp  vnt,  ventral  ampulla 

int  cryst,  intestinal  crystal 

ov  ut,  uterine  egg 

ompA,  amphid 

int  lum,  intestinal  lumen 

an,  anus 
an  gl,  anal  gland 
apic,  apiculum 

Tnc.  junction 

ID  spn,  mouth  of  spinneret 
-*-        par,  parasite 
ph,  pharynx 

ar  dnt,  rasp 
ar  la!,  lateral  field 
ar  vnt,  ventral  field 

Lam  Ib,  labial  lamina 
Ib,  lips 
H>  ppl,  labial  papilla 

ph  str,  pharyngeal  striae 
por  or  p,  pore 
por  gl  oe,  pore  of  oeso;>hasoal 
gland 

Bos  ph,  base  of  pharynx 
W6  crd,  cardiac  bulb 

lum  int,  intestinal  lumen 
1  urn  oe,  oesophageal  lumen 
lum  som,  body  cavity 

por  sal,  mouth  of  the  salivary 
gland 
por  sal  dsl,  mouth  of  dorsal  sal- 

Cav  som,  body  cavity 
chrsm,  chromosome 
cl  ar  lot,  cell  of  the  lateral  field 
rl  crd.  cell  of  cardia 
cl  int,  intestinal  cell 
cl  lot,  lateral  coll 
cl  msc,  muscle  cell 

TVTrt,  mitosis  figure 
-LVJ-    msc  an,  anal  muscle 
msc  oe,  oesophagus  muscle 
msc  ph,  pharyngeal  muscle 
msc  som,  body  muscle 
msc  valv,  valve  muscle 
msc  tlv.  vulva  muscle 

ppl,  papilla 
ppl  cdl,  caudal  papilla 
ppl  cph,  cephalic  papilla 
ppl  intr,  interior  panilla 
ppl  lat,  lateral  paoilla 
ppl  Ib,  labial  papilla 
ppl  Ib  extr,  exterior  labia!   pa- 

cl nrv.  nerve  cell 

mur  int,  intestinal  wall 

pilla 

cl  nrv  an,  anal  nerve-cell 
cl  nrv  cdl,  caudal  nerve-cell 
cl  nn  crd,  cardiac  nerve-cell 

mur  ph,  pharyngeal  wall 
mur  ut,  wall  of  uterus 

ppl  subm.  submedian  papilla 
ppl  subm  sec,  secondary  subme- 

cl  nrv  dsl,  dorsal  nerve-cell 
d  nrv  lot,  lateral  nerve-cell 
cl  nrv  subm.,  submedian  nerve- 
cell 
cl  nrv  vnt,  ventral  nerve-cell 

"M"ci,  nucleus 
A1     ncl  ar  lot,  nucleus  of  lat- 
eral field 
ncl  cl  int,  nucleus  of  intestinal 
cell 

ppl  trm,  terminal  papilla 

"D  cpt  sem,  seminal  receptacle 
**    ret,  rectum 
reg  vnt,  ventral  field 

cntr,  centrosome 
corp  pol  I,  1st  polar  body 
cpA  ppZ,  cephalic  papilla 
cph  set,  cephalic  seta 

nd  cl  nrv,  nucleus  of  nerve  cell 
ncl  gl  cdl,  nucleus  of  a  caudal 
gland 
ncl  lot,  lateral  nucleus 

ren,  renette 
rot,  rotifer 
rot  ing,  ingested  rotifer 

crd,  cardia 
cst  ph,  pharyngeal  rib 

ncl  msc,  nucleus  of  muscle 
ncl  nrv,  nerve  nucleus 

CJa?,  salivary  gland 
0    sal  dct,  salivary  gland  duct 

cut,  cuticle 

nd  oe,  oesophageal  nucleus 
ncl  ov,  nucleus  of  egg 

sal  dsl,  dorsal  salivary  gland 
sal  gl  dsl,  dorsal  salivary  gland 

TV',  duct 

ncl  ov  im,  nucleus  of  ovum 

sal  subm,    submedian    salivary 

*->    dct  gl  cdl,  duct  of  caudal 

ncl  ren,  renette  nucleus 

gland 

gland 

ncl  ut,  nucleus  of  an  uterine  cell 

sec,  secretion 

dct  ren,  renette  duct 

ncl  vlv.  nerve  nucleus  of  valve 

sec  cdl,  caudal  secretion 

dct  sal  dsl,  dorsal  salivary  duct 
div  red,  reduction  division 

nd  vnt,  nucleus  of  the  ventral 
field 

set,  seta 
set  cph,  cephalic  seta 

dnt.  denticles 

nr,  nerve 

set  sub-cph,  subcephalic  seta 

nrv,  nerve 

sp,  spiculum 

Ex  p,  excretory  pore 

nrv  af,  afferent  nerve 

spm,  spermatozoa 

nrv  r,  nerve  ring 

spn,  spinneret 

nrv  vnt,  ventral  nerve 

spndl,  spindle 

~C*lx  ov,  flexure  of  ovary 
*      flx  ovr  post,  flexure  of  pos- 
terior ovary 

r\e,  oesophagus 
J    oes  lum,   oesphageal  lumen 

spthc,  sperm  atheca 
str  mur  ph,  striae  of  pharyngeal 
wall 

ont  onchus 

subcut,  subcuticle 

n.1,  gland 

on  dsl,  dorsal  tooth 

siit  Ib.  labial  suture 

^     gl  an,  ana!  gland 

on  rtr  dsl,  retrorse  dorsal  onchus 

gl  cdl,  caudal  gland 

on  rtr  subm,  retrorse  submedian 

Trm,  terminus 

gl  cdl  subm,  submediau  caudal 

tooth 

trm  ov,  terminus  of  ovary 

gland 

on  submd  xt,  right  submedian 

trm  ovr,  blind  end  of  ovary 

gl  oe,  oesophageal  gland 

tooth 

gl  sal,  salivary  gland 
gng,  ganglion 

on  subm  snst,   left  submedian 
tooth 

TTf,  uterus 

grn,  granule 

oocyt,  oocyte 

grn  int,  intestinal  granule 

orgf,  organ  of  unknown  signifi- 

\Tag, vagina 

grn   int   maj,    larger   intestinal 

cance 

•      vag  msc,  vaginal  muscle 

granule 

org  elast,  elastic  organ 

valv,  valve 

grn  int  min,  smaller  intestinal 

org  int,  intestinal  organ 

vlv,  vulva,  valve 

granule 

ov,  ovum 

tstbl  vag,  vestibule  of  vagina 

THE  ORDERS  AND  CLASSES  OF  NEMAS*  , 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY,  VIII 
BY  N.  A.  COBB 

Our  first  adequate  conception  of  the  nema  phylum  will  come  from 
a  study  of  the  free-living  forms,  for  in  parasitic  nemas  it  frequently 
happens  that  the  structure  of  important  organs,  especially  those  of  the 
mouth  and  alimentary  canal,  is  greatly  simplified  through  degenera- 
tion. This  degeneration  proves  to  be  relatively  as  marked  among  the 
parasitic  nemas  as  it  is  among  parasitic  species  in  other  phyla  con- 
taining both  free-living  and  parasitic  forms,  so  that  from  the  standpoint 
of  comparative  morphology,  they  are  often  very  highly  perplexing. 
On  the  other  hand,  it  is  already  possible,  through  comparative  study 
of  the  known  free-living  genera,  to  begin  formulating  some  of  the  prin- 
cipal features  of  the  orders  and  classes  of  nemas  and  to  do  it  with  suffi- 
cient truth  and  clarity  to  make  the  results  useful  to  investigators, 
teachers  and  students. 

The  following  table  outlines  a  classification  of  the  phylum,  based 
on  a  study  of  several  hundred  genera.  It  is  a  comprehensive  classi- 
fication I  have  long  employed,  that  has  proved  useful  in  many  ways. 
It  sets  forth  relationships  based  on  and  correlated  with  the  mouth- 
parts.  In  most  animal  phyla  where  there  is  a  distinct  mouth,  oesoph- 
agus and  stomach,  experience  has  amply  proved  the  utility  of  these 
portions  of  the  anatomy  as  a  guide  to  phylogenetic  relationships. 
While  some  parts  of  the  following  scheme  appear  to  outline  clearly  and 
permanently  certain  fundamental  truths,  other  parts  undoubtedly  will 
have  to  be  expanded  or  altered,f  since  our  knowledge  of  details  is  still 
inadequate  to  a  clear  view  of  all  the  larger  relationships. 

In  the  table,  the  order  columns  are  staggered,  in  an  attempt  to 
indicate  relative  importance, — the  farther  to  the  left  the  words,  the 
more  comprehensive  or  significant  is  the  meaning  to  be  attached  to 
the  corresponding  order  name. 

*  Waverly  Press,  July  19,  1919. 

t  Perhaps  it  may  not  be  going  too  far  to  suggest  that,  in  any  such  expansion  and  alteration,  the  aim 
be,  among  other  things,  to  make  the  terminology  of  the  phylum  both  euphonious  and  characteristic. 
Too  few  appear  to  realize  how  important  it  is  that  such  a  terminology  be  (1)  As  descriptive  and  as  nearly 
self-explanatory  as  possible.  (2)  Few,  short  and  consistent  in  its  roots.  (3)  Simple  and  brief  in  its 
terms.  (4)  Characteristic  and  euphonious.  (5)  Such  as  lends  itself  readily  to  modern  inflections  and 
derivations. 

213 


214 


OEDERS   AND    CLASSES   OF   NEMAS 


Phylum  NE MATES 
(Nematoidea  sensu  restricto) 


Subphylum  ALAIMIA* 
Class  Alaimia 
Subclass  Manitinia 

1.  Order 

Subclass  Kinetinia 

2.  Order 

Subphylum  LAIMIA 

Class  Anonchia 
Subclass  Anodontia 

3.  Order 

4.  Order 

5.  Order. . . . 
Subclass  Odontia 

6.  Order 

7.  Order 

Class  Onchia 

Subclass  Homonchia 

8.  Order 

9.  Order 

10,  Order 

11.  Order 

Subclass  Heteronchia 

19.        Order 

13.         Order... 


Anglicised 

Litini  a  Litinian  forms ;  the        Litinia 

Bolbinia  Bolbinian        forms;  the    Bolbinia 


Cytolaimia  Cytolaimian  forms;  the  Cytolaims 
Isolaimia  Isolaimian  forms;  the  Isolaims 
Polylaimia  Polylaimian  forms ;  the  Polylaims 

. .  Apodonlia  Apodontian    forms;  the    Apodonts 

. .  Synodontia  Synodontian  forms ;  the  Synodonts 


Synonchia  Synonchian     forms;  the     Synonchs 

Mesonchia  Mesonchian    forms;  the    Mesonchs 

Aponchia  Aponchian      forms;  the      Aponchs 

Triplonchia  Triplonchian  forms;  the  Triplonchs 

Axonchia  Axonchian      forms;  the      Axonchs 

Anaxonchia  Anaxonchian  forms;  the  Anaxonchs 


*The  names  are  the  plurals  of  latinised  Greek  diminutives  of  the  words,  'to, 
\aifji6o-,  'byx°<r>  with  descriptive  prefixes. 

ALAIMIA 

Nemas  without  distinct  pharynx 

Nemas  devoid  of  pharynx  may  be  conceived  to  be  so  either  because 
they  have  never  developed  a  pharynx  or  have  evolved  ("deteriorated") 
from  forms  having  a  pharynx.  In  the  latter  case,  the  group  ALAIMIA 
may  contain  obscured  equivalents  of  the  subdivisions  of  the  LAIMIA, 
the  nemas  with  pharynx.  It  may  therefore  be  possible  to  subdivide 
the  ALAIMIA  more  fully  after  these  forms,  many  of  which  are  para- 
sitic, have  been  further  considered  in  their  broad  relationships.  In 
this  article  only  two  subdivisions  are  suggested,  of  more  or  less  super- 
ordinal  rank,  the  Litinia,  having  a  simple  oesophagus  without  bulb  or 
swelling,  and  the  Bolbinia,  having  an  oesophagus  with  a  posterior  or 
median  swelling,  or  both. 


ORDERS   AND    CLASSES   OF  NEMAS  215 

LAIMIA 

Nemas  having  a  more  or  less  distinct  pharynx 

A  distinction  is  here  made  among  the  mouth-parts  of  nemas,  based 
on  their  origin,  location  and  method  of  use.  Sometimes  these  organs 
are  labial,  and  sometimes  they  arise  from  elements  deeper  in  the  pharynx 
and  more  closely  associated  with  the  oesophagus  proper.  When  aris- 
ing by  modification  of  the  labial  region  they  are  here  termed  odontia, — 
singular  odontium.  The  odontia  are  usually  of  smaller  size  than  the 
second  class  of  mouth-parts  that  arise  from  elements  farther  back  and 
more  closely  associated  with  the  oesophagus  proper,  and  called  onchs 
or  onchia, — singular  onchium.  The  odontia  are  seldom  less  than 
three  in  number,  and  may  constitute  a  labial  circlet  of  a  dozen  or  more 
elements.  The  onchia  are  almost  never  more  than  three  in  number, 
and  even  then  often  only  one  of  them  is  well  developed. 

According  as  they  are  characterized  by  the  absence  or  presence  of 
onchia,  LAIMIA  may  be  divided  into  two  classes,  the  Anonchia  and 
the  Onchia.  The  Anonchia  may  in  turn  be  divided  into  the  subclasses 
Anodontia  and  Odontia,  according  as  they  lack  or  possess  odontia. 
There  are  three  anodontian  orders,  Cytolaimia,  Isolaimia  and  Poly- 
laimia;  and  two  odontian  orders,  Apodontia  and  Synodontia.  Of  these 
five  orders,  the  first  three  are  characterized  by  the  pharynx  being 
wholly  unarmed,  the  pharynx  of  the  cytolaims  being  a  plain  conoid, 
subspheroidal,  or  somewhat  irregular  cavity,  the  pharynx  of  the  isolaims 
being  mainly  cylindroid  or  prismoid,  i.e.,  parallel-sided,  and  the  pharynx 
of  the  polylaims  being  more  complex  and  composed  of  two  or  three 
successive  chambers  more  or  less  distinctly  separated  from  each  other; 
while  the  latter  two  orders  have  a  pharynx  armed  with  odontia,  the 
odontia  of  the  Apodontia  having  an  outward  stroke,  while  those  of  the 
Synodontia  have  an  inward  stroke. 

The  second  class  of  the  LAIMIA,  the  Onchia,  is  characterized  by  a 
pharynx  armed  with  onchia  or  with  a  spear  composed  of  amalgamated 
onchia,  and  is  divided  into  two  subclasses,  the  Homonchia  and  the 
Heteronchia,  differentiated  from  each  other  by  the  fact  that  in  the 
homonchs  the  onchia  are  similar  to  each  other  and  symmetrically 
arranged  and  nearly  always  three  in  number,  while  the  heteronchs  are 
characterized  by  asymmetrical  onchia,  the  number  of  which  may  be 
reduced  to  one.  There  are  four  orders  of  homonchs  and  two  of  heter- 
onchs. The  four  homonchian  orders  are  the  Synonchia,  in  which  the 
onchia,  nearly  always  three  in  number  and  of  equal  size,  have  an  in- 
ward stroke;  the  Mesonchia,  composed  of  forms  intermediate  between 


216  ORDERS   AND    CLASSES    OF  NEMAS 

the  aponchs  and  the  synonchs,  and  having  three  usually  equal  onchia, 
movable  in  a  direction  parallel  to  the  body  axis;  the  Aponchia,  in  which 
the  onchia,  separate  and  nearly  always  three  or  six  in  number,  have  an 
outward  stroke;  and  the  Triplonchia,  having  a  spear  composed  of  three 
more  or  less  equal,  slender  onchial  elements  which  have  become  amal- 
gamated. The  heteronchian  orders  are,  Axonchia,  having  a  single 
axial  onchium  or  spear,  and  the  Anaxonchia,  in  which  the  main  onchium 
is  not  axial  and  may  or  may  not  be  accompanied  by  one  or  two  others, 
usually  of  smaller  size. 

Onchia  and  odontia  seem  more  or  less  mutually  exclusive,  but  the 
presence  of  one  does  not  necessarily  exclude  the  presence  of  the  other. 
When  both  are  present,  experience  appears  to  indicate  clearly  that  the 
onchia  are  the  more  advantageously  used  as  a  guide  to  broad  relation- 
ships. 

In  a  later  publication  the  proposed  orders  will  be  further  denned  by 
describing  new  type  genera.  In  the  meantime,  the  following  table 
gives  a  tentative  assignment  of  a  few  known  genera,  for  explanatory 
purposes  only.  Reference  to  families  composing  the  orders  is  omitted, 
because  it  appears  to  me  after  studying  a  very  large  number  of  unde- 
scribed  species  in  addition  to  those  described,  that  a  number  of  the 
families  that  have  from  tune  to  time  been  proposed  may  have  to  be 
recast. 

Order  Genus  Order    .  ,  Genus 

LITINIA Bastiana  SYNONCHIA Enoplus 

BOLBINIA ,  Laxus  MESONCHIA Fimbrilla  (?) 

CYTOLAIMIA. ..  Monhystera  APONCHIA Chromadorella 

ISOLAIMIA Rhabdolaimus  TRIPLONCHIA Tylenchus 

POLYLAIMIA.. .  Bathylaimus,  Plectus      AXONCHIA Dorylaimus 

APODONTIA.. . .  Axonolaimus  ANAXONCHIA Oncholaimus 

SYNODONTIA..  Teratocephalus 

The  above  linear  tabular  arrangements  of  the  orders  do  not  bring 
out  fully  the  natural  relationships  of  the  different  groups.  These 
relationships  will  be  discussed  more  fully  later. 

While  the  nomenclature  here  proposed  is  dominated  by  a  few  linguis- 
tic roots,  it  of  course  by  no  means  follows  that  in  assigning  genera  to 
the  orders  designated,  due  attention  should  not  be  given  to  other  por- 
tions of  the  anatomy  than  those  indicated  by  the  nomenclature.  This 
is  a  commonplace  of  taxonomy.  The  relationships  of  an  organism  are 
fully  disclosed  only  on  consideration  of  all  its  parts,  and  undue  weight 
given  to  a  particular  feature  will  here,  as  elsewhere,  result  in  confusion. 


ONE  HUNDRED  NEW  NEMAS 

(Type  Species  of  100  New  Genera) 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY,  IX 

BY  N.  A.  COBB 

The  arrangement  of  the  genera  in  the  following  pages  will  serve, 
to  a  considerable  extent,  to  define  and  illustrate  the  orders  proposed 
on  page  214.  This  is  especially  true  of  all  except  the  Litinia,  Bol- 
binia,  Mesonchs  and  Aponchs.  In  each  order,  a  genus  has  been 
selected  and  given  a  name  philologically  connected  with  that  of  the 
order,  in  fact,  the  singular  of  the  order  name,  and,  in  most  cases, 
these  genera  may  be  considered  as  genera  typical  of  the  orders, — for 
instance,  Axonchium  may  be  taken  as  typical  of  the  order  Axonchia. 

So  far  as  it  is  found  advisable  to  accept  the  classification  proposed,  it 
might  be  well  to  keep  in  mind  in  the  establishment  of  the  many  new 
genera  which  the  future  will  undoubtedly  disclose,  the  application  of 
similar  names  to  those  genera  which  most  nearly  represent  the  average 
structure  of  the  order.  In  carrying  out  this  idea,  such  names  as  Cyto- 
laimella,  Isolaimella,  and  other  derivatives  at  once  suggest  themselves. 

It  is  already  becoming  evident  that  some  of  these  groups  may  prob- 
ably early  be  advantageously  subdivided;  e.g.,  Cytolaimia,  Anaxonchia. 
In  case  of  subdivision,  the  principles  alluded  to  in  the  footnote  to  page 
213  might  lead  to  some  such  action  as  the  following:  Amending  the 
definition  of  the  existing  order  and  segregating  the  new  order,  and  util- 
izing for  the  new  order-name  the  roots  already  suggested  (see  p.  214, 
lines  27-28)  together  with  appropriate  prefixes.  This  would  result  in 
building  up  a  comparatively  simple,  rather  homogenous  and  character- 
istic nomenclature  for  the  nema  phylum. 

In  each  order  the  genera  are  arranged  somewhat  in  accordance  with 
their  relationships.  Genera  of  doubtful  relationship  are  usually  placed 
near  the  beginning  or  near  the  end  of  the  order  series,  and  not  infre- 
quently appear,  in  the  light  of  our  present  knowledge,  to  be  intermedi- 
ate, or  indeterminate,  forms.  "Thus,  Rhadinema  flexile  at  the  beginning 
of  the  Isolaimia,  p.  256,  is  doubtfully  placed,  and  may  be  a  cytolaim; 
so  Nannolaimus,  p.  255,  may  perhaps  be  a  litinian  form.  Most  of  the 
order  series  present  these  special  cases. 

217 

WAVEHLY  PRESS,  BALTIMORE,  Nov.  1,  1920. 


218  KEY   AND   CHARACTERS 

PHARYNX  ABSENT,  or  so  obscure  as  easily  to  escape  notice*  New  Genera 

Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both 
Amphids  none,  so  far  as  known;  or  difficult  to  see  and  therefore  easily  overlooked 
Lateral  wings  to  cuticle  present;  naked;  striae  fine;  spinneret  none;  pharynx  obscure 
Mouth  depr.;  faint  apophyses  in  pharyngeal  bulb;  -f-;  excretory  pore  behind  neck.Hyalaimus      13 
Mouth  not  depr.;  pharynx  obscure,  not  apophysate;  oesophagus  faintly  cephaloboid 
Head  with  papillae,  minute  lat.  markings  (amphids?) ;  exert,  pore  front  of  nerve  ring . Litonema      12 

Head  without  papillae  or  lateral  markings;  excretory  pore  behind  the  nerve  ring Choronema      14 

Lateral  wings  to  the  cuticle  none 

Spinneret  abs.;  naked;  oesoph.  faintly  cephaloboid;  striae  very  fine;  faint  wings . .  (Choronema')      14 
Spinneret  present;  cephalic  setae  present 


Amphids  invisible,  known  only  as  outlets  of  secretion;  striae  coarse;  setae  long.  (Leptoncmella)      21 
Amphids  tiny,  tubular,  labial,  forward-pointing,  easily  overlooked;  striae  plain 
Striae  fine;  male  postanal  tubular  organs  submedian ;  pharyngeal  swelling  present.  (Catanema)      56 


Striae  coarse;  pharyngeal  swelling  none;  cephalic  setae  4  or  more;  head  nonstriate 
Mouth  cavity  present,  very  small;  males  without  supp.  organs;  nema  10mm.  ..(Laxonema} 
Mouth  cavity  none ;  vent,  row  acornshaped  organs  toward  head ;  setae  numerous .  (Stilbonema) 


Amphids  present 

Form  of  the  amphids  more  9r  less  irregular,  symmetrical  to  at  least  one  line 

The  amphids  linear ;  cephalic  setae  12  +  6  small ;  striae  coarse ;  spinneret  present .  (Leptonemella)      21 
The  amphids  not  linear;  no  spinneret;  naked;  labial  region  with  papillae  only 
Winged ; '  f ;  striae  rather  coarse ;  amphids  semi-ellipses ;  oesoph .  faintly  cephaloboid .  lotalaimus      15 

Wings  none;  striae  very  fine;  amphids  with  large  internal  connections Bolbinium     16 

Form  of  the  amphids  spiral,  circular,  or  elliptical ;  spinneret  present 
Shape  of  the  amphids  distinctly  spiral;  striae  fine,  resolvable 

Pharynx  devoid  of  teeth;  head  expanded;  cephalic  setae  4;  body  setose Bplbonema     49 

Pharynx  with  3  minute  teeth;  setae  in  longitudinal  rows (Alaimonema)    107 

Shape  of  the  amphids  circular;  sometimes  small,  well  forward  on  the  head,  and  obscure 
Lateral  wings  present;  cephalic  setae  4;  amphids  large 

Striae  coarse,  altered  on  the  lateral  fields;  lateral  wing  distinct Antomicron      17 

Striae  fine,  not  altered  on  the  lateral  fields;  lateral  wing  faint Cyartonema      18 

Lateral  wings  none  or  faint 
External  amphid  circular,  at  least  apparently,  well  developed;  head  set  off 

Body  setose ;  amphids  really  spiral,  on  the  head ;  striae  rather  fine,  resolvable (Bolbonema)      49 

Body  naked;  amphid  circular 

Position  of  amphid,  on  head;  striae  fine;  contour  not  crenate;  wings  faint (Cyartonema)      18 

Position  of  amphid,  behind  head;  striae  coarse;  contour  crenate Cincionema      22 

External  amphid  minute,  on  the  front  of  the  head,  tubular,  easily  overlooked;  neck  2-5% 
Striae  fine;  male  postanal  tubular  organs  submedian;  rjharyn.  swelling  present. .  (Catanema)      56 
Striae  coarse,  plain;  cephalic  setae  4  or  more;  head  without  striae 

Mouth  cavity  very  small;  nema  10mm;  males  without  supplementary  organs. .  (Laxonema)      20 
Mouth  cavity  none;  cephalic  setae  in  3  or  more  circlets;  males  without  caudal  supplements 
Supplementary  organs  of  acorn  shape,  found  in  a  ventral  row  near  the  head. .  (Stilbonema)      1 
Supplementary  organs  none,  but  with  special  pre-  and  postanal submed.  setae .  (Stilbonema)      19 
Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling  of  palpable  size 
Amphids  none  so  far  as  known,  or  difficult  to  see  and  easily  overlooked 

Wings  10-42;  spinneret  present;  f=;  striae  fine,  plain;  ceph.  setae  6,  subceph.  4 Porocoma      11 

Wings  2,  if  any,  lateral  only,  in  any  case  faint 

Spinneret  abs.;  oesoph.  faintly  cephaloboid;  striae  very  fine;  no  setae;  faint  wings.  .(Choronema)      14 
Spinneret  present;  amphids  minute  if  any,  unclosed 

Female  organ  single,  -f ;  6  cephalic  papillae  only;  spinneret  doubtful;  nema  0.28  mm.  .Litotes 
Female  organs  double,  'f;  striae  fine,  plain;  cephalic  setae  4;  2  huge  somatic  glands. .  (lonema)       9 
Amphids  present 

Form  of  the  amphids  more  or  less  irregular,  often  symmetrical  to  at  least  one  line 
Contour  of  the  amphids  linear,  i.e.  long  and  narrow 

Lateral  wings  none ;  cephalic  setae  6,  subcephalic  4 ;  '  f Tycnodora       3 

Lateral  wings  present;  head  naked  or  its  setae  irregular;  spinneret  present 

Wings  prominent;  striae  coarse;  ' f ;  inconspicuous  pharynx  (?) (Actinonema)    117 

Wings  faint;  striae  fine;  -f-;  mouth  oblique Campylaimus       5 

•     Contour  of  the  amphids  not  linear 

Striae  interrupted  on  the  lateral  fields  by  wings,  plain 

Spinneret  absent;  oeosphagus  faintly  cephaloboid;  'f (lotalaimus)      15 

Spinneret  present;  oesophagus  narrow,  one  to  two-fifths  as  wide  as  neck 

Anterior  extremity  mitriform,  very  distinctly  set  off;  wings  to  the  cuticle  6-8 Xennella 

Ant.  extremity  not  mitriform;  coarse  c'uticular  elements  in  rows  like  tiles; '  f ' . .  (Ceramonema)      48 
Striae  uninterrupted,  fine,  plain;  spinneret  present;  slender  nemas,  up  to  1.2% 

Head  without  setae;  amphids  relatively  large  and  deep;  not  ocellate Schistodera       4 

Head  with  4  cephalic  setae;  amphids  small  with  obvious  internal  elements;  ocellate . Nemella      10 
Form  of  the  amphids  spiral,  circular,  or  elliptical  (doubtful  in  Litotes) 
Shape  of  the  amphids  spiral;  striae  resolvable,  not  altered  on  the  lateral  fields 

Spinneret  absent;  striae  coarse;  probably  f  (?);  contour  crenate (Alaimella)       7 

Spinneret  present;  striae  rather  coarse;  amphids  large 
Head  expanded;  lip-region  elevated,  not  papillate;  ceph.  setae  6  plus  10;  'f'.. .  (Nannolaimus)      36 

Head  not  expanded;  lips  6,  papillate;  cephalic  setae  4;  f  (?) Alaimella      7 

Shape  of  the  amphids  circular  or  elliptical;  spinneret  present  except  perhaps  in  Litotes 
Lateral  wings  perhaps  pres.;  f ;  striae  plain;  lipless;  pharynx  very  minute,  conoid. .  Nemanema       2 
Lateral  wings  none  (or  very  faint);  head  rounded;  striae  none,  or  very  fine 
Cephalic  setae  ten  or  more,  in  two  circlets 

Contour  of  amphids  unclosed  behind;  setae  12,  4  subcephalic;  mouth  a  mere  pore . TMinium  f  8 
Contour  of  amphids  closed;  setae  10,  no  subcephalic ;  pharynx  minute,  conoid.  (Linhomoella)  35 
Cephalic  setae  none,  or  small  (4  or  6) 

Setae  4,  small;  ocellate;  amphids  small,  labial,  unclosed;  body  contains  huge  glands. lonema  9 
Setae  none;  nemas  of  very  simple  structure;  wings  none  or  doubtful 

Papillae  representing  6  setae;  amphid  (?)  minute;  -f ;  nema  0.28  mm;  width  5%.  .Litotes        1 
Papillae  none ;  amphids  fairly  developed,  closed ;  f ' ;  nema  2.5mm;  width  1 .4% .  (Nemanema)       2 
*For  abbreviations  used  in  the  Key,  see  foot-note  p.  223. 


KEY  AND   CHARACTERS  219 

PHARYNX  PRESENT  New  Genera 

Wall  of  the  pharynx  unarmed  (for  alternative  see  page  221,  midway) 
Cavity  of  the  pharynx  conoid,  or  irregular 
Oeosphagus  with  median  or  posterior  swelling  or  both 
Amphids  none,  or  obscure;  striae  plain,  not  altered  on  the  lateral  fields 

Spinneret  none ;  head  subtruncate,  naked ;  contour  almost  imperceptibly  crenate .  Cephalobellus      23 
Spinneret  present 

Striae  coarse;  pharynx  minute  (none?)  without  swelling;  head  non-striated. . . .  (Leptonemella)      21 
Striae  fine;  pharynx  narrow,  enclosed  in  a  swelling;  amphids  minute  labial  tubes .  (Catanema)      56 
Amphids  present 

The  amphids  linear;  pharynx  (?) ;  striae  coarse,  plain;  no  wings;  setae,  3  circlets . .  Leptonemella      21 
The  amphids  spiral,  circular,  or  elliptical;  when  tubular,  surface  contour  circular 
Form  of  the  amphids  a  distinct  spiral;  spinneret  present 

Striae  coarse;  oesophagus  =*=  oxyuroid;  wings  8;  cephalic  setae  6,  subcephalic  4. .  ..Dasynema     34 
Striae  fine,  plain 

Lateral  wings  only  on  tail  of  male; '  f ;  pharynx  somewhat  zigzag;  setae  minute. .  (Zalonema)  7 
Lateral  wings  absent 

Head  with  numerous  scattered  setae ;  pharynx  small,  narrow ;  onchi  vestigial .  (Alaimonema)  107 
Head  not  with  numerous  setae;  pharynx  fairly  well  developed;  teeth  unobvious;  'f 

Cheeks  thickly  outinized ;  cuticle  thick Zalonema      57 

Cheeks,  if  thick,  not  heavily  cutinized ;  lips  2,  large,  lateral Pseudonchus      58 

Form  of  the  amphids  a  circle  or  ellipse;  striae  unaltered  laterally 
Spinneret  absent;  striae  fine 
Intestinal  cells  with  crystals;  6  lips,  appendiculate;  -f ;  cephalic  setae  10. ...  (Crystallonema)      67 

Intestinal  cells  not  with  crystals;  lips  none;  -f-;  cephalic  setae  papilloid Anlicyathus      24 

Spinneret  present 
Head  swollen,  unstriated;  no  pharyngeal  swelling;  striae  coarse,  plain 

Cephalic  setae  4;  lips  none;  no  labial  papillae;  amphids  a  single  circle (Cinctonema)      22 

Cephalic  setae  none;  lips  6,  unipapillate;  amphids  two  concentric  circles. . .  .Micromicron    104 
Head  not  swollen  or  set  off;  pharyngeal  swelling  anon  present;  striae  fine,  plain 
Pharynx  narrow;  amphids  minute;  male  postanal  organs  tubular;  setae  4  +  6.  (Calanema)      56 
Pharynx  capacious;  amphids  well  developed,  opposite  the  pharynx  or  behind  it 

Lips  2,  lateral;  pharyngeal  ridges  simulate  teeth;  'f ;  cephalic  setae  4 (Pseudonchus)      58 

Lips  6,  each  with  a  digitate  appendage;  cephalic  setae  10 (Crystallonema)      67 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling 
Amphids  irregular 

Spinneret  none;  striae  unaltered  laterally;  -f-;  spiral  amphid  placed  on  a  deltoid  p&rt.Didelta      33 
Spinneret  present 

Striae  altered  laterally ; '  f ' ;  head  naked,  set  off;  cuticle  thick ;  pharynx  armed  (?)  .(Actinonema)    117 
Striae  not  altered  on  the  lateral  fields 

Cephalic  setae  12  +  6,  in  two  circlets;  -f ;  amphid  inconspicuous Leplogastrclla      28 

Cephalic  setae  6,  in  one  circlet;  amphid  1  the  width  of  the  head;  spinneret  (?) .  .Rhabdocoma      32 
Amphids  spiral,  circular,  or  elliptical 
The  amphids  in  the  form  of  a  spiral;  striae  not  altered  on  the  lateral  fields 

Spinneret  none  (?) ;  amphid  J  the  width  of  the  head;  naked;  wings  two Neurella     25 

Spinneret  present 

Buccal  cavity  with  cutinous  frame,  and  3  apophyses  with  small  apical  teeth. .  (Trogolaimus)  75 
Buccal  cavity  without  distinct  framework  and  without  teeth  of  any  kind;  striae  fine 

Ovaries  'f;  striae  resolvable;  amphid  of  4  winds;  cephalic  setae  6  +  10 Nannolaimus     36 

Ovaries  -f-;  striae  plain;  amphids  simulating  a  circle 

Mouth  cavity  large  and  obvious;  cephalic  setae  unknown,  in  any  case  few Margonema     27 

Mouth  cavity  small;  head  rounded;  cephalic  setae  large,  4  (special)  plus  6. . .  .Linhomoella      35 
The  amphids  in  the  form  of  circles  or  ellipses 
Striae  altered  on  the  lateral  fields  by  wings:  spinneret  present 

Head  set  off  by  a  groove,  its  appendages  varied ;  striae  coarse ;  wings  numerous . .  Xenolaimus  30 
Head  not  strongly  set  off,  though  usually  well  developed 

Ovaries  reflexed,  f ;  naked;  striae  fine,  plain;  pharynx  small,  obsolescent. . . .  (Nemanema)        2 
Ovaries  outstretched;  pharynx  well  developed,  but  not  large;  cephalic  setae  present 
Striae  fine,  plain;  cephalic  setae  6,  segmented;  -f- (Cytolaimium)     31 

Cuticle  rough  from  subdivided  wings;  setae  many;  lips  3,  mandibulate  (?).... (Xyala)      72 
Cuticle  normal;  lips  6,  papillate,  appearing  somewhat  fimbriate;  striae  plain . Daptonema     66 
Striae  not  altered  on  the  lateral  fields 

Spinneret  absent;  striae  fine,  plain;  female  organs  outstretched,  except  Rhabdocoma 
Ovaries  two,  -f- 

Cephalic  setae  6,  plainly  segmented;  lips  three,  papillate Cytolaimmm     3 

Cephalic  setae  4,  not  segmented;  lip-region  punctate,  amalgamated Didelta     33 

Ovary  one,  subcephalic  setae  4 

Cephalic  setae  6:  f ' ;  lips  3,  flattish,  not  digitate Rhabdocoma     32 

Cephalic  setae  10;  -f ;  lips  6,  small,  digitate 
Cells  of  intestine  with  crystals;  amphids  not  raised;  excretory  pore  labial  Crystallonema     67 

Cells  of  intestine  without  crystals;  amphids  raised;  tail  with  spicate  setae Zanema     68 

Spinneret  present 

Pharynx  obscure  „ 

Lips  in  two  sets,  outer  large,  low;  inner  soft  extensions  of  the  oesophagus.  .JygonemeUa  W 
Lips  not  in  2  sets,  amalgamated;  ceph.  setae  4, 3-jointed;  phar.  prismoid  cup.(Rhadinema)  tf 
Pharynx  more  or  less  obvious;  striae  plain 

Female  organs  reflexed,  f;  striae  fine;  head  naked;  pharynx  small (Memanema)       £ 

Female  organs  outstretched 

Mouth  cavity  small,  inconspicuous;  cephalic  setae  4  (special)  plus  6  . . .  (Linhomoella)  35 

Mouth  cavity  moderate ,  in  a  swelling ;  ceph .  setae  6 ,  plainly  segmented ;  -f- .  Cytolaimium  31 
Ovary  one,  -f;  striae  coarse;  setae  12;  lips  6,  striate 

Lips  conoid,  striated,  large,  tipped  with  setae,  and  with  a  seta  near  base.  Dactylaimus  / 

Lips  flat,  papillate,  appearing  fimbriate,  three-ribbed (Daptonema)  66 

Cavity  of  the  pharynx  more  or  less  prismoid  or  cylindroid  (not  conoid  or  very  irregular) 


220  KEY    A.ND    CHARACTEES 


Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both 
Amphids  none  so  far  as  known,  or  diflicult  to  see  and  easily  overlooked 
Lateral  wings  present;  spinneret  absent 

Striae  none;  wings  2;  naked;  pharynx  like  oesophagus  lumen (Litonema)      12 

Striae  fine;  wing  1;  seta-like  papillae  6;  pharynx  contains  glottoid  organ Cephalobium      54 

Lateral  wings  absent;  striae  plain 
Spinneret  present 

Striae  very  coarse;  phar.  cupshaped;  nema  10mm;  male,  no  supplement,  organs.  (Laxone.ma)  20 
Striae  fine;  phar.  small,  enclosed  in  bulb;  male  postanal  tub.  organs  submedian. .  (Catanema)  56 
Spinneret  absent;  setae  none 

Phar.  very  long,  nar.,  ending  in  cylindroid  bulb;  'f';  nema  1mm;  lips  conoid  Myctolaimus      61 

Pharynx  very  short;  cardiac  bulb  oblate  or  spherical;  f" 

jNema  3.3mm;  width  9%;  pharyngeal  apophyses  present;  oesophagus  clavate .Blattophila      55 
Nema  6mm;  width  3%;  pharyngeal  apophyses  absent;  oesophagus  cylindrical. Protrellus      38 
Amphids  present. 

The  amphids  are  somewhat  irregular,  symmetrical  to  one  line;  striae  fine,  plain;  wingless 
Form  of  amphids  not  lin.;  no  spinneret;  naked;  lips  6;  phar.  tub.;  amphids  large. Colpurella      39 
Form  of  amphids  linear 

Ovary  one,  'f ;  spinneret  absent;  cephalic  setae  6  plus  4;  pharynx  tubular. . . .  (Myolaimus)      60 
Ovaries  two,  -f-;  spinneret  present;  ceph.  setae  4;  ventral  (?)  onchus  near  mouth. Pseudolella      53 
The  amphids  are  spiral,  circular,  or  elliptical 
Shape  of  the  amphids  a  distinct  spiral 

Striae  coarse;  oesoph.=toxyuroid;  wings  8;  ceph.  setae  6,  subceph.  4;  head  unstr. .  (Dasynema)  34 
Striae  fine 

Lateral  wings  present;  striae  plain;  spinneret  present;  head  thick-walled. . .  .Pycnolaimus  40 
Lateral  wings  absent 

Spinneret  none;  -f-;  cephalic  setae  10,  subcephalic  4;  pharynx  obscure Laimella     44 

Spinneret  present 

Phar.  armed  in  front  with  3  obscure  equal  teeth;  setae  numerous  on  head. .  (Alaimonema)    107 
Pharynx  without  teeth ;  head  rounded 

Lips  2,  lateral;  'f;  striae  plain;  pharyngeal  ridges  simulating  teeth (Pseudonchus)      58 

Lips  none,  or  very  indistinct 

Cephalic  setae  10.  subcephalic  4;  pharynx  obscure,  has  minute  onchus Laimtlla      44 

Ceph.  setae  four  ?  (or  none);  lips  set  off;  phar.  2-chamb.,  2d  tapering  (Polylaimium)      59 

Shape  of  the  amphid  circular  or  elliptical  (anon  tubular) ;  striae  unaltered  laterally 
Spinneret  absent;  striae  plain,  fine 

Ovary  one,  -f ;  ceph.  setae  10,  subceph.  6;  amphids  circular;  pharynx  broad.  (Crystallonema)  67 
Ovaries  two 

Cuticle  naked;  spear  (?)  minute;  ceph.  setae  0,  6  pap.;  amphids  ellip.;  T. .  (Tripltmchium)      80 
Cuticle  not  naked;  without  spear;  ceph.  setae  present;  amphids  circular;  -f-.  Anticyathux      24 
Spinneret  present 

Buccal  cavity  very  small  and  easily  overlooked;  cephalic  setae  present;  striae  plain 
Striae  coarse;  phar.  minute,  cupshaped;  males  without  supplementary  organs , Laxonema      20 
Striae  fine;  phar.  narrow,  bulbed;  males  with  postanal  rows  of  tubular  organs. Catanem a      56 
Buccal  cavity  very  long;  'f;  striae  fine;  cephalic  setae  small  or  none 
Cephalic  setae  four  (?)  or  none ;  amphids  large,  deep ;  pharynx  2-chambered. . .  Polylaimium      59 

Cephalic  setae  10,  short;  amphids  small;  ocellate;  pharynx  very  long (Catalaimus)      89 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling 
Amphids  none  so  far  as  known,  or  difficult  to  see  and  easily  overlooked 

Wings  present;  spinneret  present;  striae  fine;  ovaries  two,  f=;  phar.  vestigial.  .(Porocoma)      11 
Wings  absent;  striae  fine 

Ceph.  setae  10,  long,  segmented;  lips  6,  thin,  each  with  seta;  amphid  minute  slit. .  (Trilepta)      92 
Cephalic  setae  none,  or  not  long  or  obviously  segmented;  lips  without  setae,  or  lipless 
Buccal  cavity  tubular;  spinneret  absent;  'f;  lipless;  papillae  depressed. ...  (Isolaimium)      41 
Buccal  cavity  not  long  and  tubular;  spinneret  present 
Ceph.  setae  10;  lips  6,  obvious;  dorsal  phar.  element  bent  in  at  lips;  'f  (?) . .  (Asymmetrella)      70 

Cephalic  setae  6,  papilloid;  lipless;  -f (Litotes)        1 

Amphids  present 

Structure  of  the  amphids  more  or  less  irregular,  usually  symmetrical  to  at  least  one  line 
Contour  of  the  amphids  linear;  striae  not  altered  on  the  lateral  fields 

Ceph.  setae  long,  segmented;  lips  6,  thin,  each  with  seta;  amphid  minute  slit.  .(Trilepta)  92 
Cephalic  setae  none,  or  not  long  and  not  obviously  segmented 

Spinneret  absent;  'f;  striae  fine;  phar.  tub.;  lips  confluent;  papillae  depressed.  .Isolaimium  41 
Spinneret  present;  female  sexual  organs  double;  striae  fine 

BUG.  cavity  tub.;  amphids  long;  striae  resolve;  onchus  ventral  (?),  obscure. .  (Pseudolella)  53 
Buccal  cavity  not  tubular;  amphids  more  or  less  stirrup  form;  striae  not  resolvable 

Ocellate;  cephalic  setae  none;  lips  faint;  amphids  distinct,  though  small (lllium)      45 

Ocelli  0;  setae  10;  cutinized  dorsal  pharyn.  element  bent  inward  at  lips. .  (Asymmetrella)      70 
Contour  of  the  amphids  not  linear 
Striae  altered  on  the  lateral  fields;  ovaries  two,  reflexed;  spinneret  present 

Lateral  wings  present;  striae  coarse,  like  rows  of  tiles;  pharynx  narrow  Ceramonema     48 

Lateral  wings  none;  striae  fine,  plain;  onchia  vestigial;  six  cervical  glands.  (Anoncholaimus)      93 
Striae  not  altered  on  the  lateral  fields,  fine 
Spinneret  none 

Cephalic  setae  4,  forward-pointing;  amphids  more  or  less  deltoid (Didelta)      33 

Cephalic  setae  0;  amphids  more  or  less  reniform Colpurella      39 

Spinneret  present 

Cheeks  thickly  cutinized;  head  conoid;  small  forward-pointing  onchia  (?) . (Isonemella)    109 
Cheeks  not  thickly  cutin.;  head  not  prom,  conoid;  no  small  onchia  exc.  in  Anoncholaimus 
Ovaries  outstretched,  -f-;  ocellate;  phar.  tubular;  nearly  lipless;  ceph.  setae  4.  (Coinonema)      42 
Ovaries  reflexed,  'f;  striae  fine,  plain;  pharynx  not  tubular;  head  truncate 

Cephalic  setae  none;  ocellate;  lips  faint;  amphids  distinct,  though  small lllium      45 

Cephalic  setae  10;  ocelli  none;  amphids  indistinct 

Dorsal  cutinized  element  of  the  pharynx  bent  inward  at  the  lips (Asymmetrella)      70 

Dorsal  wall  of  the  pharynx  not  differentiated;  onchia  minute (Anoncholaimus)      93 

Structure  of  the  amphids  spiral,  circular,  or  elliptical 


KEY    AND    CHARACTERS  221 

Form  of  the  amphids  a  distinct  spiral;  spinneret  present 

Winged;  'f ;  striae  coarse,  plain;  spinneret  heavily  cutinized;  cephalic  setae  4 Cynura      46 

Wings  none;  female  sexual  organs  double;  striae  fine,  plain 

Ovaries  reflexed;  no  lips;  pharynx  none  or  nearly  obsolete;  osellate (lonema)        9 

Ovaries  outstretched,  -f-;  cephalic  setae  4;  pharynx  tubular,  narrow 
Spiral  amphid  of  one  wind,  somewhat  hook-form;  ocellate;  pharynx  obscure.  .Coinonema      42 

Spiral  amphid  of  several  winds;  not  ocellate;  pharynx  well  developed Xinema      47 

Form  of  the  amphids  circular  or  elliptical 
Striae  interrupted  on  the  lateral  fields;  lateral  wings  present;  spinneret  present 

Female  organs  single, -f;  amphids  2  concentric  circles;  setae  in  groups  of  3 (Omicronema)      50 

Female  organs  double,  'f;  amphids  not  2  concentric  circles;  setae  not  in  groups 

Spinneret  heavily  cutinized;  cephalic  setae  4;  amphids  really  spiral (Cynura)      46 

Spinneret  simple,  normal;  cephalic  setae  10;  amphids  small,  elliptical (Anoncholaimus)      93 

Striae  not  interrupted  on  the  lateral  fields 
Spinneret  none;  striae  fine,  plain 

Ovaries  2,  -f-;  setae  4;  amphids  more  or  less  deltoid;  phar.  irregularly  napiform. .  (Didelta)      33 
Ovary  1,  outstretched;  amphids  not  deltoid 

Amphids  very  small;  ceph.  setae  in  3  circlets  of  6;  f-;  cuticle  reticulated. . .  .Halanonchus     51 
Amphids  large;  setae  10,  with  6  subcephalic;  -f;  lips  with  digitate  processes 

Intestinal  cells  with  crystals;  caudal  setae  none;  amphids  not  raised (CrystaUonema)      67 

Intest.  cells  without  crystals;  amphids  raised;  about  10  thorn-like  caudal  setae .  (Zanema)      68 
Spinneret  present 

Ceph.  setae  in  3s;  coarse,  transverse  striae  resolvable  into  elongated  elements.  .Omicronema     50 
Cephalic  setae  not  in  groups;  striae,  if  resolvable,  not  into  elongated  elements 
Buccal  cavity  more  or  less  obscure,  easily  overlooked;  wings  none 

Ceph.  setae  4,  3-jointed;  lips  confluent;  amphid  i  wide  as  trunc.  head,  closed. Rhadinema      37 
Cephalic  setae  6  or  more,  minute  or  papilloid 

Lips  none;  amphid  (?)  unclosed  behind,  minute;  head  rounded;  -f (Litotes)        1 

Lips  soft  and  rather  obscure;  amphid  fairly  well  developed,  closed (Zygonemella)      26 

Buccal  cavity  obvious;  setae  only  in  Halinema  long,  then  twice  as  long  as  head  is  wide 
Ocelli  present;  ceph.  cuticle  thick;  head  distinctly  conoid;  minute  onchia  (?)  .Isonemella    109 
Ocelli  none;  cephalic  cuticle  not  thickened;  head  not  distinctly  conoid;  no  onchia 

Ovaries  two,  '  f ' ;  striae  fine,  plain ;  onchia  vestigial ;  6  cervical  glands Anoncholaimus      93 

Ovary  one,  -f ;  striae  usually  rather  coarse;  pharynx  quite  unarmed 

Head  end  diminished  to  form  a  sort  of  beak;  pharynx  tubular Rhynchonema      43 

Head  end  not  diminished  to  form  a  beak;  pharynx  not  tubular 

Setae  and  amphids  large;  phar.  shorter  than  head  is  wide;  caudal  setae  pres. .  Halinema      52 
Setae  and  amphids  medium  size ;  lips  conoid ,  tips  with  minute  ' '  claws' ' .  (Dactylaimus)      29 
Wall  of  the  pharynx  armed  with  teeth  or  onchia 

Armature  spear-like;  caudal  glands  and  spinneret  typically  (usually)  absent 
Spear  with  a  bulbous  base;  striae  fine,  plain 

Oesophagus  plain,  faintly  cephaloboid;  -f ;  cuticle  with  wings Aphelenchulus      81 

Oeosphagus  with  a  posterior  bulb  or  swelling;  cuticle  without  wings 
Amphids  ellip.,  well  devel.  internally;  '  f ' ;  spear  faint;  lips  6,  faint,  unipapillate.  Triplonchium      80 

Amphids  linear,  transverse;  oesophagus  dorylaimoid;  f';  no  labial  papillae Doryllium      84 

Spear  plain,  i.e.,  without  bulbous  base;  striae  fine,  nearly  always  plain 
Oesophagus  plain,  i.e.  without  median  or  posterior  swelling;  spinneret  present 
Amphids  0;  -f ;  cephalic  setae  0;  head  truncate;  lip-region  set  off;  spear  small "  prod" .  lotonchium      82 
Amphids  present;  lip-region  not  set  off 

Amphids  symmetrical  to  one  line  only;  setae  10;  pharynx  long;  spear  toothlike  (Catalaimus)      89 
Amphids  spiral,  sometimes  faint;  'f;  striae  unaltered  laterally;  cephalic  setae  4 
Ocellate;  amphids  labial;  "spear"  slender  in  nar.  phar.;  lips  and  papillae  none.Onchulella      87 

Ocelli  none;  lips  3,  papillate;  "spear"  toothlike,  in  an  open  cavity (Digitonchus)      95 

Oesophagus  with  posterior  swelling  which  sometimes  occupies  5  the  neck 

Spinneret  present ;  amphids  spiral  (?) ;  eyes  present ;  ceph .  setae  4 ;  lipless Onchium      83 

Spinneret  none;  striae  fine 
Amphids  0;  -f ;  no  ceph.  setae;  head  truncate;  lip-region  set  off;  speara  small  prod. lotonchium      82 

The  amp^Tds "lliptical ;  spear-tip  bent ;  ' f ;  lips  6,  bipapillate Campydora      88 

The  amphids  symmetrical  to  one  line  only;  lips  set  off  by  constriction 

Female  organs  double,  f ;  spear  long  and  very  slender;  pre-rectum  very  long. .  .Leptonchus      85 
Female  organ  single,  f;  spear  short,  not  slender;  pre-rectum  short 

Posterior  oesophageal  swelling  short,  not  set  off  by  constriction  in  front. . . .  (Doryllium) 
Posterior  oesophageal  swelling  long,  set  off  by  constriction  from  previous  part.  Axonchium      t 

Tooth  one  (for  alternative  see  top  Page  223:  "Teeth  two—" 

Oesophagus  with  a  median  or  posterior  bulb  or  swelling,  or  both  (for  alternative  see  Page  222) 
Amphids  none  or  unknown,  or  so  inconspicuous  or  faint  as  to  be  difficult  to  see 
Striae  fine,  plain;  spinneret  none;  'f ;  naked;  lips  6,  bipapillate;  spear  bent  at  apex. Campydora      t 
Striae  altered  on  the  lateral  fields 
Wingless;  spinneret  present;  onchulus  with  large  dorsal  muscle;  setae  small. . . .  (lotadorus)    115 

s'piMerefpresent;  striae  coarse,  resolvable;  'f ;  lips  retractile;  setae  4 (Ptycholaimellus)     116 

Spinneret  absent;  striae  fine,  plain;  '  f ;  lips  not  retractile,  naked;  spear  bent. .  (Campydora)      £ 

sTnicturfofamphids  more  or  less  irreg.,  often  symmetrical  to  one  line  (for  alternative  see  Page  222) 
Contour  of  the  amphids  not  linear;  spinneret  present 

Striae  altered  laterally;  onchus  small,  well  forward;  setae  obscure;  lips  12 lotadorus    115 

Striae  unaltered  laterally;  'f  ,  Qa 

Setae  fasciculate;  cuticle  thick;  lips  faint jiantnoaora 

Setae  not  fasciculate;  cuticle  notthick _......... Bolbella      £ 

Contour  of  the  amphids  linear;  appearing  as  transverse  slits  opposite  the  pharynx 
Striae  altered  laterally;  spinneret  present;  'f;  striae  coarse,  resolvable 


2  KEY   AND    CHARACTERS 

New  Genera 

Lip-region  retractile;  cephalic  setae  4,  rather  obviously  segmented Ptycholaimellus    116 

Lip-region  non-retractile;  cephalic  setae  10,  not  obviously  segmented Rhips    118 

Striae  not  altered  laterally,  or  very  little;  cephalic  setae  10 

Lips  thin  and  flap-like;  cephalic  setae  long  and  obviously  segmented Trilepta     92 

Lips  not  thin  or  flap-like;  cephalic  setae  shorter,  not  obviously  segmented;  'f 
Striae  resolvable ;  pharynx  not  subdivided ;  onchus  not  spear-like ;  no  cervical  setae .  Rhips    118 
Striae  plain ;  pharynx  in  distinct  chambers ;  onchus  spear-like ;  cerv.  setae  long .  (Bolbella)      90 
Structure  of  the  amphids  spiral,  circular,  or  elliptical 

Form  of  the  amphids  more  or  less  distinctly  spiral;  spinneret  present,  doubtful  in  Laimella 
Striae  altered  on  the  lateral  fields;  cephalic  setae  4 

Wings  present;  striae  fine,  resolvable;  lips  6,  confluent,  bipapillate;  -f- Pepsonema     77 

Wingless;  tooth  with  apophysis  faintly  y-shaped;  striae  coarse;  amphids  labial. .  Ypsilon     96 
Striae  not  altered  on  the  lateral  fields 

Onchus  one,  with  its  apophysis  somewhat  y-shaped;  striae  coarse;  setae  4 Ypsilon     96 

Onchus  not  y-shaped,  often  with  small  companions 
Amphids  distinctly  spiral 
Setae  0;  body  striated  (exc.  head);  pharyn.  bulb  faint,  cardiac  napiform.  .Amphispira    103 

Setae,  cephalic  10,  subcephalic  4;  non-striated;  -f-;  onchus  spear-like (Laimella)     44 

Amphids  appearing  circular 

Lips  12-fold;  onchus  somewhat  spear-like;  cephalic  setae  small,  6  plus  10-12.  .Mesodorus    105 
Lips  faint,  not  over  6;  onchus  not  spear-like 

Ovaries  -f-;  phar.  bulbous;  amphids  circular  (?);  setae  6  +  6;  striae  fine .  (Bolbolaimus)    100 
Ovaries  reflexed,  'f 

Striae  fine,  plain;  onchuli  minute;  lips  faint,  6;  papillae  conical;  setae  4. .  (Polysigma)    106 
Striae  coarse;  head  not  striated;  cuticle  thick;  cephalic  setae  fasciculate.  .Xanthodora     98 
Form  of  the  amphids  circular  or  elliptical 
Striae  altered  on  the  lateral  fields;  spinneret  present 

Wingless;  labial  amphids  elliptic;  striae  resolvable;  pharyngeal  bulb  one-sided. lotadorus  115 
Wings  present;  striae  coarse 

Female  sexual  organs  single,  -f ;  cephalic  setae  4,  labial  setae  6;  wings  numerous.  .Nudora  113 
Female  sexual  organs  double,  'f 

Head  expanded,  naked;  striae  not  retrorse;  tooth  small;  lips  minute,  obscure . Xenonema    102 
Head  not  expanded,  its  setae  4 ;  lips  obvious;  striae  appar.  retrorse  throughout. Rhinema    114 
Striae  not  altered  on  the  lateral  fields 
Cephalic  setae  none 

Head  hemispher . ,  expanded ;  lips  6 ,  conoid ;  spinneret  pres . ;  onchus  obscure .  (M icromicron)  104 
Head  not  expanded;  lips  set  off,  confluent;  no  spinneret;  'f ;  "spear"  bent. .  (Campydora)  88 
Cephalic  setae  and  spinneret  present 

Onchus  spear-like;  amphids  resemble  concentric  circles;  setae  in  2-3  rows (Mesodorus)    105 

Onchus  not  spear-like;  amphids  not  concentric  circles;  setae,  if  numerous,  fascicled 
Female  sexual  organs  outstretched 

Ovaries  two;  cephalic  setae  6+6;  submedian  onchia  present (Bolbolaimus)     100 

Ovary  single;  ceph.  setae  4;  submed.  onchia  none  or  vestigial Synonema    110 

Female  sexual  organs  reflexed,  'f;  amphids  really  spiral 

Submedian  onchi  present;  labial  papillae  conical;  setae  4;  striae  fine (Polysigma)    106 

Submedian  onchi  abs.;  setae  in  fascicles;  head  non-striated;  cuticle  thick .  (Xanthodora)      98 
Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling;  amphids  present 
Form  of  the  amphids  more  or  less  irregular,  usually  symmetrical  to  at  least  one  line 
The  amphids  linear;  spinneret  present;  'f;  striae  coarse,  altered  laterally 

Striae  plain;  head  naked,  set  off  by  constriction;  wing  1,  prom.;  cuticle  thick.  .Actinonema  117 
Striae  resolvable  into  rods;  ceph.  setae  10;  wingless;  amphid  5-6  times  as  wide  as  long. Rhips  118 
The  amphids  not  linear;  striae  not  altered  on  the  lateral  fields 

Head  conoid;  cheeks  thick;  ocellate;  onchus  minute;  phar.  narrow;  setae  10 (Isonemella)    109 

Head  not  conoid;  cuticle  of  the  cheeks  not  thick;  'f;  striae  fine,  plain 

Spinneret  absent;  lips  6,  unipapillate;  cephalic  setae  6;  amphid  behind  pharynx . Onchulus  94 
Spinneret  present 

Buccal  cavity  extending  beyond  the  nerve-ring;  onchus  spear-like;  ocellate. Catalaimus     89 
Buc.  cavity  not  unusually  long,  its  dors,  element  bent  at  lips;  not  ocellate.  Asymmetrella     70 
Form  of  the  amphids  spiral,  circular,  or  elliptical 

The  shape  of  the  amphids  a  more  or  less  distinct  spiral ;  spinneret  present ;  '  f '  or  -f 
Striae  altered  laterally,  fine,  resolvable;  wings  present;  cephalic  setae  10;  'f.  .Acanthonchus    101 
Striae  not  altered  on  the  lateral  fields,  coarse,  plain 

Spinneret  unknown,  abs.  (?);  -f ;  setae  10;  onchi  submedian ;  contour  crenate.  .(Gonionchus)  97 
Spinneret  present;  T 

Lips  three;  setae  6;  amphids  labial;  onchus  digitate Digitonchus     95 

Lips  more  than  3 ;  setae  num . ,  scattered ;  amphids  not  lab . ;  onchi  more  than  1 .  (Croconema)    112 
The  shape  of  the  amphids  circular  or  elliptical 

Striae  altered  laterally;  wings  numerous  with  retroree  bristles;  cephalic  setae  4.. Rhinema    114 
Striae  not  altered  on  the  lateral  fields 
Head  conoid;  cephalic  setae  10;  spinneret  present 

Ocelli  none;  'f;  rear  portion  of  oesoph.  succession  of  bulbs;  striae  fine,  plain.  (Bolbella)      90 
Ocelli  present;  no  succession  of  bulbs  in  the  posterior  part  of  the  oesophagus 
Cheeks  thick;  onchus  appressed,  minute;  pharynx  rather  long  and  narrrow .  (Isonemella)    109 
Cheeks  not  thick;  onchus  digitate,  well  developed  ;pharynx  not  narrow,  short .  Cophonchus    108 
Head  not  conoid;  not  ocellate;  pharynx  not  long  and  narrow 

Spinneret  unknown;  amphids  spiral;  -f ;  setae  10;  onchi  submed.;  contour  cren. (Gonionchus)  97 
Spinneret  present 

Onchi  3,  clustered;  phar.  unobv.;  setae  scattered;  cuticle  thick ;  contour  cien..  (Croconema)  112 
Onchus  single,  dorsal;  -f ;  cuticle  thin 

Setae  4;  pharynx  small,  closed;  diameter  of  amphid  J  the  width  of  the  head. .  Synonema  110 
Setae  in  2s  and  3s;  phar.  obv.,  open;  diam.  of  amphid  about  i  width  of  head.  Anticyclus  111 


Teeth  two  or  more 


KEY   AND    CHARACTERS  223 

New  Genera 


The  teeth  more  or  less  equal  in  size,  and  usually  mobile 
Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both 

Onchi  or  teeth  have  an  outward  throw;  amphids  circular;  spinneret  present-  -f    Aponchivm    79 
Onchi  or  teeth  have  an  inward  throw 

Amphids  none,  or  so  obscure  as  easily  to  escape  notice;  f-;  teeth  (?)  12 (Synodontium)      65 

Amphids  present 

The  amphids  horse-shoe  shaped,  faint;  striae  fine,  unaltered  laterally;  f-          Synodontium      65 
The  amphids  spiral,  circular,  or  elliptical;  striae  fine,  plain 

Shape  of  amphids  spiral;  winged;  spinneret  pres.;  naked;  head  expanded. .  (Pycnolaimus)      40 
Shape  of  amphids  round  or  elliptical 
Terminus  hamate;  amphid  minute,  &  the  width  of  the  head;  winged        Chambersiella      64 

Terminus  not  hamate;  amphid  J  the  width  of  the  head;  wingless;  -f (Aponchium)      79 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling 
Onchi  or  teeth  have  an  outward  throw;  amphids  present;  spinneret  present 
Form  of  amphids  symmetrical  to  one  line  only;  striae  fine,  plain;  pharynx  bulbous 

Ovaries  two,  'f;  onchi  3,  duplex;  cephalic  setae  6  plus  6;  head  not  set  off Ironella      63 

Ovary  single,  f ' ;  lip-region  set  off;  lips  6,  bipapillate;  spinneret  ventral Trissonchulus      78 

Form  of  the  amphids  spiral,  circular,  or  elliptical 

The  amphids  spiral ;  winged ;  '  f '  (or  -f-) ;  lips  bipapillate ;  cephalic  setae  4 Mesonchium      76 

The  amphids  elliptical;  striae  fine,  resolvable,  unaltered  laterally;  setae  4 Apodontium      62 

Onchi  or  teeth  have  an  inward  throw 

Amphids  0  or  unknown ;  onchi  small,  apophysate,  lips  12,  appendiculate Gammanema      74 

Amphids  present;  spinneret  present  (questionable  in  Crystallonema) 
Contour  of  the  amphids  circular 

Wings  many;  3  mandibulate  lips;  setae  in  3  circlets;  cuticle  rough Xyala      72 

Wing  one  or  none;  striae  not  altered  on  the  lateral  fields 

Cephalic  setae  none;  armature  of  three  biting  plates  or  hooks;  wingless  Tripylium      71 

Cephalic  setae  ten 

Armature,  18  duplex  radiating  refractive  ribs;  winged;  -f Monhystrium      69 

Armature,  6  talon-like  or  digitate  labial  elements;  -f (Crystallonema)      67 

Contour  of  the  amphids  spiral;  striae  resolvable 

Winged ;  ovaries  reflexed  or  outstretched ;  cephalic  setae  4 ;  pharynx  cylindroid .  Mesonchium      76 
Wings  absent;  the  3  onchia  enclosed  in  a  bulb 

Onehj  small,  with  heavy  apophyses;,  encl.  in  swelling;  amphid  of  2j-3J  winds. Trogolaimus      75 
Onchi  large,  without  apophyses;  phar.  bulb  spheroidal,  amphid  of  li  winds.  .Synonchium      73 
The  teeth  usually  unequal  in  size,  not  mobile 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling 

Amphids  none,  or  obscure  and  escaping  notice ;  pharynx  with  many  denticles ; '  f ' .  (Thoo'nchus)      91 
Amphids  present 
The  amphids  irregular,  usually  symmetrical  to  one  line;  spinneret  present;  'f 

Form  of  the  amphids  not  linear;  striae  fine,  plain;  pharynx  denticulate ThoSnchus     91 

Form  of  the  amphids  linear;  striae  coarse,  resolvable;  cephalic  setae  10 (Rhips)    118 

The  amphids  spiral,  circular,  or  elliptical 

Form  of  the  amphids  spiral;  striae  coarse,  plain,  unaltered;  spinneret  present 
Pharynx  and  onchi  minute,  obsc.;  lips  not  thin;  setae  scattered ;  amphids  small. Croconema    112 
Pharynx  obv.;  onchi  plate-like,  submedian;  lips  thin;  setae  10;  amphids  large . Gonionchus      97 
Form  of  amphids  circular  or  elliptical;  spinneret  present  (unknown  in  Gonionchus) 
Winged;  amphids  large,  faint;  lips  appendiculate;  striae  coarse,  resolvable.  .Anaxonchium     99 
Wings  none;  cephalic  setae  10;  striae  plain;  lips  thin 
Ovaries  'f;  striae  fine;  phar.  with  many  denticles;  amphids  obscure,  ellip.. .  (ThoSnchus)      91 

Ovary  -f ;  striae  coarse,  contour  cren. ;  onchi  plate-like;  amphids  spiral (Gonionchus)      97 

Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both 

Amphids  none  or  unknown;  pharynx  bulbous;  striae  fine,  resolvable (Bolbolaimus)    100 

Amphids  present 
Form  of  the  amphids  linear;  wingless;  ovaries  reflexed 

Spinneret  present;  'f;  striae  coarse,  resolvable;  cephalic  setae  10 Rhips    118 

Spinneret  absent;  'f ;  striae  fine,  plain;  cephalic  setae  6  plus  4 Myolaimus     60 

Form  of  the  amphids  spiral,  circular,  or  elliptical 

Shape  of  the  amphids  circular;  striae  fine,  unaltered  laterally;  spinneret  present 
Ovaries  reflexed,  'f ;  lips  bipapil.;  setae  4;  submed.  onchi  minute;  striae  plain .  (Polysigma)    106 
Ovaries  outstretched 
Pharynx  with  distinct  spherical  bulb;  striae  resolvable;  setae  6  +  6  +  4 . . Bolbolaimus    100 

Pharyngeal  bulb  a  faint  swelling;  striae  plain;  cephalic  setae  4 (Aponchium)      79 

Shape  of  the  amphids  a  distinct  spiral;  cuticle  wingless;  spinneret  present 

Onchus  spear-like;  lips  minute,  12;  cephalic  setae  6  +  12  +  6;  striae  fine,  plain. Mesodorus    105 
Onchus  very  small,  not  spear-like;  lips  none  or  obscure 

Lips  bipapillate,  papillae  conical;  'f;  amphids  labial;  cephalic  setae  4 Polysigma    106 

Lips  non-papillate 

Setae  in  6  longitudinal  rows ;  amphids  opp.  pharynx,  \  the  width  of  the  head .  A  laimonema    107 
Setae  none;  amphids  not  opposite  the  pharynx,  J  the  width  of  the  head. . . .  Amphispira    103 


Abbreviations  used  in  Key,  not  found  on  p.  341 

abs,  absent 

cutin,  cutinized 

lin,  linear 

sim,  simple 

apophys,  apophysate 

depr,  depressed 

nar,  narrow 

swol,  swollen 

appar,  apparently 
arc,  arcuate 

devel,  developed 
digit,  digitate 

numer,  numerous 
obsc,  obscure 

spin,  spinneret 
term,  terminus 

buc,  buccal 
chamb,  chambered 

dist,  distally 
ea,  each 

obv,  obvious 
pap,  papillae 

thr,  through 
tub,  tubular 

clav,  clavate 

encl,  enclosed 

pres,  present 

uni,  uniform 

col,  colored 
cren,  crenate 

lab,  labial 

prom,  prominent 

unstr,  unstriated 

224  KEY   TO   THE   MALES 


TJRSA  PRESEN:  spcua  two,  equa;  ta     more  or  ess  arcuate-cono;  no  sp 
Accessories  pres.;  no  suppl.;  spicula  li  long  as  anal  body  width,  straightish;  -m 
Accessories  none;  spicula  2CC  as  long  as  anal  body  diameter,  cephalated  by  con 
Supplements  0;  spicula  L-form;  -m;  post,  half  of  tail  cylindroid;  terminus  rou 


New  Genera 
BTJRSA  PRESENT:  spicula  two,  equal;  tail  more  or  less  arcuate-conoid;  no  spinneret 

-m.  .  Aphele.nchulus      81 

nstriction 

Supplements  0;  spicula  L-form;  -m;  post,  half  of  tail  cylindroid;  terminus  rounded.  lotonchium      82 
Supplements  2()2,1  ;2,  clav.-digit.,  apic.;  ?'m;  spicula  obsc.,  straight;  terminus  blunt.  Myolaimus      60 
BURSA  NONE 

Spiculum  one,  straight,  uncephalated,  'm;  spinneret  none;  tail  acute 

Accessories  pres.;  1;()1;1,  simple  (postanals,  single);  spicula  2ee  anal  body  width.  .Cephalobellus      23 
Accessories  none;  supplements  present,  papilloid;  found  in  insects 

Supplements  2();2;  spiculum  one-fourth  as  long  as  anal  body  diameter;  tail  conoid.  Blattophila      55 
Supplements  simple;  spiculum  twice  as  long  as  anal  body  diameter 

Anus  90;  1(),1;1;  small  access.  (?);  tail  hemispheroid,  then  conoid;  terminus  conical.  Protrellus      38 
Anus  80;  accessories  (?)  ;  tail  conical,  its  terminus  pointed  ......................  Cephalobellus      23 

Spicula  two,  equal,  more  or  less  arcuate  (exc.  Cophonchus,  Synonchium,  lotalaimus,  Ironella,  Bol- 

binium,  Myctolaimus?) 

The  spicula  jointed,  long,  not  distinctly  cephalated,  of  uniform  width;  spinneret  present 
Supplements  none;  -m-;  terminus  clavate;  spinneret  armed;  accessories  apophysate  ----  Xinema      47 

Supplements  25,  vent.,  preanal,  simple,  rather  faint;  -m:  tail  conoid;  aces,  not  &pophys..Rhips    118 
The  spicula  not  jointed;  tail  conoid  or  subconoid  (cylindroid  posteriorly  in  Amicyathus,  Anti- 
cyclus,  Cophonchus,  Cyartonema,  Gonionchus,  Daptonema,  Halanonchus,  Ironella,  Anaxon- 
chium,  Monhystrium,  Schistodera,  Pepsonema,  Myctolaimus,  Rhabdocoma,  Bolbella,  Thoonchus, 
Trilepta,  Mesonchium,  Cytolaimium,  Tripyliu'm,  Zygonemella,  Synodontium  and  (?)  Xennella) 
Accessories  to  the  spicula  none,  or  very  faint 
Supplements  present;  spinneret  absent,  except  in  Synonchium 

Supps.  dorylaimoid;  spic.  cephalated  by  expans.,  width  unif.;  -m-;  term,  rounded  .  Beryllium      84 
Supps.  all  ventral;  spicula  about  H-2ce  as  long  as  anal  body  diameter,  uncephalated 
Position  of  supps.  not  preanal  only;  4  preanal,  simple;  1  postanal,  not  simple;  =m?  .  Colpurella      39 
Position  of  supplements  preanal  only;  supplements  simple 

No.  of  supps.  4;  spicula  not  of  uniform  width;  ?  =  m;  tail  rather  irreg.  conoid  .Colpurella      39 
No.  of  supps.  2;  spicula  straight,  width  rather  unif.;  tail  conoid-hemispherical  Synonchium      73 
Supplements  none  or  exceedingly  faint 

Spicula  slightly  cephalated  by  expansion,  unif.;  tail  conoid,  then  cylindroid;  -m-.  Zygonemella     26 
Spicula  not  cephalated 

Width  of  the  spicula  not  uniform;  spinneret  absent  (?) 

Spicula  straight;  about  \  as  long  as  anal  body  diam.;  tail  short,  bluntly  conoid.  Bolbinium      16 
Spicula  arcuate;  -m  ;  tail  conoid,  then  cylindroid,  its  term,  rounded,  J  as  wide  as  base  .  Trilepta      92 
Width  of  the  spicula  more  or  less  uniform;  spinneret  present,  except  in  Triplonchium 
Spicula  straight;  tail  conoid-hemispherical;  term,  broad;  spinneret  a  pore.  .  (Synonchium)      73 
Spicula  arcuate 
Spinneret  absent 
Spicula  very  strongly  arcuate;  bursa  (?)  ;  terminus  broad,  rounded;  -m  ----  (Triplonchium)      80 

Spicula  not  very  strongly  arcuate;  no  bursa;  terminus  not  broad  ............  (Rhabdocoma)      32 

Spinneret  present;  spicula  not  strongly  arcuate;  no  bursa 

Anus  85;  tail  conoid,  then  cylindroid;  width  over  5%;  spic.  only  slightly  arcu..  Zygonemella      26 
Anus  97;  term,  broad,  rounded;  width  about  1%;  -m;  single  questionable  supp.  .  Nemanema        2 
Accessories  to  the  spicula  present 

Supplementary  organs  present  near  the  anus  (for  alternative  see  middle  opposite  page) 
The  supplements  not  all  ventral;  spicula  1J-1|  as  long  as  anal  body  diameter 
Position,  preanal;  not  simp.;  2  rows  38  ea.;  non-unif.  spic.  uncephalated;  -m  ......  Polysigma    106 

Position,  not  preanal  only;  no  spinneret  (except  in  Catanema  and  (?)  Cytolaimium) 
Form  of  supplements  simple;  -m-;  spicula  uncephalated,  width  rather  uniform 
Supplements  papilloid,  5  preanal,  4  postanal  in  pairs  ..........................  Isolaimium      41 

Supplements  discoid,  11  pre-,5  postanal  pairs;  spic.  1J  long  as  anal  body  diam..  Cytolaimium      31 
Form  of  the  supplements  not  simple 

Spicula  not  cephalated  ;  16  pairs  of  supplements;  terminus  barely  swollen  ;  -m-  .  Cytolaimium      31 
Spicula  cephalated 

Cephalated  by  constriction,  straight?,  width  not  uniform;  9  pairs  papillae;  '  m.  Myctolaimus      61 
Cephalated  by  expansion:  width  of  spicula  rather  uniform 

Arrangement  of  papilloid  supps.  1,1,1,1,1.1,1(1),2,1,1;3,;  'm;  term,  hooked  .  CJiamb»rsi(lln      64 
Arrangement  of  tub.  supps.  postanal,  submed.,  about  7  prs.;-m;  term,  straight  Catanema      56 
The  supplements  all  ventral;  spinneret  present  (exc.  Anticyathus,  (?)  Anticyclus,  Neurella) 
Position,  preanal  17,  postanal  few,  simple;  spicula  uncephalated,  tapering  (?);  -m-.Anticych>s    111 
Position  of  supplements  preanal  only 

Structure  of  supplements  not  simple  (for  alternative  see  page  225) 
Proximal  ends  of  the  spicula  not  cephalated 

Width  not  uniform,  length  1?  anal  body  diam.;  37  "  campanulate  "  supps.;  -m.  Alaimonema    107 
Width  of  the  spicula  more  or  less  uniform 

No.  of  supplements  1;  spicula  2|  times  as  long  as  anal  body  diam.  .straight;  =m  (Ironella)      63 
No.  of  supplements  4  or  more;  terminus  more  or  less  blunt 

Apophysis  present;  spicula  3ce  as  long  as  anal  body  width;  supps.  12;  'm.  .  Aponchium      79 
Apophysis  none;  spicula  long  as  anal  body  diam.  ;  ace.  prom.  ;  supps.  4  ;  -m  .  Acanthonchus    101 
Proximal  ends  of  the  spicula  cephalated 

Spicula  cephalated  by  constriction,  twice  as  long  as  anal  body  diameter 

Supplements  2,  not  simple;  spicula  rather  uniform,  their  cephalation  faint;  -m-  .  Bolbella      90 
Supplements  6,  mammiform;  width  of  spicula  not  uniform;  -m(?)  ..........  Xanthodora      98 

Spicula  cephalated  by  expansion  or  contraction;  width  of  spicula  rather  uniform 
Cephalated  by  contraction,  strongly  arcuate,  as  long  as  anal  body  diam.  ;  -m  .  (Stilbonema)      19 
Cephalated  by  expansion 

Supplement  one,  tubular;  spicula  nearly  straight;  tail  conoid,  then  cylindroid 
Length  of  spicula  5-6  anal  body  diameters;  -m-;  spinneret  bluntly  conoid.  .  .Cophonchvs    108 
Length  of  spicula  2j  anal  body  diameters;  =m;  supplement  bent  toward  anus.  .Ironella      63 


KEY   TO   THE   MALES  225 

New  Genera 

Supplements  numerous,  8-21 

Length  of  spic.  2ce  anal  body  width;  proximae  hooked;  supps.  21,  flat;  -m-.  Trogolaimus      75 
Length  of  spicula  1-1  i  times  as  great  as  the  anal  body  diameter 

No.  of  protrusile(?)  tub.  supps.  8;  ace.  |  as  long  as  spic.,  bends  away;  -m' .  Antomicron      17 
No.  of  faint,  non-tubular  supps.  16;  ace.  parallel,  J  as  long  as  spicula ;-a\-.Gammanema      74 
Structure  of  supplements  simple 
Proximal  ends  of  the  spicula  not  cephalated 
Width  of  spicula  not  uniform 

No.  of  supplements  one,  flat,  faint;  accessories,  simple,  faint;  =m(?) Neurella      25 

No.  of  supplements  17,  low,  papilloid ;  spinneret  (?);  term,  slightly  swollen.  .(Anticyclus)    111 
Width  of  spicula  more  or  less  uniform 

No.  of  supplements  two,  obscure;  accessories  stout;  term,  convex-conoid,  acute.  .Nudora    113 
No.  of  supplements  15-20;  terminus  not  acute 

Length  of  the  spicula  twice  as  great  as  the  anal  body  diameter;  'm Anaxonchium      99 

Length  of  the  spicula  as  great  as  the  anal  body  diameter;  -m- Halanonchus     51 

Proximal  ends  of  the  spicula  cephalated 

Cephalated  by  constriction,  about  1J  as  long  as  anal  body  diameter;  supplements  6-40 
Width  of  spicula  rather  uniform;  accessories  2,  apophysate;  -m;  term,  blunt. Margcnema      27 
Width  of  spicula  not  uniform 
Accessory  with  apophysis;  -m-;  tail  fine,  cylindroid;  term,  blunt;  no  spin.  (Anticyathus)      24 

Accessories  without  apophysis,  two;  terminus  convex-conoid,  acute Bolbolaimus    100 

Cephalated  by  expansion  or  contraction 
The  cephalatiqn  is  by  expansion 

Width  not  unif.;  supps.  5-6;  -m-;  accessory  with  apophysis;  spinneret  armed . Halinema      52 
Width  of  spicula  uniform  or  apparently  so 

No.  of  supplements  3;  spicula  15  times  as  long  as  anal  body  diameter;  -m  Rhynchonema      43 
No.  of  supplements  25-65;  spicula  1  or  1J  times  as  long  as  anal  body  diameter 
Apophysis  to  the  accessory  present;  -m-;  spinneret  armed,  3-lobed ....  Synvdcnlium      65 

Apophysis  to  the  accessory  none;  -m;  spinneret  unarmed;  anus  raised Mesodorus    105 

The  cephalation  is  by  contraction;  width  of  the  spicula  not  uniform 
No.  of  the  supplements  1-3 

Spicula  lj  times  as  long  as  the  anal  body  diam;  supps.  mere  innervations Ypsilon     96 

Spicula  twice  as  long  as  the  anal  body  diam;  single  elevated  supp;  -m- Thoonchus      91 

No.  of  the  supplements  4  or' more;  spicula  tapering  both  ways 

Spicula  long  as  anal  body  diam;  accessory  apophysate;  -m-;  no  spinneret..  Anticyathus      24 
Spicula  twice  as  long  as  anal  body  diameter;  accessory  not  apophysate 
Anus  98;  width  1.6%;  -m-;  single  elevated  supp;  2  dozen  innervations. . .  .Thodncfius      91 
Anus  92;  width  3.8%;  -m;  series  of  ventral  supps.;  nar.  spinneret-tube.  .Micromicron    104 
Supp.  organs  0;  spinneret  pres.  (exc.  Crystallonema,  Triplonchium,  lotalaimus,  Cephalobium) 
Inner  ends  of  the  spicula  not  cephalated,  or  not  obviously  so 
Width  of  spicula  not  uniform;  spicula  1-li  times  as  long  as  anal  body  diameter 
Form  of  spic.  subarcuate;  spin,  midway  on  tail,  ventral;  'm-;  term,  rounded  .  ..Trissonchulus      78 
Form  of  spicula  arcuate 

Apophysis  to  accessory  extends  backward;  spicula  1-1 J  long  as  anal  body  diameter 
Spinneret  none;  term,  unarmed;  -m;  spic.  strongly  arcuate;  no  caudal  setae. Crystallonema      67 
Spinneret  present;  term,  faintly  armed;  -m-;  minute,  inconspic.  caudal  setae . Linhomoella      35 
Appphysis  to  accessory  none 

Wings  to  the  cuticle  present,  also  in  anal  region;  spicula  strongly  arcuate Xennella       6 

Wings  to  the  cuticle  none 

Accessory  inconspicuous;  spinneret  (?);  terminus  j  as  wide  as  base  of  tail;  -m.  .Trilepta      92 
Accessories  parallel,  then  bent  away ;  spin,  armed;  term.  J  wide  as  base;  -m. . . .  (Stilbonema)      19 
Width  of  the  spicula  more  or  less  uniform 

Length  of  spicula  2-3  times  as  great  as  anal  body  diameter;  ace.  with  backward  apophysis 
Form  of  spic.  straight  thr.  middle,  arc.  dist.;  3ce  long  as  anal  body  diam.;  -m-.Mesonchium      76 
Form  of  spicula  arcuate  throughout,  about  twice  as  long  as  anal  body  diam. ;  -m .  Cyartonema      18 
Length  of  the  spicula  1-J-1J  times  as  great  as  the  anal  body  diameter 

Accessories  massive;  supps.  2,  obscure;  term,  convex-conoid;  spin,  large,  acute (Nudora)    113 

Accessories  obscure;  no  suppelments;  terminus  blunt 

Form  of  spic.  very  strongly  arcuate;  rudiment,  bursa  pres.;  no  spinneret ;-m  Triplonchium      8 
Form  of  spic.  not  strongly  arcuate,  rather  stout,  blunt;  no  bursa;  spinneret?. Rhabdocoma      32 
Inner  ends  of  spicula  cephalated;  spinneret  present,  except  in  lotalaimus  and  Cephalobium 
Proximal  ends  of  the  spicula  cephalated  by  constriction,  width  not  uniform 
Length  of  the  spicula  twice  or  nearly  twice  or  great  as  anal  body  diameter 
Apophysis  to  ace.  tapering;  tail  not  striated;  spinneret  swan's-head  form,  unarmed .  Nemella      10 
Apophysis  to  ace.  none;  tail  striated;  spin,  elongated-conoid,  armed;  -m.  .Ptycholaimellus    116 
Length  of  the  spicula  1J  times  as  great  as  anal  body  diameter 

Form  of  spicula  straightish;  'm;  term,  blunt,  nearly  J  as  wide  as  base;  no  spin.. lotalaimus      15 
Form  of  spicula  arcuate 

Spinneret  none;  -m;  terminus  acute,  unarmed;  width  of  the  body  3% Cephalobium      54 

Spinneret  present 

Spinneret  tub.;  anus  90;  width  of  body  more  than  3%;  term,  unarmed;  -m.  .Monhystrium      69 
Spinneret  simple;  width  of  body  less  than  1% 

Termjnus  swollen ;  accessories  2 ;  anus  95% ;  caudal  setae  faint,  anal  only ;  -m-? .  Schistodera 
Terminus  not  swol.;  ace.  1,  more  massive  dist.;  anus  97.5;  setae  not  anal  only  Laxonema      20 
Proximal  ends  of  the  spicula  cephalated  by  contraction  or  expansion 
Ends  of  the  spicula  cephalated  by  contraction  (for  alternative  see  top  next  page) 
Width  of  the  spicula  uniform ;  spicula  about  as  long  as  anal  body  diameter 
Anus  98;  -m ;  cephalum  short,  faint;  anal  annules  strongly  modified  ventrally.  .Stilbonema      1 

Anus  94;  -m-;  cephalum  elongated,  contraction  distinct Cinctonema      22 

Width  of  the  spicula  not  uniform 

Length  of  the  spicula  twice  the  anal  body  diameter;  -m-;  terminus  rounded. .  (Thoonchus)      9 
Length  of  the  spicula  equaling  anal  body  diameter 

Cuticle  =  |  radius;  annules  \  anal  body  width,  elements  not  tile-shaped.   Achnonema    117 
Cuticle  less  than  }  radius;  annules  }  anal  body  width,  elements  tile-shaped    Ceramonema     48 


226  KEY   TO   THE   MALES 

Ends  of  the  spicula  cephalated  by  expansion  ffew  Genera 

Width  of  the  spicula  not  uniform 

Length  of  spic.  equal  to  2  anal  body  diams.;  -m-;  tail  finally  oylindroid;  spin.?  .Gonionchus     97 
Length  of  spioula  equal  to  IJ-li  anal  body  diameters 

Apophysis  to  ace.  backward-pointing;  spic.  1J  long  as  anal  body  diam;  -m-.Coinonema     42 
Apophysis  to  accessory  none 

Accessories  2,  bending  away  from  the  spicula;  spinneret  unarmed;  -m Zalonema     57 

Accessory  1,  parallel  to  the  spicula;  spinneret  armed;  -m-(?) Leptonemella     21 

Width  of  the  spicula  more  or  less  uniform 
Length  of  the  spicula  about  1-1$  times  the  anal  body  diameter 
Form  of  the  spicula  only  slightly  arcuate 

Tail  diminished  to  a  narrow  terminus;  -m-;  accessory  i  as  long  as  spicula.  .Zygonemella     26 
Tail  not  diminished  t9  a  narrow  terminus;  accessory  j  long  as  spicula,  sigmoid . Rhinema    114 
Form  of  the  spicula  distinctly  arcuate,  or  bent 
Apophysis  to  the  accessory  present 

Term,  swol.;  spin,  rounded,  unarmed;  -m;  proximal  3rd  of  spic.  straight. Campylaimus  5 
Terminus  apiculate;  spinneret  acute,  armed;  -m-;  ace.  soon  bends  away. .  (Coinonema)  42 
Apophysis  to  the  accessory  none 

Spicula  not  L-shaped;  ace.  slender,  parallel,  \  &s  long  as  the  spicula;  ^m.Alaimella  1 
Spicula  L-shaped;  striae  resolvable  into  elements 

Accessory  f  as  long  as  dark-colored  spicula;  tail  without  wings Omicronema     50 

Accessory  \  as  long  as  spicula;  tail  with  wings Xyala     72 

Length  of  the  spicula  about  twice  to  thrice  that  of  anal  body  diameter  (Tripylium,  1 f) 
Form  of  spic.  normally  straightish,  arcuate  in  strong  ace. ;  spinneret  blunt.  (LeptoQastrella)     28 
Form  of  the  spicula  arcuate 
Apophysis  to  the  accessory  present 

The  accessory  surrounds  posterior  J  of  hamate  spicula;  -m;  caudal  setae  few.Iotadorus  115 
Theaccessory  parallel  to  narrow  spicula;  -m-;  caudal  setae  many,  in  4  TovfS.Pepsonema  77 
Apophysis  to  the  accessory  none 

Accessory  tub.,  strongly  developed,  enveloping  spic.;  numer.  setae;  -m.LeptoQastrella  28 
Accessory  not  tubular 

Accessory  bends  away  from  spic.,  J  long  as  spic.;  -m;  term,  blunt,  armed.  Apodontium  62 
Accessory  parallel  to  the  spicula 

Anus  85;  ace.  surrounds  laterally  bent,  dark-col,  spic.;  -m-;  spin,  armed. Daptonema  66 
Anus  more  than  90;  spicula  not  laterally  bent,  not  dark-colored;  spinneret  unarmed 

Spinneret  blunt,  tubular;  anus  93;  -m;  accessory  f  as  long  as  spicula Tripylium     71 

Spinneret  conical,  plain;  anus  96;  -m;  accessory  parallel  to  distal  halves. Psevdonchus     58 

THE   NEMA   FORMULA 

Nema  dimensions  sometimes  vary  perceptibly  with  varying  technique. 

As  a  rule,  information  conveyed  in  the  keys,  formulae  and  illustra- 
tions is  not  repeated  elsewhere.  Following  other  authors,  the  measure- 
ments for  the  ovaries  are  given  separately  instead  of  in  the  form  of  a 
single  measurement  as  formerly.  Furthermore,  the  oblique  stroke  indi- 
cating the  presence  and  position  of  the  excretory  pore  is  here,  in  No. 
IX,  placed  below  the  formula  line,  the  assumption  being  that  the  for- 
mula shows  the  nema  ventral  side  down.  The  general  form  of  the  spic- 
ula and  accessories  is  shown  in  the  formula  for  the  male,  as  is  also  the 
presence,  number  and  position  of  the  supplements, — indicated  by  small 
suffixes  before  and  after  the  anal  measurement  figure.  The  spicula  dia- 
grams are  of  three  different  degrees  of  curvature,  indicating  nearly 
straight,  arcuate  and  strongly  arcuate  spicula.  The  nature  of  the  prox- 
imal ends  of  the  spicula  is  indicated,  i.  e.  whether  cephalated,  and  if 
cephalated,  whether  by  contraction,  constriction  or  expansion.  Also, 
if  it  exists,  the  presence  of  an  apophysis  to  the  gubernaculum  is  indi- 
cated. The  short,  horizontal  marks  indicating  the  wings  and  the  pres- 
ence and  relative  diameter  of  the  oesophageal  swellings  are  only  dotted 
when  these  features  are  not  of  a  pronounced  nature.  The  mark  indi- 
cating the  presence  of  a  spinneret  is  either  plain  or  so  conventional- 
ized as  to  indicate  that  the  spinneret  is  supplied  with  setae.  The 
absence  of  any  particular  mark  in  the  formula  is  practically  always 
to  be  taken  as  indicating  that  the  particular  feature  in  question  is 
non-existent.  Doubt  is  expressed  by  a  question  mark.  The  reason 


BURSAL   FORMULA   FOR   NEMAS 


227 


to  the  millimeter 

text  term 

formula  line 

100  dom 
250± 

Very  coarse 
Coarse 



750  ± 
1000  ± 

Rather  fine 
Fine 

2000  ±       to 

None 

for  calling  attention  to  these  special  marks  is  that  until  one  becomes 
accustomed  to  them  they  may  appear  rather  insignificant.  Once  rec- 
ognized, they  may  save  the  reader  considerable  time  and  trouble. 

The  adjacent  table  shows  the  various  formula  lines  by  which  the 
number  of  striae  per  millimeter  is  indicated.  See  also  pages  6  and  7, 
where  the  various  signs  used  in  the  formula  are  explained  in  full. 
In  this  number,  the  presence  of  a  bursa 
is  indicated  by  a  curved  stroke  under  the 
transverse  anal  measurement  figure,  and 
the  number  of  bursal  ribs  in  front  of  and 
behind  the  anus  is  indicated  by  suffixes 
in  front  of  and  behind  the  anal  measure- 
ment figure.  Furthermore,  as  already 
noted,  the  form  of  the  spicula  and  gubernacula  is  indicated  by  conven- 
tionalized sketches  appropriately  placed.  See,  for  instance,  page  279. 

BURSAL   FORMULA   FOR  NEMAS 

In  the  following  rather  arbitrary  designations,  which  are  expressed  in 
a  written  formula,  only  the  papillae  and  ribs  on  one  side  of  the  bursa 
are  considered.  They  are  designated  according  to  their  proximity  to 
each  other  and  not  according  to  their  anatomical  and  physiological 
characters.  They  are  regarded  as  either  anal,  pre-anal,  or  post-anal, 
according  as  they  are  opposite  to,  in  front  of,  or  behind  the  anus.  In 
the  graphical  bursal  formula,  the  anus  is  rep- 
resented by  a  pair  of  parenthesis  marks;  all 
papillae  opposite  the  anus  are  indicated  in 
the  parenthesis,  the  pre-anal  papillae  are 
indicated  in  front  of  the  parenthesis,  and  the 
post-anal  papillae  after  the  parenthesis. 
The  papillae  and  ribs  are  considered  as  a 
single  longitudinal  series,  and  each  group  is 
indicated  by  a  digit  representing  the  number 
of  ribs  or  papillae  in  the  group.  The  longitudinal  spaces  separating 
the  groups  of  papillae  and  ribs  are  indicated  by  commas  and  semicolons, 
the  comma  representing  a  short  space,  the  semicolon  a  longer  space.  In 
some  cases  before  and  after  the  parenthesis,  the  punctuation  mark  may 
be  omitted,  thus  indicating  that  the  ribs  or  papillae  are  even  nearer  to 
the  anus  than  in  those  cases  where  the  separation  is  indicated  by  a 
comma  or  semicolon.  A  blank  space  in  the  type  after  the  comma,  or 
after  the  semicolon,  indicates  a  longer  space  than  is  indicated  by  the 
comma  or  semicolon  alone.  By  such  simple  means  it  is  possible  to  indi- 
cate with  considerable  accuracy  the  grouping  and  latitude  of  these  vari- 
ous organs  and  groups  of  organs.  A  glance  at  the  above  illustration, 
Fig.  0,  and  formula  immediately  underneath  will  make  the  matter  clear. 


I;   (2), 


228  "UNLESS  OTHERWISE  INDICATED" 

GENERAL — Unless  otherwise  indicated, — 

1.  The  species  described  under  a  generic  name  is  to  be  regarded  as  the  type 
species  of  the  genus;  where  more  than  one  species  is  described,  the  type 
species  is  specifically  designated. 

2.  The  text  terms  and  formulae  apply  to  the  nemas  as  viewed  in  profile.     Ref- 
erences to  stain  are  restricted  to  acid  carmine. 

3.  The  cuticle  is  colorless. 

4.  The  cuticle  is  striated, — sometimes,  however,  so  finely  striated  as  to  be 
resolvable  only  with  the  highest  powers  of  the  microscope  used  skillfully 
under  favorable  conditions.     The  division  line  of  the  formula  is  used  to 
indicate  approximately  the  number  of  striae  per  millimeter.     (See page  227.) 

5.  The  striae  are  approximately  uniform  in  width  throughout  the  length  of 
the  body  except  toward  the  extremities. 

6.  The  contour  is  plain. 

7.  The  striae  are  not  resolvable  into  secondary  elements.     The  presence  of 
secondary  elements  is  indicated  in  the  formula.     (See  page  7.) 

8.  The  longitudinal  striations  are  due  to  the  attachments  of  the  musculature. 

9.  There  are  no  obvious  series  of  pores  in  the  cuticle. 

10.  There  are  no  eye-spots. 

11.  There  are  no  definite  valves  in  the  oesophageal  bulbs. 

12.  The  lining  of  the  oesophagus  is  a  distinct,  but  not  conspicuous,  feature, 
practically  throughout  its  length. 

13.  The  intestine  is  set  off  from  the  oesophagus  by  a  distinct  constriction. 

14.  The  arrangement  of  the  granules  in  the  cells  of  the  intestine  is  not  such 
as  to  give  rise  to  a  tessellated  effect. 

15.  There  is  no  pre-rectum. 

16.  The  rectum  extends  inward  and  forward  at  an  angle  of  about  thirty  to  forty 
degrees. 

17.  The  tail,  at  least  that  of  the  female,  is  straight,  or  nearly  so. 

18.  The  somatic,  as  well  as  the  posterior  cervical,  setae,  are  perpendicular  to 
the  cuticle,  or  nearly  so. 

19.  The  renette  cell  lies  behind  the  base  of  the  neck. 

20.  The  nerve-ring  surrounds  the  oesophagus  rather  squarely. 

21.  Absence  of  the  formula  for  either  sex  indicates  that  that  sex  is  unknown 
at  the  present  time. 

FEMALE — -Unless  otherwise  indicated, — 

22.  The  vagina  is  understood  to  lead  inward  at  right  angles  to  the  ventral 
surface. 

23.  The  uterus  is  more  or  less  straight. 

24.  The  eggs  are  thin-shelled  and  smooth,  and  are  deposited  before  segmenta- 
tion begins. 

MALE — Unless  otherwise  indicated,— 

25.  There  is  no  bursa. 

26.  The  tail  of  the  male  is  similar  to  that  of  the  female  in  form. 

27.  The  spicula  are  two  in  number,  equal  in  size,  and  appear  moderately  arcu- 
ate when  viewed  in  profile,  and  are  simple,  i.e.,  without  obvious  extra 
component  longitudinal  stiffening  elements. 

28.  The  accessory  piece  (or  pieces),  gubernaculum,  lies  more  or  less  parallel 
to  the  spicula,  and  has  no  inward  or  backward-pointing  apophysis. 


NEW    MORPHOLOGICAL   AND    PHYSIOLOGICAL   DATA  229 

New  Data 

Apart  from  indicating  that  the  nema  phylum  can  be  divided  into  valid,  nat- 
ural orders  on  the  basis  of  the  structure  of  the  mouth  parts  and  related  organs, 
this  article  records  numerous  additions  to  our  knowledge  of  the  morphology  of 
nemas.  Facts  announced  in  a  sentence  or  two,  or  through  the  medium  of  illus- 
trations, might  perhaps  have  been  advantageously  made  the  subject  of  separate 
papers.  Among  these  additions  to  our  knowledge,  the  following  may  be 
mentioned: 

1.  In  a  miscellaneous  lot  of  over  one  hundred  new  genera  of  nemas,  thirty  per 
cent  prove  to  have  jointed  setae.     Probably  a  much  larger  percentage  have 
jointed  setae.     Among  the  nemas  having  setae,  jointed  setae  are  probably 
the  rule  rather  than  the  exception. 

2.  The  distal  ends  of  the  cephalic  setae  sometimes  exhibit  considerable  com- 
plexity, indicating  that  they  are  specially  developed  sense  prgans;  e.g.,  in 
Linhomoella  and  Crystallonema. 

3.  Additional  evidence  that  bilateral  mouth-parts  arise  by  elimination  of  dorsal 
elements  exists  in  Pseudonchus. 

4.  There  is  a  large  group  of  nemas  with  six  well-developed  onchia  having  an 
outward  stroke,  adapted  for  digging;  e.g.,  Apodontium  and  relatives. 

5.  More  than  ever,  it  is  clear  that  amphids  are  practically  universal  among  the 
free-living  nemas.     They  may  be  small  and  difficult  to  see;  as  in  Stilbonema 
and  Laxonema.     In  the  p_ast,  they  have  been  sometimes  overlooked.     Some 
Triplonchs  possess  amphids;  e.g.,  Onchium,  Triplonchium. 

6.  All  amphids  have  backward  connections, — often,  perhaps  always,  tubular  and 
containing  coagulable  substance.     Of  unusual  interest  are  the  huge  glands  of 
lonema. 

7.  Lateral  series  of  organs  occur  in  so  many  of  the  genera  described,  as  to  lend 
additional  weight  to  the  opinion  that  such  series  are  a  normal  element  of  the 
nema  structure. 

8.  There  is  much  additional  evidence  of  differentiation  of  form  and  structure 
among  the  various  cells  of  the  intestine. 

9.  The  presence  of  oesophageal  glands  is  established  for  Axonchium  and  its  rela- 
tives,  (Dorylaimus,  etc.)     They  occur  in  the  posterior  enlargement  of  the 
oesophagus,  one  emptying  into  the  lumen  dorsally  in  its  anterior  part,  and 
often  two  others  emptying  into  the  lumen  farther  back. 

10.  Non-terminal  spinnerets  and  mouth  openings  seem  practically  always  ven- 
tral; e.g.,  Trissonchulus,  Campylaimus. 

11.  A  large  unicellular  gland  is  connected  with  each  supplement  of  the  males  of 
Bolbella  and  Eurystoma. 

12.  The  presence  of  pairs  of  cloacal  glands  in  the  male,  first  observed  by  de  Man 
in  Euchromadora,  is  established  for  many  other  genera. 

13.  Cytolaimian  transition-forms  exist  between  the  parasitic  and  free-living 
nemas;  e.g.,  Monhystrium. 

14.  The  existence  of  double-jointed  spicula  is  established  for  Rhips  and  Xinema. 

15.  Nemas  are  disclosed  in  which  the  sperm  cells  are  of  extraordinary  size;  such 
species  may  prove  useful  in  studies  in  genetics. 

16.  Rhynchonemas  are  distributed  in  various  oceans.     They  are  free-living  nemas 
with  beak-like  heads,  but  otherwise  normal  in  form.     Presumably,  this  beak 
serves  to  extract  food  from  receptacles  the  entrances  to  which  are  narrow. 

17.  There  is  a  marked  absence  of  syngonism  in  marine  forms. 

18.  The  existence  is  demonstrated  of  special  spermatheca,  in  the  form  of  special 
separate  branches  of  the  female  sexual  organs. 


230  ORDER   LITINIA 

I.     Order  Litinia 

.4       lj.4        28.          '-61  88. 

1.  Litotes  minuta  n.  sp.    -7      "      *•          5-i       3.2     •    ~  Cuticle  thin,   naked. 
The  mouth  opening  is  almost  imperceptibly  depressed.     The  conoid  neck  carries 
a  conoid  oesophagus.     The  presence  of  amphids  is  indicated  by  slight,  narrow 
external  markings  of  a  very  faint  character.     In  the  region  of  the  nerve-ring  the 
oesophagus  is  three-fifths  as  wide  as  the  corresponding  portion  of  the  neck,  while 
finally  it  is  five-sixths  as  wide  as  the  base  of  the  neck;  its  lining  is  indistinct, 
its  musculature   fine   and   colorless.    No   oesophageal   glands.    The   intestine 
becomes  at  once  three-fourths  as  wide  as  the  body,  is  thin-walled,  and  but  few 
of  its  cells  are  required  to  complete  its  girth.    The  intestinal  lumen  is  distinct. 

q>hffl(6)  The  distinct  cardiac  collum  is  two-thirds  as  wide  as  the  body. 
[  I  tm  ^ear  i^s  beginning  the  intestine  is  pressed  well  to  one  side  by 
|jf  the  renette  cell,  which  is  more  or  less  ellipsoidal  in  form  and 
oe  -P:  vx  750  granular  in  structure.  It  is  about  as  long  as  the  body  is  wide 
and  about  half  as  wide  as  long,  and  contains  a  very  indistinct  nucleus  of  medium 
size.  There  are  few  granules  in  the  cells  composing  the  intestine.  The  tail 
is  conoid.  Nothing  is  known  concerning  the  longitudinal  fields.  The  nerve- 
ring  is  medium-sized  and  accompanied  by  more  or  less  distinct  groups  of  nerve 
cells.  The  small  indistinct  vulva  is  more  or  less  continuous  with  the  ventral 
surface  of  the  body.  The  rather  weak,  tubular,  non-refractive  vagina  extends 
obliquely  forward  apparently  about  half  way  across  the  body.  The  ellipsoidal 
granular  eggs  are  about  three  times  as  long  as  the  body  is  wide,  and  nearly  one- 
third  as  wide  as  long.  The  broad,  tapering  ovary  contains  six  to  eight  ova 
arranged  single  file. 

Habitat:  Algae,  near  the  lighthouse,  Bahia,  Brazil.  Bears  some  resemblance 
to  Monhystera  and  Oxystoma.  Differs  from  Monhystera  in  having  no  pharynx 
and  no  distinct  amphids;  from  Oxystoma  in  the  form  of  the  amphids  and  the  form 
of  the  female  sexual  organs.  Sublimate  to  balsam.  Fig.  1.* 

2.  Nemanema  simplex  n.  sp.    Head  with  faint  traces  of  papillae  on  the  outer 
part,  indicated  by  refractions  in  the  cuticle.    Possibly  the  exceedingly  minute 

/g\     or  pharynx  contains  an  acute,  forward-pointing  projection  or  tooth,  but 

]    w  all  details  are  so  exceedingly  minute  that  even  under  the  very  highest 

"  *9J        powers  of  the  microscope  they  are  resolvable  with  difficulty.    The 

Jimpn  oesophagus  expands  but  little  until  after  it  passes  through  the  nerve - 

\^  x75o  ring;  thereafter  it  expands  until  near  its  posterior  extremity,  where 

,    I§      74  it  is  two-thirds  as  wide  as  the  base  of  the  neck; 

^       .9,17  i.  n        T8>2-5"  the  posterior  extremity  of  the  oesophagus  stains 

somewhat  differently  from  the  rest.     Cardia  large, 

.2     9.i.-H2i.       "-*       97-^  ._.     conoid,  half  as  wide  as  the  base  of  the  neck.    From 
the  distinct  cardiac  collum  the  intestine  becomes 

at  once  two-thirds  as  wide  as  the  body;  its  cross-section  comprises  about  six 
cells.  The  lateral  fields  are  about  half  as  wide  as  the  body.  When  viewed  dorso- 
ventrally  the  amphids  are  seen  to  be  connected  with  refractive,  cutinized  ducts 
which  lead  inward  and  backward  for  a  short  distance  and  then  become  indefinite. 
Tail  conoid,  its  terminus  three-fifths  as  wide  as  its  base.  The  large,  elongated, 
narrow  caudal  glands  lie  tandem  on  the  ventral  side  in  front  of  the  anus,  the 
foremost  being  removed  from  the  anus  a  distance  three  to  six  times  as  great  as 
the  length  of  the  tail.  Observations  on  the  ventral  gland  and  excretory  pore 

•  Each  figure  is  designated  by  the  number  of  the  genus  it  illustrates.  If  two  species  of  the  genus 
are  illustrated,  the  figures  are  designated  a  and  ft,  respectively. 


NEMANEMA,    TYCNODORA,    SCHISTODERA 


231 


have  not  been  satisfactory,  but  it  appears  as  if  there  is  a  small,  narrow,  elongated 
ventral  gland  a  short  distance  behind  the  cardiac  constriction,  where  the  intes- 
tine lies  a  little  to  one  side.  Each  lateral  field  contains  large  ellipsoidal  cells,— 
too  large  to  be  placed  side  by  side  within  its  limits;  they  are  placed  alternately 
to  one  side  and  then  the  other.  Their  size  is  such  that,  in  the  neck  at  least, 
if  they  were  arranged  single  file  they  would  make  a  continuous  series  a  little 
more  than  half  as  wide  as  the  field  and  about  one-third  as  wide  as  the  body. 
From  the  raised  vulva,  the  vagina  leads  half  way  across  the  body,  where  it  joins 
the  single  uterus,  which  extends  backward.  The  ovary  reaches  about  half  way 
back  to  the  vulva  and  contains  a  score  or  more  of  developing  ova,  which  are 
arranged  for  the  most  part  single  file.  Anterior  branch  rudimentary.  The  elon- 
gated eggs  are  about  four  times  as  long  as  the  body  is  wide  and  about  one-sixth 
as  wide  as  long.  The  tail  of  the  male  is  slightly  more  arcuate  than  that  of  his 
mate.  Opposite  the  proximal  ends  of  the  spiculai,  there  is  a  very  low,  rounded, 
ventral  elevation.  Near  the  ventral  line  in  front  of  the  anus  for  a  distance  two 
to  three  times  as  great  as  the  length  of  the  tail  there  are  a  few  minute  setae, 
about  one-eighth  as  long  as  the  body  is  wide,  and  immediately  behind  the  anus 
there  are  one  or  two  similar  setae;  otherwise  there  are  no  indications  of  special 
papillae  or  setae.  Spicula  about  one  and  one-half  times  as  long  as  the  anal 
body  diameter.  Their  proximal  ends  lie  near  the  dorsal  side  of  the  body. 

Habitat:  Algae  and  marine  sand  at  their  bases,  in  surf,  Island  off  Port  Royal, 
Jamaica.     Sublimate  to  balsam.    Fig.  2,  p.  230. 


3.  Tycnodora  pachydermata  n.  sp.  -36  i-2  i-5  i-s  .84  "  "  Cuticle  thick, 
glassy;  near  the  head  more  nearly  colorless,  sometimes  smoky,  at  any  rate  after 
treatment  with  Flemming's  solution;  near  the  middle  of  the 
body,  occupying  one-sixth  the  radius;  near  the  spinneret 
much  thinner  than  elsewhere;  rather  suddenly  diminishing 
in  thickness  near  the  nerve-ring.  Lining  of  oesophagus  sub- 
distinct;  the  musculature  fine  and  colorless.  There  is  no 
cardia.  The  thin-walled  intestine  is  separated  from  the 
oesophagus  by  a  collum  one-fourth  as  wide  as  the  body.  The 
lumen  of  the  intestine  is  faint.  From  the  depressed  anus  the 
inconspicuous  rectum  extends  inward  a  distance  twice  as 
great  as  the  anal  body  diameter.  Very  few  granules  are  to 
be  seen  in  the  intestinal  cells.  The  contents  of  the  intestine 
are  finely  granular.  The  more  or  less  arcuate  tail  is  first  co- 
noid, then  cylindroid  in  the  posterior  fourth,  where  it  is  about 
one-fourth  as  wide  as  at  the  anus.  The  lateral  fields  are  one- 
half  as  wide  as  the  body.  From  the  inconspicuous  vulva, 
the  cutinized  vagina  extends  one-third  the  way  across  the 
body.  The  somewhat  cylindroid  ovaries  extend  two-fifths 
the  way  back  to  the  vulva  and  carry  twelve  to  twenty  ova 
arranged  more  or  less  single  file. 

Habitat:  "Seagrass,"  shoal,  two  miles  off  Key  West,  Fla.,  U.  S.  A.  Flemming  to 
glycerine  jelly.  Resembles  Halalaimus,  but  the  female  has  two  reflexed  ovaries. 
Fig.  3. 

«  <aM!»"         or 


s/a 


X750 


4.  Schistodera  exilis  n.  sp.  .1 


The  naked  cuticle  is 


extremely  thin.  From  the  mouth  about  one-third  the  way  to  the  anterior  mar- 
gin of  the  lateral  organs,  the  lining  of  the  oesophageal  tube  is  a  little  more  mas- 
sive than  farther  back.  The  amphids  are  interesting  on  account  of  the  presence 


ORDER   LITINIA 


in  the  posterior  portion  of  the  cavity  of  each  of  a  strongly  staining  body,  which 
may  be  assumed  to  be  protoplasmic.  The  bottoms  of  the  amphids  are  strongly 
cutinized.  Oesophagus  conoid,  finally  about  half  as  wide  as  the  base  of  the 
neck;  just  where  it  joins  the  intestine  it  appears  to  expand  suddenly,  although 
Ittl  (4)  or  ^s  exPansi°n  could  hardly  be  called  a  bulb.  It  is  possible  that 

this  expansion  indicates  the  presence  of  glands  about  the  base 
w  of  the  oesophagus.  The  intestine  becomes  at  once  three-fourths 
as  wide  as  the  body  and  in  cross-section  appears  to  present  only 
two  cells.  Little  that  is  definite  is  known  concerning  the  lateral 
fields,  but  it  is  presumed  that  they  are  well-developed.  The 
median  fields  are  rather  distinct.  They  contain  a  series  of  cells, 

I  at  any  rate  in  the  neck;  these  cells  are  about  half  as  long  as  the 
neck  is  wide  and  are  separated  from  each  other  by  distances 
about  twice  as  great  as  their  length.  Tail  of  the  male  at  first 
conoid,  then  cylindroid  in  the  posterior  half,  where  it  is  about 
one-fourth  as  wide  as  at  the  base.  The  spinneret  has  a  very 
minute  pore.  The  caudal  glands  lie  in  front  of  the  anus.  A 
straight  refractive  piece  appears  to  subtend  the  arc  of  the  spicula. 
These  latter  are  barely  cephalated  by  an  almost  imperceptible  expansion  and  a 
previous  constriction.  Immediately  behind  the  anus  there  are  two  or  three 
minute  submedian  setae;  similarly,  close  to  the  anus,  and  in  front,  there  is  a  pair 
of  subventral  setae,— all  seen  with  considerable  difficulty.  The  balance  of  evi- 
dence is  in  favor  of  the  existence  of  two  testes. 

Habitat:  Algae  and  sand  at  their  bases,  in  surf,  Island  off  Port  Royal,  Jamaica. 
Fig.  4. 

5.  Campylaimus  inequalis  n.  sp.    Striae  more  easily  seen  along  the  margin  of 
the  amphids.    Wings  are  indicated  by  the  presence  in  the  lateral  fields  of  two 

1.2  7.5 n.      ^5?:"....??:.  >   7,.  longitudinal  lines 

2.1      3.2""  4.1        4.5       2.9  very   close  together 

and  barely  resolvable 

1.3  9.4 n.        "-*t        *•..  >   6,.  with  high  powers. 

2.  3.* 3-9  •>•*  ""M-z  Like  the  mouth-open- 

ing the  cephalic  setae  are  asymmetrically  placed. 
The  mouth  is  a  simple,  unarmed,  conoid  depression 
on  the  ventral  side  of  the  head  a  little  behind  the 
anterior  extremity.  There  are  no  distinct  lips,  but 
the  anterior  extremity  is  modified  so  as  to  resemble 
a  lip-region;  it  is  set  off  by  a  minute  constriction 
and  presents  a  minute  depression  that  takes  acid- 
carmine  stain  more  strongly  than  do  the  adjacent 

parts.  No  doubt  this  terminal  "cap"  serves  some  distinct  function, — as  tactile 
or  gustatory.  The  conoid  oesophagus  finally  becomes  almost  three-fourths  as 
wide  as  the  base  of  the  neck.  There  does  not  appear  to  be  any  distinct  cardia. 
Around  the  base  of  the  oesophagus  there  is  a  circlet  of  small  cells  which  stain 
in  the  same  manner  as  do  the  cells  of  the  intestine.  This  latter  becomes  at 
once  about  three-fourths  as  wide  as  the  body.  The  lateral  fields  have  not  been 
distinctly  seen.  Nothing  definite  is  known  about  the  renette  and  excretory  pore. 
Tail  conoid  to  the  simple  terminus,  which  is  set  off  by  a  broad,  shallow  con- 
striction. The  caudal  glands  appear  to  be  located  in  front  of  the  anus,  probably 
a  long  distance  in  front  of  it.  In  the  male  the  anus  is  slightly  raised.  Spicula 


CAMPYLAIMUS,    XENNELLA,    ALAIMELLA 


233 


about  one  and  one-half  times  as  long  as  the  anal  body  diameter,  their  proximal 
ends  slightly  cephalated  by  expansion.  They  are  rather  markedly  arcuate  in 
their  distal  two-thirds,  but  nearly  straight  in  the  proximal  third.  There  seems 
to  be  but  a  single  testis. 

Habitat:  Marine  sand  and  mud,  San  Pedro,  California.     Fig.  5. 

.17     11.  _  23.  "-M  92. 

6.  Xennella  cephalata  n.  sp.  -33  V~  !•'  2.3  "^2.2™  °!  "  The  cuticle, 
which  is  of  medium  thickness,  is  traversed  by  six  to  eight  longitudinal  ribs  or 
wings  on  each  side.  There  are  at  least  four  cephalic 
setae,  possibly  six;  otherwise  the  cuticle  seems  to  be 
naked.  The  mitriform  head  is  set  off  by  a  distinct 
constriction.  The  neck  is  cylindroid.  The  some- 
what conoid  oesophagus  is  at  first  one-ninth,  near 
the  nerve-ring  one-fifth,  and  at  last  two-fifths  as 
wide  as  the  corresponding  portion  of  the  neck.  A 
final  obscure  swelling  contains  one  or  more  nuclei, 
which  differ  from  all  other  nuclei  in  the  organ.  The 
lining  of  the  oesophagus  is  indistinct.  The  intestine 
is  separated  from  the  oesophagus  by  a  collum  one- 
fourth  as  wide  as  the  base  of  the  neck,  and  becomes 
at  once  two-thirds  as  wide  as  the  body,  and  in  cross-section  presents  but  few 
cells.  The  anterior  part  of  the  intestine  for  a  distance  about  equal  to  the  length 

of  the  corresponding  body-diameter  has  a 
structure  different  from  the  portion  that  fol- 
lows. The  cells  of  the  intestine  contain 
numerous  very  minute  granules.  The  elon- 
gated granular  renette  cell  is  about  as  long 
as  the  corresponding  body  diameter,  and  lies 
a  little  in  front  of  the  cardia.  It  is  not  re- 
flexed.  Apparently  the  excretory  pore  is 
located  near  the  nerve-ring.  This  latter  is 
oblique,  distinct,  and  broad.  The  spicula 
when  viewed  dorso-ventrally  appear  to  make 
an  angle  of  about  thirty  degrees  with  each 
other.  The  specimens  were  molting. 
Habitat:  "Sea-grass,"  shoal,  two  miles  off  Key  West,  Florida.  Figs.  6a  and  b. 
It  is  believed  only  the  spinneret  was  missing  fiom  the  single  specimen  measured. 

2.       106.        219.  4-5M  866. 

The  actual  measurements  are, ^ 19  ~  18 ^ — ^^-(?)944..iCr... 

la.  Alaimella  cincta  n.  sp.  Cuticle  relatively  thick.  The  secondary  elements 
of  the  striae  are  on  the  limits  of  visibility  and  reach  nearly 
across  the  annule.  There  are  probably  six,  flat,  amalgamated 
lips.  The  conoid  neck  contains  an  oesophagus  which  is  more 
or  less  clavate  at  the  rear  end.  Near  the  mouth  it  is  one-half, 
at  the  nerve-ring  two-fifths,  and  finally  three-fifths,  as  wide  as 
the  corresponding  portion  of  the  neck;  its  lining  is  indistinct. 
There  may  be  a  faint,  conoid  cardia.  Intes-  „ 

tine  at  once  about  three-fourths  as  wide  as  the      i°— __9J.*_:_j fi- 

body,   more   or   less  thin-walled,    and  present- 
ing but  few  cells  in  cross-section.     The  intesti-       iy'iTf r~~n 1~f" 

nal    cells    contain    numerous,    rather    uniform 

granules,  regularly  placed.     From  the  continuous  anus,  the  cutinized  rectum 


234  ORDER   LITINIA 

is  about  twice  as  long  as  the  anal  body  diameter.  Tail  conoid.  The  eggs  are 
two  to  three  times  as  long  as  the  body  is  wide.  The  ova  are  arranged  more  or 
less  in  single  file,  and  the  ovary  extends  two-thirds  the  way  back  to  the  vulva. 
The  proximal  ends  of  the  slender,  somewhat  tapering,  rather  frail,  subacute  spic- 
ula  lie  opposite  the  body  axis.  There  are  two  rather  frail,  simple  accessory  pieces. 
Habitat:  Sand-bar,  Biscayne  Bay,  Florida,  U.  S.  A.  Flemming  to  glycer'ne 
jelly.  Fig.  7a,  p.  233. 

-•°_--^._J>5-il_JJL___j»-_>(?)1.3.. 

b.  Alaimella  truncata  n.  sp.  -6      u      ^5         1.5  ~N\  1.5  This,  the  type  species 

of  Alaimella,  rather  closely  resembles  Alaimella  cincta.  Secondary  markings  of 
the  cuticle  faint,  if  any.  Oesophagus  as  in  cincta,  except  relatively  a  trifle  nar- 
rower. Intestine  as  in  cincta,  but  narrow  and  displaying  only  two  cells  in  cross- 
section,  the  cells  containing  minute  inconspicuous  granules, 
Proximally  the  slender,  uniform,  simple,  frail  and  subacute 
spicula  expand  much  and  suddenly,  to  form  flattish  cephala, 
located  about  opposite  the  body  axis.  There  seem  to  be  two 
simple,  frail,  sub-slender,  more  or  less  arcuate  accessory 
pieces,  which  are  probably  joined  together  at  the  anus.  There 
appear  to  exist  throughout  the  length  of  the  body  an  unusual  x  750  V  t  i  oe 
number  of  nuclei  ventrad  from  the  narrow  intestine,  which  keeps  well  to  the 
dorsal  side.  Both  before  and  behind  the  anus  there  are  some  very  slender  ven- 
trally  submedian  setae  half  as  long  as  the  body  is  wide.  Ejaculatory  duct  about 
one-third  as  wide  as  the  body.  Forward-pointing  testes  two-fifths  as  wide 
as  the  body.  In  the  single  male  examined,  which  appears  to  be  immature,  one 
testis  ended  four  tail-lengths  from  the  anus,  the  other  five  tail-lengths  from  the 
anus.  At  one  tail-length  in  front  of  the  anus  there  occurred  one  or  two  glands 
(?)  with  very  brilliantly  staining  nuclei,  whose  connections  remain  unknown. 

Habitat:  Algae,  near  lighthouse,  Bahia,  Brazil.     Sublimate  to  balsam.     Fig.  7b. 

.8        4.5        9.5  12'"        96. 

8.  Litinium  aequale  n.  sp.  1.3  t-7/  i.s  LS  1.7  '  "  Oesophagus  at  first 
three-sevenths,  near  the  nerve-ring  one-third,  and  finally  three-sevenths,  as  wide 
as  the  corresponding  portion  of  the  neck.  Its  lining  is  indistinct.  There  seems 
tt>f  nt/fi)  i  a-  tot  t/fi}  *°  ke  no  distinct  cardia.  The  intestine,  which 

"  is  separated  from  the  oesophagus  by  a  collum 
three-sevenths  as  wide  as  the  neck,  becomes  at 
once  half  as  wide  as  the  body.  Its  walls  are 
thick  and  its  lumen  faint.  The  granules  con- 
tained in  the  cells  of  the  intestine  are  numerous 
and  more  or  less  uniform.  The  anus  is  more  or 
less  continuous,  the  rectum  inconspicuous.  The 
hemispherical-conoid  tail  tapers  from  the  anus 
to  the  terminus.  There  are  no  caudal  setae. 
X750  The  cau(ial  glands  are  located  in  front  of  the 
anus.  The  lateral  fields  are  about  one-fourth  as  wide  as  the  body.  The  nerve 
ring  is  of  medium  size  and  on  either  side  of  it  are  obscure  nerve  cells.  From  the 
large,  depressed,  but  rather  conspicuous  vulva,  the  vagina  leads  obliquely  back- 
ward a  distance  two-thirds  as  great  as  the  body  diameter.  Judging  from  the  size 
of  the  ovum  just  before  it  leaves  the  ovary,  the  eggs  are  about  one  and  one-half 
times  as  long  as  the  body  is  wide.  In  the  broad,  cylindroid  ovary  are  twenty  to 
forty  ova  arranged  single  file  except  in  the  distal  half,  where  they  are  arranged 
irregularly. 

Habitat:  Sand,  Ocean  Beach,  Miami,  Florida,  U.  S.  A.  Flemming  to  glycerine 
jelly.  Fig.  8. 


IONEMA  235 

.2       5-9       7.W      "'y?''        92. 

9.  lonema  ocellatum  n.   8p.  "•*""'£"" i-"" i's L' >    a"  The   thin  cuticle  is 

naked  except  for  the  cephalic  setae.  There  are  no  traces  of  lips.  The  amphids 
are  very  inconspicuous.  The  neck  is  cylindroid  posteriorly,  and  convex-conoid 
anteriorly,  especially  near  the  head.  The  eye-spots  are  light  brown  in  color, 
and  each  has  a  refractive  element  in  front.  In  the  pigmented  portion  of  each 
eye  there  is  a  more  or  less  central  nucleus  with  a  subsidiary,  small  companion 
object.  The  cylindroid  oesophagus  is  at  first  one-third,  near  the  nerve-ring  one- 
fourth,  and  finally  one-fifth,  as  wide  as  the  corresponding  portion  of  the  body. 
Its  lining  is  indistinct.  There  is  no  cardia.  Owing  to  the  presence  of  large 
somatic  glands,  observation  of  the  junction  of  the  oesophagus  with  the  intestine 
is  difficult.  The  collum  appears  to  be  one-fifth  as  wide  as  the  corresponding 
portion  of  the  body.  The  intestine  is  two-thirds  to  three-fourths  as  wide  as 
the  corresponding  portion  of  the  body,  and  is  thick-walled,  and  has  a  very  faint 
lumen.  The  cells  of  the  intestine,  which  appear  somewhat  as  if  overlapping, 
contain  more  or  less  uniform,  yellowish,  scattered  granules;  they  have  large, 
spherical,  granular  nuclei  with  conspicuous  nucleoli.  The  arcuate,  conoid  tail 
tapers  from  the  anus  to  the  unarmed  convex-conoid  terminus.  The  conoid  spin- 
neret is  simple  in  structure.  The  ellipsoidal  caudal  glands  occur  in  a  loose  tan- 
dem series  in  the  anterior  half  of  the  tail.  There  are  no  caudal  setae.  The  lat- 
eral fields  are  two-fifths  as  wide  as  the  body.  The  granular,  elongated,  pyriform 
renette  is  one  and  one-half  times  as  long  as  the  body  is  wide,  and  one-half  as  wide 
as  long.  It  is  not  reflexed  and  lies  near  the  middle  of  the  body,  a  little  in  front 
of  the  flexure  of  the  front  ovary.  The  nerve-ring  is  of  medium  size  and  is  accom- 
panied by  rather  obscure  nerve  cells.  From  the  small,  elevated,  more  or  less 
inconspicuous  vulva  the  medium-sized  vagina  leads  inward  half  m^ 
way  across  the  body;  it  is  more  or  less  strongly  cutinized.  The  ; 
size,  form  and  covering  of  the  eggs  is  unknown,  but  the  ripe  ova  set  (4)' 
are  about  as  long  as  the  body  is  wide.  The  broad,  cylindroid 
ovaries  extend  five-sixths  the  way  back  to  the  vulva,  and  con-  "moe 
tain  about  twenty  ova,  arranged  single  file  in  the  proximal  half,  ^ 
but  irregularly  in  the  distal  half.  The  duct  of  the  renette  is 
necessarily  very  long  and  is  slender;  there  is  a  distinct,  elon-  oe 
gated  ampulla,  with  a  very  long  and  very  slender  duct  leading 
from  it  to  the  pore.  This  latter  duct  is  about  as  long  as  the 
body  is  wide.  This  genus,  of  which  there  are  several  species,  spn 
is  made  very  remarkable  by  the  possession  of  a  pair  of  relatively 
huge  glands  filling  most  of  the  body  cavity  behind  the  base  of  X75° 
the  neck  and  ending  two  and  one-half  times  as  far  behind  the  neck  as  this  latter 
is  behind  the  head.  The  points  of  exit  of  these  glands  appear  to  be  at  the  head 
end.  Each  gland  has  a  nucleus  near  its  blind  end.  In  the  vicinity  of  the  nerve- 
ring  the  glands  diminish  in  size,  and  half  way  from  this  point  to  the  head  appear 
to  come  to  a  narrow,  rounded  end,  strictly  lateral  in  position,  and  from  thence 
there  appear  to  be  narrow  ducts  leading  toward  the  lip-region  to  pores,  where 
foreign  particles  are  seen  to  cling,  and  which  are  designated  in  the  drawing 
as  amphids.  Near  the  middle  these  glands  are  pressed  to  one  side  by  two  sub- 
dorsal  cells,  apparently  nerve  cells. 

Habitat:  Marine  algae,  Panama.  Hot  sublimate  to  balsam.  This  genus  is  of 
wide  occurrence  in  tropical  oceans;  specimens  from  both  the  East  and  West 
Indies  are  known  to  the  writer.  While  specifically  different,  these  forms  do 
not  vary  much  one  from  another.  Fig.  9. 


236  ORDER   LITINIA 


10.  Nemella  ocellata  n.  sp.  .*      L       M          i-2  ~vi-*  Except  for  the  ceph- 
alic setae,  the  thin  cuticle  is  naked.     At  a  distance  from  the  anterior  extremity 
about  equal  to  the  width  of  the  head,  the  striation  of  the  cuticle  ceases,  so  that 
the  head  is  set  off  by  an  absence  of  striations,  as  well  as  by  a  slight  thickening 
of  the  cuticle.     The  neck  is  cylindroid.     From  the  faint  amphids,   an  inner 
element  can  be  traced  backward  to  near  the  base  of  the  head.     The  two  eye- 
spots  are  brownish  in  color,  and  each  has  a  colorless  lens.     The  oesophagus,  which 
has  an  indistinct  lining,  is  at  first  one-half,  near  the  nerve-ring  also  one-half, 
and  finally  three-fifths,  as  wide  as  the  corresponding  portion  of  the  neck.     There 
is  no  cardia.     The  intestine,  which  is  set  off  from  the  oesophagus  by  a  collum 
one-half  as  wide  as  the  neck,  becomes  at  once  three-fourths  as  wide  as  the  body. 
Its  wall  is  thick,  its  lumen  faint,  and  it  is  made  up  of  cells  of  such  a  size  that  prob- 
ably only  two  are  required  to  complete  a  circumference.    These  cells  are  packed 
with  colorless  granules  of  variable  size,  the  largest  of  which  are  about  one- 
twentieth  as  wide  as  the  body.     The  tail  is  conoid  to  the  convex-conoid  spin- 

i  .  .sn*±0r  neret,  which  at  its  base  is  one-third  as  wide  as  the  base  of  the 
-  tail,  and  has  somewhat  the  profile  of  a  swan's  head.  No  setae 
were  seen  on  the  tail.  At  their  widest  part  the  simple,  frail,  taper- 
ing, subacute  spicula  are  about  one-fifth  as  wide  as  the  corre- 
sponding part  of  the  body.  Their  proximal  ends,  which  are  mi- 
nutely cephalated  by  contraction  and  constriction,  appear  to  lie  a 
little  ventrad  from  the  body  axis.  They  are  supported  by  a  simple, 
frail,  slender,  faintly  S-shaped  accessory,  with  a  tapering  apophy- 
sis  (?)  extending  backward  from  the  spicula  at  an  angle  of  about  ninety  degrees, 
and  about  one-third  as  long  as  the  anal  body-diameter,  its  proximal  end  lying 
opposite  the  caudal  axis.  Whether  there  is  one  testis  or  two  remains  to  be 
determined. 

Habitat:  Eel-grass,  Biscayne  Bay,  Miami,  Florida,  U.  S.  A.     Flemming  to 
glycerine  jelly.    Fig.  10. 

11.  Porocoma  striata  n.  sp.  -V    'J-5      i-J>         i-?       1--  The  rather  thin  cuti- 
cle appears  to  be  destitute  of  setae  except  at  the  extremities.    The  body  is  tra- 
versed nearly  from  end  to  end  by  about  ten  to  twelve  wings.     Between  the 
wings  the  transverse  striae  seem  to  be  resolvable  into  excessively  minute  ele- 
ments.    In  addition  to  the  cephalic  setae,  there  is  a  ventral  seta-like  organ,  oppo- 
site the  sub-cephalic  setae  and  just  behind  the  excretory  pore.     This  is  a  little 
stouter,  longer,  and  more  blunt  than  the  cephalic  setae,  and  seems  to  have  a 
special  relation  to  the  excretory  pore.     The  mouth  is  surrounded  by  relatively 
thick,  minute  lips.     It  is  possible  that  a  more  or  less  vestigial  pharynx  extends 
back  to  near  the  cephalic  setae,  its  presence  being  indicated  by  a  slight  difference 
in  the  lining  of  the  canal,  and  by  a  break  in  the  musculature.     Posteriorly  the 
neck  is  cylindroid,    anteriorly  convex-conoid.     No  distinct  traces  of  amphids 
have  been  seen,  but  possibly  obscure  ones  exist  opposite  the  bases  of  the  lateral 
setae.    The  oesophagus  is  cylindroid,  then  conoid  in  its  posterior  eighth.     Near 
the  head  it  is  one-half,  near  the  nerve-ring  two-sevenths,  and  finally  three- 
fourths,  as  wide  as  the  corresponding  portion  of  the  neck.     Its  lining  is  indis- 
tinct.   There  is  a  flattish  cardia,  one-half  as  wide  as  the  base  of  the  neck.     The 
thick-walled  intestine  is  separated  from  the  oesophagus  by  a  collum  one-half  as 
wide  as  the  base  of  the  neck  and  becomes  at  once  two-thirds  as  wide  as  the  body, 
and  would  present  two  to  three  cells  in  cross-section.     Its  cells  contain  scattered 
granules  of  variable  size,   the  largest  of  which  have  a  diameter  about  equal 


POROCOMA,    LITONEMA  237 

to  the  width  of  two  of  the  adjacent  annules;  tessellated  effect  faint.  The  tail, 
which  tapers  from  in  front  of  the  anus,  is  conoid,  and  then  cylindroid  in  the  pos- 
terior half,  where  it  is  about  one-half  as  wide  as  at  the  base  Apparently  the 
ellipsoidal  caudal  glands  are  packed  in  a  close  tandem  in  the  anterior  fourth  of 
the  tail.  The  lateral  fields  are  one-half  as  wide  as  the  body.  The  elongated, 
outstretched,  granular  renette  cell  lies  one  to  two  body-widths 
behind  the  base  of  the  neck.  It  is  two  to  three  times  as  long  as  the  ,.j 
base  of  the  neck  is  wide  and  about  one-fourth  as  wide  as  long.  The 
broad  oblique  nerve-ring  is  accompanied  by  obscure  nerve  cells. 
While  both  ovaries  are  essentially  behind  the  vulva,  one  of  them  ~i  "  !JM 
extends  forward  a  distance  about  twice  as  great  as  the  correspond-  *TI ':!  H3i 
ing  body  diameter,  and  is  then  reflexed,  and  extends  backward,  so  *" 
as  to  lie  parallel  to  the  other.  The  medium-sized,  but  rather  conspicuous  vulva 
is  continuous  with  the  ventral  surface.  The  rather  strongly  cutinized  vagina 
extends  inward  two-fifths  the  way  across  the  body.  It  is  possible  that  the  nar- 
row, cylindroid  ovaries  are  reflexed  for  a  short  distance  near  their  blind  ends. 

Habitat:  Biscayne  Bay,  from  sponges  and  associated  material.     Flemming  to 
glycerine  jelly.     Fig.  11. 

II.  Order  Bolbinia 


12.  Litonema  nudum  n.  sp.  *••*/  3-5  *•?.  4-9  *•  -O--  The  presence  of  the 
two  wings,  which  begin  on  the  neck  and  end  near  the  anus,  is  indicated  by  two 
refractive,  longitudinal  markings,  which  occupy  a  space  equal  to  one-fourth  to 
one-third  the  width  of  the  body.  The  cuticle  is  entirely  naked.  There  appears 
to  be  a  vestigial  pharynx  nearly  as  long  as  the  base  of  the  head  is  wide, — simple, 
narrow,  tubular,  obscure.  The  neck  is  conoid.  Almost  on  the  front  of  the  head, 
but  near  its  margin,  there  are  two  minute,  lateral  pores,  which  may  possibly  be 
amphids.  Connected  with  these  pores  are  inner  tubular  elements,  which  may 
be  followed  backward  for  a  considerable  distance.  The  more  or  less  cephaloboid 
oesophagus  has  a  very  faint,  elongated,  posterior  swelling,  one-fourth  as  wide  as 
the  base  of  the  neck.  Near  the  pharynx  the  oesophagus  is  one-  ™/ 
third,  near  the  nerve-ring  one-eighth,  and  in  front  of  the 
cardiac  swelling  one-seventh,  as  wide  as  the  corresponding 
portion  of  the  neck.  The  optical  expression  of  the  lining  of  P" 
the  oesophagus  consists  of  two  distinct,  refractive  lines,  hav- 
ing a  distance  apart  about  equal  to  one-tenth  the  width  of  jnsc 
the  oesophagus.  There  is  no  cardia.  The  thick-walled  intes- 
tine presents  a  faint  lumen,  and  becomes  at  once  five-sixths 
as  wide  as  the  body.  Anus  continuous;  rectum  inconspicu-  " 
ous.  The  cells  of  the  intestine  are  packed  with  granules 
of  rather  uniform  size,  the  largest  of  which  are  one-seventh  *  750  i 
as  wide  as  the  body.  The  conoid  tail  tapers  from  in  front  of  the  anus.  There 
are  no  caudal  glands.  The  lateral  fields  are  probably  one-third  as  wide  as  the 
body.  The  excretory  pore  and  the  duct  leading  to  it  are  so  refractive  as  to  be 
easily  visible. 

Habitat:  About  the  roots   of  the   lady's  slipper,  Cypripedium  acaule  Linn., 
sphagnum  swamp,  Wisconsin,  U.  S.  A.    Flemming  to  balsam.     Fig.  12. 


238  ORDER   BOLBINIA 


-..-..T-..  ..  . 

13.  Hyalaimus  brevicollis  n.  sp.  ^  *•  *j,  5.1  1.7  •  "  The  colorless, 
naked  skin  displays  irregular  markings  and  a  finely  crenate  contour.  The  color- 
less, transparent,  conoid  neck  ends  in  a  truncate  head  without  setae  and  having 
very  flat  lips,  if  any.  Six  rather  conspicuous,  sub-marginal,  wart-like  papillae 
occur  in  a  circlet  on  the  front  of  the  head.  No  amphids  are  to  be  seen.  The 
mouth  is  a  mere  depression  one-sixth  as  deep  as  the  head  is  wide;  from  it  faint 
apophyses,  of  which  the  ventral  is  the  longest  and  most  conspicuous,  extend  back- 
ward and  seem  to  indicate  that  the  real  depth  of  the  pharynx  is  equal  to  the 
length  of  the  distinct  pharyngeal  bulb,  and  accordingly  the  dimensions  are  so 
given  in  the  above  formula.  The  somewhat  phalangiform  oesophagus  begins 
with  the  bulb  just  mentioned  as  filling  the  head,  and  which  is  two-fifths  as  long 
as  the  neck.  Behind  this  bulb  there  is  a  broad,  shallow  constriction,  the  remain- 
der of  the  oesophagus  being  fusiform  and  in  its  widest  part  two-thirds  as  wide 
as  the  neck.  For  a  short  distance  the  irregular  intestine,  three-fourths  as  wide 
as  the  body  and  separated  from  the  oesophagus  by  a  not  very  deep  constriction, 
appears  transparent  and  almost  bulbous.  The  cardiac  cavity  is  small  and  the 
cardia  very  flat.  The  large  cells  composing  the  intestine  are  filled  with  small 
granules,  displaying  no  very  definite  arrangement.  The  narrow,  colorless, 
transparent  rectum  is  thrice  as  long  as  the  anal  body-diameter,  and  has  a  dis- 
tinct lining.  The  ventral  excretory  pore  is  situated  as  far  behind  the  cardia 
as  the  head  is  in  front  of  it,  the  duct  in  the  immediate  vicinity  being  very  trans- 
parent and  distinct,  and  having  a  distinct  lining.  The  granular  lateral  fields 
are  one-fourth  as  wide  as  the  body,  and  from  head  to  tail  a  finely  crenulate, 
cuticular  wing  extends  along  each  lateral  line.  The  tail  of  the  female  is  conical 
to  the  pointed  terminus.  The  unusually  large,  flat,  elevated  vulva  is  two- 
thirds  as  wide  as  the  body,  and  from  it  the  vagina  extends  backward  a  distance 
greater  than  the  body-diameter.  The  two  straight  uteri  in  the  only  specimen 
seen  contained  six  to  eight  eggs,  each  a  little  longer  than  the  body  width,  and 
measuring  56-60  x  132-140  microns.  The  ovaries  extend  two-thirds  the  distance 
to  the  cardia  and  anus  respectively  and  contain  ova  arranged  single  file. 

Habitat:  Intestine  of  an  earth-worm,  Moss  Vale,  New  South  Wales,  Australia, 
April,  1894.  It  is  not  certain  that  this  nema  may  not  be  con-generic  with  one 
or  more  of  those  mentioned  by  earlier  authors  under  the  generic  names  Anguil- 
ula,  Nematodum,  etc.,  nemas  also  found  in  earth-worms,  but  insufficiently 
described;  hence  the  proposal  of  a  new  genus  for  its  reception. 


14.  Choronema  simplex  n,  sp.  L6  2A/  2-&  2-6  1-8  '  The  thin  cuticle  is 
entirely  naked.  The  wing,  which  begins  near  the  head  and  ends  on  the  tail,  is 
possibly  double  in  structure.  There  is  no  cardia.  The  rather  thick-walled 
intestine  is  separated  from  the  oesophagus  by  an  indistinct  collum  one -half  as 
wide  as  the  base  of  the  neck,  and  becomes  at  once  about  three-fifths  as  wide 
as  the  body.  It  has  a  faint  lumen  and  presents  few  cells  in  cross-section.  Anus 
subcontinuous;  rectum  inconspicuous.  The  cells  of  the  intestine  contain  scat- 
tered colorless  granules  of  variable  size,  the  largest  of  which  are  one-fifteenth 
as  wide  as  the  body.  In  the  specimen  examined  the  tail  was  destined  at  the  next 
molt  to  become  very  much  shorter,  so  that  the  anus  would  lie  at  about  90%, 
and  the  tail  would  therefore  be  about  four  times  as  long  as  the  anal  body- 
diameter.  Two  sublateral  papillae  existed  on  the  tail  nearly  opposite  each 
other. 

Habitat:  Soil  about  the  roots  of  plants,  Arlington  Farm,  Virginia,  opposite 


CHORONEMA,  IOTALAIMUS 


239 


M&ato 


the  city  of  Washington,  U.  S.  A.  Flemming  to  glycerine  jelly.  This  species,  of 
which  but  a  single  young  specimen  has  been  seen,  has  the  general  appearance 
of  being  a  deteriorated  Cephalobus  or  Diplogaster.  The  specimen  figured  was 

Mi  y°ung  and  in  process 
of  molting.  In  the 
left-hand  illustration 
the  excretory  pore, 
ex  p,  is  shown  in  its 
proper  position.  Nearly 
opposite  is  shown 
the  cast-off  duct  and 
pore  which  has  come 
into  its  present  posi- 
tionbyrotation  of 
the  loose,  shed  cuticle. 
Similarly,  in  the  right- 
hand  figure  the 
sloughed  anal  opening 
is  shown  opposite  the 
anus,  on.  The  caudal 
pores  eluded  observa- 
tion, but  that  they  were 
present  is  shown  by  the 
.  two  markings  at  ppl 
- m  in  the  cuticle  that  has 
been  shed.  Probably 
the  cuticle  has  length- 
ened, as  usual,  in  being 
shed,  and  the  pores  pre- 
JPft  sumably  occur  not  far 
behind  the  anus,  not- 
withstanding the  fail- 
ure to  see  them.  Ph, 
while  indicating  the 
....ttlt  (X  position  of  the  pharynx, 
also  indicates  an  ele- 
ment that  comes  to 
the  surface  ante- 
riorly (amphid?).  Fig. 

X  750 14. 

15.  lotalaimus  striatus  n.  sp.  Cuticle  naked;  the  striae  interrupted  by  well- 
developed  crenate  wings  one-fifth  as  wide  as  the  body.  Between  the  wings  is  a 
straightish  refractive  line,  due  to  a  continuous,  cuticular  structure.  On  some 
specimens  the  outer  contour  of  the  wings  consists  of  a  doubly  refractive  line. 
There  appear  to  be  four  faint,  submedian  cephalic  papillae.  The  amphids  are 
faint.  It  is  possible  that  there  is  a  vestigial  pharynx.  The  oesophagus  is 
very  faintly  cephaloboid  in  form.  The  anterior  two-fifths  is  cylindroid  and 
averages  only  about  half  as  wide  as  the  corresponding  portion  of  the  neck;  thence 
backward  the  oesophagus  diminishes  gradually  so  that  opposite  the  nerve- 
ring  it  is  only  about  one-fourth  as  wide  as  the  middle  of  the  neck.  It  continues 
to  have  this  diameter  for  some  distance,  but  finally  begins  slowly  to  expand,  so 


exp 


240 


ORDER   BOLBINIA 


that  at  last  it  is  about  half  as  wide  as  the  base  of  the  neck.  The  lining  is  faint, 
and  there  are  no  refractive  breaks  in  its  structure  to  indicate  the  presence  of 
vestigial  bulbs.  There  is  no  distinct  cardia.  The  intestine  becomes  at  once 
two-  to  three-fifths  as  wide  as  the  body.  It  is  composed  of  cells  containing 
scattered  groups  of  granules.  The  distinct  "lumen,"  instead  of  appearing  as 


m ? 


.93- 
3.1 


cavity  with 
refractive 


is.  _24.        "w         9*.  lining, 


it 


.trmd 


X750 


hmoe 


2.  $,4  3.5  3-5  -=V3.2  '  usually  does 
when  a  distinct  feature,  seems  to  have  a  dif- 
ferent structure  of  about  the  same  general 

•  fllMI  aPPearance-  From  the  slightly  depressed  anus 
the  conspicuous  rectum  extends  a  distance  about 

•w^  one    and   one-half  times   as  great  as  the   anal 

**  U  ^  J-T  J:«»«rt4-rt«          T^l-^xx  ]n-l-A-»nl   -C  „!,!,,    „ 


body  diameter.  The  lateral  fields  are  one-third 
as  wide  as  the  body.  It  appears  as  if  there  is  a  renette  cell  opposite  the  pos- 
terior portion  of  the  oesophagus.  The  tail  is  conoid  to  the  blunt  terminus,  which 
has  a  diameter  about  one-third  as  great  as  that  of  the  base  of  the  tail-.  There 
are  no  caudal  glands.  It  is  possible  there  is  a  pair  of  subventral  papillae  imme- 
diately behind  the  anus.  A  trifle  behind  the  middle  of  the  tail,  there  are  two 
faint,  lateral  innervations  close  together  on  each  side,  one  in  front  of  the  other, 
doubtless  connected  with  surface  papillae.  Ventrad  from  these,  it  is  possible 
there  is  a  third  papilla  belonging  to  the  same  group.  There  are  probably  one 
or  two  pairs  of  subventral  papillae  near  the  terminus.  The  proximal  ends  of 
the  tapering,  very  slightly  arcuate  spicula  are  bent  in  a  ventral  direction  so  as 
to  appear  to  lie  on  the  ventral  side  of  the  body-axis,  and 
so  appear  cephalated.  The  accessory  piece  is  more 
strongly  refractive  than  the  spicula  themselves,  the  frame- 
work of  which  is  not  particularly  conspicuous. 

Habitat:  About  the  roots  of  Bamboo,  Yuma,  Arizona, 
06    I!  •—?••--£-••      \  iimph  U.  S.  A.     Fig.  15,  above. 

16.  Bolbinium  brevicolle  n.  sp.  Cuticle  of  medium 
thickness,  naked.  Posterior  half  of  the  neck  cylindroid, 
anterior  half  convex-conoid.  Amphids  unusually  large, 
with  large  internal  connections  that  can  be  followed  back- 
ward for  some  distance.  The  narrow  oesophagus  contin- 
ues to  have  the  same  diameter  until  near  the  posterior, 
pyriform,  cardiac  swelling,  which  is  one-half  as  wide  as 
the  base  of  the  neck.  Many  of  the  nuclei  connected  with 
the  cells  of  the  neck  are  large  and  well-developed. 
In  the  dorsal  and  ventral  fields  there  are  strands  that 
appear  to  be  composed  of  closely-packed  cells.  The  car- 
diac bulb  has  no  distinct  valve. 


as -mi 


1-*      *       ^  The  spiculum  is  vestig- 

ial. In  a  variety  of  ways  this  nema  seems  related  to  the 
Mermithidae, — for  instance,  in  the  structure  of  the  mouth, 
the  cephalic  papillae,  the  amphids,  the  internal  structure  of  the  tissue  of  the 
neck  and  of  the  body,  the  absence  of  spinneret,  and  the  short,  rounded,  broad 
tail. 

Habitat:  Soil,  about  the  roots  of  citrus  plants,  Florida,  U.  S.  A.     Fig.  16. 


ANTOMICRON  241 

17.  Antomicron  pellucidum  n.  sp.  *•*  2-*  2~?  2-?  ^O  1-1"  Except  for  the 
cephalic  setae  the  cuticle  is  naked.  On  the  ventral  side  of  the  distinctly  pro- 
jecting wing  there  is  a  subordinate  line  to  be  seen  throughout  the  greater  por- 
tion of  the  length  of  the  body,  which  is  not  as  conspicuous  as  the  main  part  of 
the  wing.  Neck  conoid.  The  very  minute  pharynx  (?)  is  apparently  conoid; — 
whether  armed  or  not  is  unknown.  The  lip-region  has  not  been  examined  with 
success  on  account  of  deficient  material.  That  portion  of  the  amphid  inside  the 
two  ellipses  stains  more  strongly  than  the  tissues  elsewhere.  The  borders  of  the 
two  amphids  approach  each  other  so  closely  on  the  dorsal  side  that  they  some- 
times almost  touch,  in  fact  appear  to  be  connected  by  a  special  ^s^g^ 
cuticular  element.  Oesophagus  cylindroid  for  some  distance  back,  (^^^'^  '' 
and  then  expanding  rather  suddenly  to  form  an  almost  impercep- 
tible swelling  near  the  beginning  of  the  middle  third  of  the  neck; 
thereafter  it  diminishes  almost  imperceptibly  to  near  the  nerve- 
ring,  then  begins  to  expand  gradually  until  near  the  end,  where  it 
rapidly  expands  to  form  an  obscure,  small,  elongated,  pyriform 
cardiac  bulb,  almost  half  as  wide  as  the  base  of  the  neck.  There 
is  a  rounded  cardia  one-fourth  as  wide  as  the  base  of  the  neck. 
Considering  the  size  of  the  oesophagus  its  lining  is  prominent. 
The  intestine  is  separated  from  the  oesophagus  by  a  broad,  shallow  constriction, 
and  soon  becomes  half  as  wide  as  the  body,  and  apparently  would  present  only 
two  or  three  cells  in  cross-section.  The  lateral  fields  appear  to  be  nearly  one- 
third  as  wide  as  the  body.  It  seems  probable  that  a  renette  cell  occurs  at  some 
distance  behind  the  base  of  the  neck,  but  no  excretory  pore  has  been  seen.  The 
tail  of  the  male  is  conoid  to  near  the  terminus.  The  caudal  glands  are  located 
in  an  open  tandem  series  in  front  of  and  behind  the  anus.  The  eight  supple- 
mentary organs  occupy  a  distance  nearly  four  times  as  great  as  the  length  of  the 
tail;  each  is  a  nearly  straight,  cutinous  tube,  half  as  long  as  the  body  is  wide, 
arranged  at  an  angle  of  forty-five  degrees  with  the  body  axis,  and  having  its 
distal  extremity  protruding  backward  slightly  through  the  cuticle.  The  organs 
taper  slightly  in  the  vicinity  of  the  distal  end,  which  is  suddenly  somewhat 
ventrally  arcuate  at  the  terminus.  They  are  probably  protrusile,  though  they 
have  not  been  seen  in  a  protruded  position.  These  tubes  have  a  diameter  approx- 
imately equal  to  the  width  of  one  of  the  adjacent  annules  of  the  cuticle,  and  their 
proximal  ends  show  indications  of  an  attachment  extending  forward.  There  are 
a  number  of  specially-developed  setae  in  the  vicinity  of  the  anus;  especially 
prominent  are  two  submedian  setae,  one  on  each  side  of  the  anus,  one-third  as 
long  as  the  anal  body-diameter.  A  little  in  front  of  these  is  another  pair,  one  on 
each  side,  of  slightly  smaller  size,  and  on  the  tail  there  are  a  few  similar  ven- 
trally submedian  setae  of  smaller  size.  Spicula  a  little  longer  than  the  anal  body- 
diameter,  and  tapering  to  a  point  in  their  distal  thirds.  The  accessory  piece 
surrounds  the  spicula  in  their  distal  fourths,  and  then  extends  forward  to  the 
dorsal  side  of  the  body  from  the  middle  of  the  spicula  at  a  small  angle.  The 
appearance  of  the  proximal  portion  of  the  accessory  piece  somewhat  resembles 
that  of  the  proximal  ends  of  the  spicula,  though  it  is  straighter  and  more  solid. 
From  its  cephalated  proximal  end  a  muscular  strand  joins  the  body  wall  on  the 
dorsal  side  of  the  anterior  portion  of  the  tail.  The  posterior  testis  is  the 
smaller. 

Habitat:  Marine;  Punta  Arenas,  Pacific  Coast  of  Costa  Rica.  Unfortunately 
the  single  specimen  examined  is  of  such  a  character  that  the  details  of  the 
pharynx  must  be  left  undetermined.  Fig.  17. 


242 


ORDER    BOLBIXIA 


nrvr 


.9  •>. 


18.  Cyartonema  flexile  n.  sp.     Except  for  the  cephalic  setae  the  cuticle  is 
naked.     There  appears  to  be  a  circlet  of  six,  inconspicuous,    minute  papillae 

.15       5-1  8.4         -47f' 

'.ii'   1.3   '/i-i" 2.2 

.23      7.4 10.3...  "M. 

."83      'i.6'    /L6 1.7 

on  the  margin  of  the  head. 
The  form  and  structure  of 
the  gland  at  the  base  of  the 
narrow  oesophagus  is  remi- 
niscent of  the  salivary 
glands  in  Tylenchus.  The 
intestine  is  made  up  of  cells 
so  arranged  that  only  one 

to  two  are  required  to  build  a  circumference.  The  parts  of 
these  cells  are  so  differentiated  that  the  groups  of  granules  char- 
acteristic of  the  cells  occur  at  intervals  equal  to  one  to  two  body- 
diameters,  and  are  more  or  less  alternated  with  finely  granular 
intestinal  elements,  or  what  are  suspected  to  be  such  (see  Figure 
18,  int.?).  The  tail,  tapering  from  in  front  of  the  anus,  is  con- 
oid then  cylindroid  in  the  posterior  fifth.  Spinneret  with  min- 
ute setae.  A  single  caudal  gland  was  seen  near  the  middle  of 
the  tail.  A  few  very  inconspicuous  setae  were  observed  on 
the  tail.  Concerning  the  lateral  fields,  I  was  at  times  uncer- 
tain whether  the  cells  marked  intf  were  not  in  some  way  con- 
r&l  \>£f!\  '':\  nected  with  these  fields.  From  the  somewhat  elevated  vulva, 
the  relatively  large  vagina  leads  inward  two-fifths  the  way 
across  the  body.  The  eggs  are  three  to  four  times  as  long  as 
the  body  is  wide,  and  about  one-fourth  as  wide  as  long.  The 
broad,  more  or  less  cylindroid  ovaries  suddenly  taper  near 
the  blind  end.  They  contain  apparently  only  four  to  five  ova, 
*  500  arranged  single  file.  The  clavate  testis  is  about  two-thirds  as 

wide  as  the  body. 

Habitat:  Clean,  white  sand,  in  about  five  feet  of  water,  in  a  cove  near  the 
entrance  to  Buzzard's  Bay,  Mass.,  U.  S.  A.     Sublimate  to  balsam.     Fig.  18. 

set  to  (6) 

19.  Stilbonemabrevicollen.sp.    Annules 
plain,  retrorse  in  the  posterior  half  of 
the  body,  the  reverse   in  the   anterior. 
Exceedingly  short,   submedian,    slender 
setae  are  found  throughout   the  length 
of  the  body,  six  to  nine  annules  apart, 

those  at  the  extremities  being  somewhat     WA     ^^\'^"  /  '^^JUT  tib  1 

the  longer.  Neck  cylindroid.  Imme- 
diately around  the  mouth  there  is  prob- 
ably a  row  of  exceedingly  minute  papil- 
lae. In  most  of  the  neck  the  diameter 
of  the  oesophagus  hardly  exceeds  the  J0B...V  "  *750 

thickness  of  the  cuticle;  it  finally  expands  to  form  a  pyriform  bulb  about  three- 
fifths  as  wide  as  the  base  of  the  neck.     There  is  no  distinct  cardia.     The  very 


STILBONEMA,    LAXONEMA 


243 


narrow  intestine,  joined  to  a  depression  in  the  posterior  surface  of  the  cardiac 
bulb,  becomes  at  once  about  one-sixth  as  wide  as  the  body,  and  then  enlarges 

gradually  until  it  is  one-fourth  as  wide.  Its 
^X  750  cross-section  would  show  two  cells.  The  lat- 
eral fields  are  about  one-fourth  as  wide  as 
the  body,  and  contain'  numerous  nuclei. 
Nerve-ring  oblique.  Tail  conoid,  arcuate. 

•I.     3'  *L5  -M__     98. 

1:2— a;— lU" — i:5--^iT6  3-  "  Spicula  slender. 
"Acorn-shaped"  accessory  organs  (see  fig- 
ure) far  forward,  so  that  the  anterior  one  is 
a  little  behind  the  neck.  The  cup-shaped 
part  of  these  organs  has  slightly  different 
refractive  properties  from  the  "acorn"  itself, 
which  is  plainly  innervated. 

Habitat:     Shoal      in     Kingston     Harbor, 
Jamaica,  in  one  foot  of  water.     Sublimate  to  balsam.     Fig.  19a,  p.  242;  Fig.  196. 


20.  Laxonema  majum  n.  sp.  -6  .7  ^  .s'     "  Cephalic  cuticle  radi- 

ally striated;  the  basal  part  of  the  cephalic  setae  penetrate  and  interrupt  the 
cuticle.  Inside  the  cephalic  setae,  as  shown  in  the  sketch,  other  interruptions 
occur  in  the  cuticle;  possibly  in  some  cases  these  are  the  "stumps"  of  lost  setae. 
There  are  two  circlets  of  papillae  inside  the  cephalic  setae,  one  at  a  distance 
from  the  mouth  pore  somewhat  greater  than  the  thickness  of  the  body  cuticle, 
and  the  other  twice  as  far  away.  Oesophagus  nearly  cylindroid,  finally  expand- 
ing to  form  a  pyriform  cardiac  bulb  two-thirds  as  wide  as  the  base  of  the  neck. 
There  is  no  cardia.  The  intestine  soon  becomes  about  one-fifth  as  wide  as  the 
body;  at  a  distance  back  about  twice  as  great  as  the  body-diameter  it  expands 
and  becomes  thicker-walled  and  one-third  to  one-half  as  wide  as  the  body.  Its 
cross-section  is  composed  of  about  four  cells,  each  with  ten  to  twenty  brownish 

granules,   the  largest  of  pf/f .          or  ouph  set^cph(4) 

which  have   a  diameter  ^S^'X  ^st^^^fc^         j 

about  one-fourth  as  great  as  \\     :\         *^,\\    Wm     ^^     /] 

the  thickness  of  the  cuticle,  """*  \\^SM^^yifei^^A..^  . 

and   the   smaller  one-third 
to  one-fourth  -this  size.         ,    , 
Renette  unknown.     The          ^ 
lateral  fields  are  about  one- 
fourth  as  wide  as  the  body, 
and  contain  a  double  row  of 
nucleated   cells,    generally 
somewhat    rectangular     in 
form  and  separated  into  two 
series.     The    nerve-ring    is 
probably  a  little  behind  the  mai 
middle  of  the  oesophagus. 
The  tail  of  .the  male  is  X  750  hmoe'  setcdl  spa 

arcuate-conoid  and  ends  in  a  spinneret  destitute  of  striations  and  having  a 
length  about  equal  to  the  sum  of  the  widths  of  the  last  eight  striae.  The  tip  of 
the  spinneret  is  somewhat  differentiated,  and  its  core  presents  minute  longi- 
tudinal "striations"  which  end  just  anterior  to  the  terminal  pore.  The  caudal 


244  ORDER   BOLBINIA 

glands  are  probably  located  in  front  of  the  anus.  No  supplementary  organs 
have  been  seen.  There  are  no  caudal  papillae,  but  both  in  front  of  and  behind 
the  anus  there  are  a  number  of  ventrally  submedian  setae;  five  or  six  on  each 
side  of  the  anterior  half  of  the  tail;  while  an  equal  number  in  front  of  the  anus 
gradually  merge  into  the  scattered  setae  found  all  over  the  body.  The  proxi- 
mal ends  of  the  rather  stout  acute  spicula  are  somewhat  diminished  and  set 
off  by  a  broad  and  deep  constriction.  The  framework  composing  the  spicula  is 
relatively  massive.  The  rather  straight  accessory  piece  is  half  as  long  as  the 
spicula.  The  ejaculatory  duct  is  about  one-fourth  as  wide  as  the  body.  There 
appears  to  be  a  single  outstretched  testis,  though  there  remains  a  little  doubt 
on  this  point. 

Habitat:  Shoal  in  Kingston  Harbor,  Jamaica,  in  about  one  foot  of  water.     Fig. 
20,  p.  243.    Sublimate  to  balsam. 

:'.  .2-.8  .  .5-?  .   .  -*-'.  .  96.      22 

21.  Leptonemella  cincta  n.   sp.   '-      L- ">  w         |^"XiJ       '"  The   contour   is 
more  or  less  serrate,  the  annules  being  retrorse  posteriorly  and  the  reverse  ante- 
riorly.    In  addition  to  the  cephalic  setae  there  are  scattered  cervical  setae 
arranged  at  right  angles  to  the  surface  and  one-third  as  long  as  the  neck  is  wide. 
No  somatic  setae  have  been  seen.     Apparently  at  every  eight  to  ten  annules 
along  the  lateral  lines  there  are  pores,  each  with  its  longest  diameter  arranged 

,  „        tat  lh  transversely.     Seemingly  there  are  six,  very  minute,  more 

or  less  amalgamated  lips.  Posteriorly  the  neck  is  cylin- 
droid,  anteriorly  conoid.  Amphids  are  present  in  the 
form  of  straight  transverse  slits,  one-sixth  as  long  as  the 
corresponding  diameter  of  the  head,  and  located  between 
the  bases  of  the  submedian  cephalic  setae.  Their  presence 
and  their  form  is  proved  by  the  ribbon-shaped  outflow 
plainly  seen  issuing  from  each  amphid.  The  cylindroid 
oesophageal  tube  ends  behind  in  a  broad,  pyriform  cardiac 
bulb,  two-thirds  as  wide  as  the  base  of  the  neck.  There 
is  no  cardia.  The  thick-walled  intestine  is  separated 
from  the  oesophagus  by  a  collum  one-tenth  as  wide  as 
the  neck,  and  Becomes  at  once  one-fourth  as  wide  as  the 

•*  —          'ffm"   I     body.     Its  lumen  is  indistinct.     Its  cells  contain  fine, 

^^      rather  numerous  granules  of  more  or  less  uniform  size. 
set  l/Jtt  Wjyw  geverai  submedian,  slender,  tapering,  cuticular  "thorns" 

are  seen  on  the  tail,  each  about  one-fourth  as  long  as  the  anal  body-diameter. 
The  lateral  fields  are  one-fourth  as  wide  as  the  body.  The  nerve-ring  is 
accompanied  by  obscure  nerve  cells.  The  tail  is  more  or  less  conoid  from  the 
anus,  but  tapers  more  rapidly  in  the  posterior  half.  The  strong,  tapering, 
acute,  colorless  spicula  are  more  or  less  compound  in  structure  and  their  extremi- 
ties appear  to  lie  somewhat  ventrad  from  the  body  axis.  The  single,  slender, 
rather  strong,  simple  parallel  accessory  is  three-fifths  as  long  as  the  spicula. 

Habitat:  Sand,  Ocean  Beach,  Miami,  Florida,  U.  S.  A.     Flemming  to  glycerine 
jelly.    Fig.  21. 

.6       4.4        7-5         .-*-.       .9*-?  >iO.. 

22.  Cinctonema  tenue  n.  sp>  -fi*'  ' » J         1.4-^1.4  Cuticle  thin,  naked, 
its  striae  not  further  resolvable.     Neck,  cylindroid  posteriorly,  conoid  anteri- 
orly.    In  the  specimen  examined  the  lip-region  was  not  favorable  for  observation. 
Oesophagus  about  half  as  wide  as  the  head  and  continuing  to  have  this  diameter 
until  after  it  passes  through  the  nerve-ring,  behind  which  it  begins  to  increase 


CINCTONEMA,    CEPHALOBELLUS,   ANTICYATHUS 


245 


set  (4) 


a  little,  and  finally  enlarges  to  form  an  elongated,  pyriform  cardiac  bulb,  three- 
fourths  as  wide  as  the  base  of  the  neck.  The  intestine  is  very  narrow  where 
it  joins  the  center  of  the  posterior  face  of  the  cardiac  bulb, — hardly 
wider  than  one  of  the  annules.  Very  soon,  however,  it  becomes 
two-fifths  as  wide  as  the  body.  The  lateral  fields  are  about  one- 
fifth  as  wide  as  the  body  and  contain  nuclei,  two  of  which  placed  omphi 
side  by  side  would  span  the  field.  Tail  of  the  male  conoid;  on  it 
there  are  a  few  setae  in  front  of  the  anus.  The  rather  slender/75 
acute  spicula  are  about  one  and  one-fourth  times  as  long  as  the  anal  body- 
diameter. 

Habitat:  Sand  and  algae  near  East  Drive,  east  shore  of  Kingston  Harbor, 
Jamaica.     Sublimate  to  balsam.     Fig.  22. 


III.     Order  Cytolaimia. 


23.  Cephalobellus  papilliger  n.  sp.   *•        4-7      5.±  /      6.      >L6,    '  '"  Annules  of 
the  cuticle  2.2  microns  wide.     Head  continuous  with  the  conoid  neck.     There 
are  probably  six  lips,  but  no  labial  papillae  have  been  seen.     The  pharynx  resem- 
bles that  found   in  the   genus  Monhystera,    being    a  conoid  or  more  or  less 
pyramidal  depression  one-third  as  wide  as  the  head.     Oesophagus  cylindroid, 
one-fourth  as  wide  as  the  middle  of  the  neck,  joining  a  pyriform  cardiac  bulb 
two-thirds  as  wide  as  the  base  of  the  neck  and  containing  a  distinct  valve. 
Lining  of  the  oesophagus  rather  faint.     The  rather  thick-walled  intestine  is 
three-fifths  as  wide  as  the  body,  and  is  separated  from  the  neck  by  a  shallow, 
cardiac  constriction.     The  ventral  renette  cell  is  situated  just  in  front  of  the 
flexure  in  the  testis.     From  the  somewhat  elevated  anus  the  tail  is  conical  to 
the  acute  terminus.     A  pair  of  tall,  conical,  sub-ventral  papillae  are  located 
opposite  the  middle  of  the  spiculum.     Taken  altogether,  the  papillae  are  situ- 
ated as  follows:   1;  ()  1;  1.     Spiculum  slender,  somewhat  irregular,  twice  as  long 
as  the  anal  body  diameter,  placed  at  angle  of  forty-five  degrees  with  the  body- 
axis.     The  ejaculatory  duct  was  of  equal  length  with  the  testis,  and  was  con- 
nected with  it  by  a  tube  also  of  the  same  length. 

Habitat:  Intestine  of  the  larva  of  a  lamellicorn  beetle,  from  soil  under  cow- 
dung,  Moss  Vale,  New  South  Wales,  Australia.     1893. 

24.  Anticyathus  tenuicaudatus  n.  sp.     Body  wall  thick.     In  addition  to  ce- 
phalic setae  there  are  scattered  papilloid  cervical  setae.    Conoid  oesophagus  at  first 


set  (12) 


tTItt  two-thirds,  near  the  nerve-ring 
four-sevenths,  finally  four-fifths, 
as  wide  as  the  corresponding  por- 
tion of  the  neck.  Oesophageal 
lining  subdistinct.  There  is  a 
somewhat  obconoid  more  or  less 
"structureless'Mooking  anterior 
element  of  the  intestine  three- 
fourths  as  long  as  the  body  is  wide;  this  may  be  regarded  as  a  cardia  one-half  as 
wide  as  the  neck.  The  thick-walled  intestine,  which  has  a  faint  lumen,  is  set  off 


246  ORDER    CYTOLAIMIA 

by  a  collum  one-fifth  as  wide  as  the  base  of  the  neck,  and  becomes  more  or  less 
gradually  three-fourths  to  five-sixths  as  wide  as  the  body.  Its  cross-section  is 
composed  of  twenty  to  fifty  cells.  These  cells  contain  numerous  granules  of 
variable  size.  The  tail  tapers  from  in  front  of  the  anus;  it  is  first  conoid,  then 
cylindroid  in  the  posterior  fourth,  where  it  becomes  one-fifth  as  wide  as  at  the 
anus.  There  are  no  caudal  glands.  Fifteen  to  twenty  almost  invisible  setae, 
as  long  as  the  cuticle  is  thick,  occur  on  each  ventrally  submedian  line  on  the  tail. 
The  longitudinal  fields  are  one-third  as  wide  as  the  body.  Near  the  excretory 
pore  is  an  ampulla  one-sixth  as  wide  as  the  corresponding  portion  of  the  neck. 
The  nerve-ring  is  accompanied  by  obscure  nerve-cells.  Vulva  medium-sized, 
more  or  less  elevated;  vagina  non-cutinized.  Near  the  proximal  end,  each  ovary 
presents  a  double  flexure,  occupying  a  distance  about  equal  to  one  body-width; 
thence  onward  the  ovaries  are  outstretched  in  opposite  directions,— at  last  not 
over  one-tenth  as  wide  as  the  body.  The  eggs  occur  in  the  uteri  about  nine  at  a 
time.  They  are  about  one-half  to  two-thirds  as  long  as  the  body  is  wide,  though 
they  are  often  so  crowded  together  in  the  uterus  that  they  appear  wider  than 
long.  The  narrow  tapering  ovaries  contain  seventy  to  eighty  ova,  arranged 
single  file.  The  strong,  rather  simple,  stoutish,  tapering,  rather  blunt  spicula 
are  as  long  as  the  anal  body-diameter,  and  are  so  placed  that  their  proximal  ends, 
which  are  cephalated  by  expansion,  appear  to  lie  somewhat  dorsad  from  the  body- 
axis.  At  their  widest  part  the  spicula  are  about  one-eighth  as  wide  as  the  corre- 
sponding portion  of  the  body;  the  apophysis  is  more  or  less  uniform,  and  one- 
fourth  as  long  as  the  anal  body-diameter,  so  that  its  proximal  extremity  appears 
to  lie  opposite  to  or  dorsad  from  the  axis  of  the  tail.  The  25  supplementary 
organs,  hardly  more  than  innervations,  are  papilloid  and  of  slight  elevation, 
rather  farther  apart  anteriorly,  and  occupy  a  distance  five  to  six  times  as  great  as 
the  corresponding  body-diameter.  There  is  a  single  papilla-like  ventral  seta 
close  to  the  anus. 

Habitat:  Sand,  Coco-plum  Beach,  Miami,  Fla.,  U.  S.  A.     Flemming  to  glycer- 
ine jelly.     Fig.  24,  p.  245. 

25.  Neurella  simplex  n.  sp.  Striae  resolvable  with  great  difficulty  into  second- 
ary elements.  The  narrow,  sharply-defined  wings  begin  near  the  head  and  end 
on  the  tail.  The  cuticle  appears  to  be  naked,  except  that  at  the  base  of  the 
amphids  there  are  elements  of  problematical  significance  and  number.  The  neck 
.2  8.7^  ij.  ?57.'  M.  is  cylindroid  posteri- 

.3      1.2 v  1.2         1.7        1.2  1-  ""     orly,  conoid  anteriorly, 
2     s  3    13.        "=n         92.  — convex-conoid  toward 

'  '.^""i-V^'iz  i.i'^i.z1'  the  head.  There  seem 
to  be  three  lips  surrounding  the  somewhat  irregular  but 
more  or  less  distinct,  relatively  small  pharynx.  Oesoph- 

U)/ *W,/    agus  cylindroid;  at  first  one-half,  near  the  nerve-ring 
i@k$jjll      one-third,  as  wide  as  the  corresponding  portion  of  the 
V*1  m  neck;  its  lining  is  indistinct.    The  separation  between 

the  oesophagus  and  the  intestine  was  not  very  clear-cut.  The  thick-walled 
intestine  gradually  becomes  one-half  as  wide  as  the  body;  its  section  is  made  up 
of  two  cells  containing  scattered  granules  of  variable  size,  the  largest  about 
one-eighth  as  wide  as  the  body.  Not  until  near  the  middle  of  the  body  does  the 
intestine  acquire  very  definite  characteristics.  Anus  more  or  less  elevated. 
Tail  of  the  male,  as  far  as  seen,  conoid;  apparently  only  its  tip  was  missing. 
Located  well  toward  the  middle  of  the  body  there  is  a  long,  granular  cell  empty- 


NEURELLA,    ZYGONEMELLA          .  247 

ing  forward;— probably  the  renette  cell.     Excretory  pore  unknown.     Nerve-ring 
oblique,  accompanied  by  distinct  cells  arranged  in  groups. 

Habitat:  "Sea-grass,"  shoal,  two  miles  off,' Key  West,  Florida,  U.  S.  A.  Sub- 
limate to  balsam.  The  view  of  the  tail  of  the  female  was  slightly  foreshortened' 
the  formula  must  be  interpreted  accordingly.  Fig.  25,  p.  246. 

^.4_  _  _7_.3_  J3.6 -^t-"  _  <&.&_  >  1  2 

26.  Zygonemella  striata  n.  sp.  3.,i  4.1  4.6"  5.3—^3.6  "  In  addition  to  the 
cephalic  setae,  scattered  on  the  anterior  part  of  the  neck,  there  are  a  consider- 
able number  of  other  similar  setae,  some  of  which  are  longer  than  those  near  the 
margin  of  the  head.  Lips  three,  massive  but  low,  faintly  bi-lobed;  within  these 
there  is  a  rather  broad  inner  mouth  consisting  of  three  soft,  low,  flat  lobes,  which 
appear  to  be  extensions  of  the  tissue  of  the  oesophagus.  These  latter  present 
faint  refractive  elements,  the  expression  of  minute  foldings  of  the  lip  tissues, 
that  make  possible  the  great  expansion  necessary  for  the  deglutition  of  the  rela- 
tively large  diatoms  constituting  the  food.  In  appearance  the  pharynx  closely 
resembles  the  lumen  of  the  oesophagus.  It  would,  in  fact,  be  indefinable,  were  it 
not  for  the  pharyngeal  swelling  which  is  half  as  wide  as  the  head,  that  is  to  say, 
a  very  little  wider  than  the  remainder  of  the  oesophagus.  Immediately  behind 
•the  pharyngeal  swelling  the  oesophagus  diminishes  gradually,  so  that  where  it 
passes  through  the  nerve-ring  it  is  about  set  ft  (6?) .. 
two-fifths  as  wide  as  the  neck;  thence 

onward  it  is  cylindroid.  The  lining  of  the  /  lfl}  -^  •»  .( 
oesophagus  is  a  conspicuous  feature 
throughout  its  length.  The  tubular  cardia 
is  prominent,  about  one-fourth  as  wide  as 
the  base  of  the  neck,  and  about  one  and 
one-half  times  as  wide  as  long.  The  intes-  X  75( 
tine  is  almost  at  once  fully  half  as  wide  as  the  body  and  is  separated  from  the 
oesophagus  by  a  broad  and  deep  constriction.  Its  cross-section  probably  com- 
prises only  two  cells.  The  cells  contain  scattered  granules  of  small  size  and 
rather  uniform  diameter.  The  lateral  fields,  about  one-fourth  as  wide  as  the 
body,  contain  cells  packed  with  fine  uniform  granules.  Renette  unknown.  The 
tail  of  the  male  is  conoid  in  such  fashion  that  at  the  beginning  of  the  final  third 
it  has  a  diameter  about  equal  to  the  width  of  two  of  the  corresponding  annules; 
thence  onward  it  is  very  nearly  cylindrical.  The  anus  is  slightly  raised, — its 
posterior  lip  elevated.  The  caudal  glands  are  packed  in  a  tandem  series  opposite 
the  anus  and  occupy  a  space  somewhat  longer  than  the  anal  body-diameter; 
their  ducts  are  narrow.  Spicula  acute,  not  quite  as  long  as  the  anal  body-diam- 
eter; their  width  about  equal  to  the  width  of  one  of  the  adjacent  annules.  They 
taper  in  the  distal  fourths  to  slender,  acute  points.  The  posterior  testis  is  only 
about  half  as  long  as  the  anterior.  Ten  unicellular  glands  are  a  prominent  fea- 
ture of  the  anatomy  of  the  male.  (1)  A  pair  of  clavate  glands  immediately 
behind  the  blind  end  of  the  reflexed  posterior  testis.  Each  of  these  glands  has  a 
length  nearly  equal  to  that  of  the  adjacent  body-diameter,  and  empties  through 
a  duct  extending  backward.  The  ducts  have  a  width  somewhat  greater  than 
that  of  one  of  the  adjacent  annules.  (2)  Just  behind  the  pair  of  glands  already 
mentioned  is  a  second  clavate  pair  of  larger  size  and  very  similar;  these  are  about 
half  as  wide  as  the  body  and  somewhat  longer  than  the  body  is  wide,  and  the 
ducts  extending  backward  from  them  have  a  width  greater  than  that  of  two  of 
the  adjacent  annules.  (3)  Behind  the  second  pair  of  glands  there  are  six  small, 
pyriform  glands,  i.e.,  a  set  of  three  on  each  side  of  the  body,  arranged  longitudi- 
nally close  together,  but  having  separate  ducts,  also  extending  backward.  It 


248  ORDER    CiTTOLAIMIA 

has  been  impossible  to  determine  with  exactitude  the  entire  course  of  the  ducts 
of  these  various  glands,  but  most  of  them  have  been  seen  to  be  connected  with 
the  rectum,  and  all  are  believed  to  be  so  connected,  though  it  is  possible  that 
some  of  them  may  deliver  into  a  common  duct  before  reaching  the  rectum.  As 
to  the  structure  of  these  glands,  the  description  of  one  of  them  will  answer  fairly 
well  for  all  the  others.  In  the  fixed  specimens,  the  anterior  extremity  of  each 
contains  a  spherical  nucleus  with  a  strongly  staining  nucleolus :  the  nucleus  lies 
in  the  midst  of  chromatin  matter  which  stains  rather  strongly  with  acid  carmine. 
The  nucleus  and  chromatin  occupy  the  anterior  fourth,  or  third,  of  the  glandu- 
lar cell.  The  remainder  of  the  contents  is  of  a  uniformly  fine,  granular  nature. 
This  granulation  is  also  characteristic  of  all  the  ducts. 

Habitat:  Punta  Arenas,  Pacific  Coast  of  Costa  Rica.     Diatomivorous.     Sub- 
limate to  balsam.     Fig.  26,  p.  247. 

27.  Margonema  ringens  n.  sp.     Striae  unaltered  on  the  lateral  fields.     Cuticle 
apparently  naked,  but  it  is  possible  that  through  rough  handling  cephalic  setae 
fp/Jb  may  have  been  broken  off,  as  was  the  case  with  some  other 
,  specimens   in  the  same  collection.     Lips  three  and  double. 
Neck  cylindroid.     Amphids  faint.     Oesophagus  at  first  two- 
subait  thirds,  near  the  nerve-ring  one-half,  and  finally  two-thirds, 
_^  as  wide  as  the  corresponding  portion  of  the  neck;  its  lining 
indistinct.     There  is  a  faint,  rather  flat  cardia  about  half  as 
aw  son  wide  as  the  base  of  the  neck.     The  cross-section  of  the  thick- 
setsm  walled  intestine  is  made  up  of  two  cells.     These  transparent, 
elongated  cells  have  very  distinct  nuclei,  but  few  and  small 
X75°  inconspicuous  granules.     The  intestine  becomes  at  once  two- 
"-6Q- '      9*-2*t  7     thirds  as  wide  as  the  body,  and  is  separated  from 
.9  /  1.2      1.2         1.5        i-2  the  oesophagus  by  a  collum  two-thirds  as  wide  as 

the  base  of  the  neck,  and  has  a  faint  zig-zag  lumen. 

k. — p — 12: 'fl  ^-^>  1.5. .From  the  anus,  the  posterior  lip  of  which  is  ele- 
vated, the  prominent  rectum  extends  a  distance 

about  as  long  as  the  anal  body-diameter.  The  conoid  tail  tapers  from  the  anus. 
The  three  ellipsoidal  caudal  glands  lie  in  a  loose  tandem  in  the  anterior  two- 
fifths  of  the  tail.  There  are  no  caudal  setae.  The  lateral  fields  are  about 
one-third  as  wide  as  the  body,  and  contain  both  small  and  large  nuclei.  At  a 
distance  behind  the  neck  equal  to  twice  the  width  of  the  body  lies  the  ellip- 
soidal renette  cell,  which  is  about  as  long  as  the  body  is  wide  and  about  half 
as  wide  as  long,  It  empties  through  an  ampulla  about  as  long  as  the  neck  is 
wide,  and  about  one-fourth  as  wide  as  long.  This  latter  is  connected  with  the 
excretory  pore  by  a  very  short  duct.  The  nerve-ring  surrounds  the  oesoph- 
agus squarely,  and  is  accompanied  by  distinct  cells  apparently  not  very  defi- 
nitely arranged.  From  the  somewhat  depressed,  more  or  less  continuous  vulva, 
the  tubular  vagina  extends  nearly  half  way  across  the  body.  The  vagina  is 
bifurcated,  each  branch  being  about  half  as  long  as  the  body  is  wide.  The 
uteri  are  narrow.  The  eggs  are  three-fifths  as  wide  as  the  body,  and  six  times 
as  long  as  the  body  is  wide.  The  narrow  ovaries  taper  but  little,  and  contain 
about  a  dozen  ova  approximately  in  single  file.  At  their  widest  part,  the  slen- 
der, acute  spicula  are  about  one-eighth  as  wide  as  the  corresponding  portion  of 
the  body.  Their  arcuate,  cephalic  portions,  viewed  in  profile,  appear  to  lie 
somewhat  ventrad  from  the  body-axis.  The  subarcuate,  rather  slender,  frail, 
simple  accessory  pieces  are  joined  together  at  the  anus.  The  separate  apophysis 


MARGONEMA,    LEPTOGASTRELLA 


249 


is  uniform  and  one-fourth  as  long  as  the  corresponding  body-diameter.  There 
are  thirty  to  forty  low,  about  equidistant  supplementary  organs,  of  such  a  char- 
acter that  the  ventral  contour  becomes  crenate  when  the  tail  end  is  incurved; 
the  crenations  are  then  nearly  contiguous.  There  are  a  few,  scattered  ventrally 
submedian  setae  on  the  tail.  The  acute  ends  of  the  spicula  are  minutely  and 
sharply  curved  through  an  angle  of  180  degrees  at  the  very  tip.  One  male  speci- 
men was  seen  in  which  there  were  two  renette  cells,  each  with  a  separate  duct  for 
some  distance. 
Habitat:  Salavery,  Peru.  Marine.  Sublimate  to  balsam.  Fig.  27,  p.  248. 

28.  Leptogastrella  pellucida  n.  sp.  Except  for  the  setae  near  the  head  and  on 
the  tail  of  the  male,  the  cuticle  appears  to  be  naked.  The  neck  is  cylindroid 
posteriorly,  becoming  faintly  convex-conoid  toward  the  rounded  head,  which 
may  be  set  off  by  an  almost  imperceptible,  broad  constriction  opposite  the  base 
of  the  pharynx.  The  membranous  lips,  are  either  six  in  number,  or  three  and 
each  two-parted.  The  oesophagus  is  cylindroid.  There  is  an  elongated  cardia, 
one-half  as  long  as  the  body  is  wide,  and  about  two-thirds  as  wide  as  long.  The 
intestine,  separated  from  the  oesophagus  by  a  shallow  constriction,  becomes 
at  once  two-fifths  as  wide  as  the  body,  and  then  diminishes  slightly  so  that  it  has 
about  one-third  the  width  of  the  body.  Its  cross-section  would  appear  to  be 
made  up  of  not  more  than  two  cells.  The  intestine  is  so  narrow  as  to  give  the 
nema  quite  an  unusual  appearance.  It  is  thick-walled  and  has  an  exceedingly 
narrow  lumen.  Its  cells  are  packed  with  exceedingly  minute  yellowish  granules. 
Correspondingly,  the  body-wall  is  unusually  thick  and  muscular,  and  slightly 
oblique  longitudinal  striations  due  to  the  refractions  of  the  muscular  fibres  can 


3-3 


..»9-?.?  1.2.. 


1.3        9.         »•....  .-«.  . 

'•2.  2.5         2.9  3-*        "   2- 

be  seen  throughout  the  length  of 
the  body.     The  lateral  fields 
appear  to  be  about  one-third  as 
wide   as   the  body.     The   renette 
has  not  been  seen.     Vulva  slightly       ^ 
elevated.     The  outstretched  ovary 
contains    forty    or    more     ova 
arranged    single    file.     The    blind  «/  cdl 
end  of  the  ovary  lies  not  far  behind 
the  nerve-ring.     The  eggs  occur- 
ring in  the  uterus  appear  to  be  <K  ............. 

about  as  long  as  the  body  is  wide 
and    one-third    to    one-fourth    as 
wide    as    long.     The    tail    of    the 
male  is  conoid  to  near  the  termi- 
nus, where  it  has  a  diameter  about 
one-fifth  as  great  as  at  the  anus. 
Caudal  glands  are  located  in  the  base  of  the  tail.     There  are  no  supplementary 
organs,  nor  have  any  special  papillae  or  setae  been  seen  either  in  front  of  the 
anus  or  behind  it.     The  spicula  slide  in  tubular  accessory  pieces. 
Habitat:  Marine  mud,  San  Pedro,  California,  U.  S.  A.     At  first  glance  this 


250 


ORDER    CYTOLAIMIA 


nema  appears  to  be  a  typical  Monhystera,  but  careful  examination  fails  to  reveal 
any  such  well-developed  amphids  as  are  characteristic  of  Monhystera.  The 
spicula  are  quite  different  in  form  from  the  typical  spicula  of  Monhystera.  The 
intestine  also  is  highly  peculiar.  Occurs  also  at  Woods  Hole,  Mass.  Fig.  28,  p.  249. 

_L« 5-_3___»-_.._r_8*"_ 'i  >m  i.  .. 

29.  Dactylaimus  aequalis  n.   sp.  ^6      2.2     2.3         2.5       2.  Cuticle  naked. 
Three  of  the  six  lips  are  somewhat  more  substantial  than  those  alternating  with 
them.     Distal  thirds  of  the  lips  free,  the  remaining  n/ 

portions  webbed.  From  the  head,  the  oesophagus  con- 
tinues to  have  the  same  diameter  to  near  the  oblique 
nerve-ring,  but  then  begins  to  swell  gradually  so  that  fh 
finally  it  is  two-thirds  as  wide  as  the  base  of  the  neck. 
There  is  a  small  cylindroid  cardia.  The  intestine, 
separated  from  the  oesophagus  by  a  deep  constriction, 

becomes  at  once  about  two-thirds  as  wide  as  the  body.  ~^=^f^-  ..^,  .. 
Its  circuit  appears  to  comprise  about  four  cells.  The  ^  •••• 
lumen  of  the  intestine  presents  a  refractive  and  distinct  contour.  From  the 
inconspicuous,  slightly  depressed  anus,  the  rectum  is  considerably  shorter  than 
the  anal  body-diameter.  The  distinct  lateral  fields  are  about  one-third  as  wide 
as  the  body  and  contain  numerous  cells  whose  nuclei  are  arranged  in  two  indis- 
tinct rows  along  the  margins  of  the  field,  which  they  fill  fairly  well.  Renette 
unknown.  The  description  is  derived  from  a  single  young  female,  with  the 
vulva  in  process  of  development.  The  tail  is  conoid  in  such  fashion  that  at  a 
distance  from  the  anus  about  five  times  as  great  as  the  length  of  the  anal  body- 
diameter,  where  the  annules  vanish,  it  has  a  width  about  one-sixth  as  great  as 
at  the  anus.  An  indefinite,  but  probably  not  considerable  portion  of  the  tail 
of  the  specimen  examined  was  possibly  missing.  Hence,  the  above  formula  may 
be  only  approximately  correct.  The  following  formula  is  in  terms  of  absolute 
lengths  expressed  in  microns:  }]•____ ?*_•___ w_- *?_• ^niojo. 

Habitat:  Fine  marine  mud,  San  Francisco  Bay,  California,  U.  S.  A.     Sublimate 
to  balsam.     Fig.  29. 

1.1       «•»_»._    _     Y72._        86-«'517 

30.  Xenolaimus  striatus  n.  sp.    !•'      *•'  ~  *•'         *•*       £*     '  "    Cuticle  naked, 
and  complicated,  the  annules  retrorse  posteriorly  and  the  reverse  anteriorly. 
The  twelve  longitudinal  wings  extend  to  near  the  spinneret,  becoming  fewer  on 
the  tail.     The  thick,  somewhat  digitate  lips  are  united  by  a  membrane.     The 

M  &  Set  Jb  \  set  Sllbm  portion  of  the  head  containing  the  pharynx  is  pro- 
trusile  and  appears  as  if  surrounded  by  a  balustrade 
composed  of  the  anterior  annules  of  the  cervical 
cuticle.  The  large,  simple,  regular,  conoid  phar- 
ynx is  fully  three-fourths  as  long  as  the  head  is 
wide.  Each  of  the  six  lips  bears  a  two-jointed 
seta,  and  appears  to  be  armed  internally  with  a 
slender,  flexible  element  considerably  longer  than 
the  seta.  In  the  illustration,  what  appear  to  rep- 
resent two  minute  setae  on  the  foremost  annule  of 
the  neck  are  probably  the  optical  expression  of  an 
exceedingly  tenuous  membrane  surrounding  the 
head.  Although  the  oesophagus  was  not  plainly  seen,  it  is  evident  that  it  is  cyl- 
indroid as  in  Trachynema.  The  intestine  becomes  at  once  three-fourths  as  wide 
as  the  body.  The  anus  appears  continuous.  The  cells  of  the  intestine  con- 


XENOLAIMUS,    CYTOLAIMIUM 


251 


tain  scattered  granules  of  variable  size,  the  largest  of  which  are  one-half  as  wide 
as  one  of  the  annules.  The  conoid  tail  tapers  from  in  front  of  the  anus  and 
ends  in  a  spinneret. 

Habitat:  Marine  mud  from  near  the  government-dredged  cut,  Biscayne  Bay, 
Florida,  U.  S.  A.  Sublimate  to  balsam.  Fig.  30,  p.  250. 

31.  Cytolaimium  exile  n.  sp.  Cuticle  thin,  without  setae  except  those  on  the 
head.  Lips  with  thin  distal  flaps  as  in  Monhystera.  The  cylindroid  oesophagus 
is  at  first  three-fifths,  near  the  nerve-ring  one-half,  and  finally  three-fifths,  as 
wide  as  the  corresponding  portion  of  the  neck.  There  is  a  conoid  cardia  one- 
third  as  wide  as  the  base  of  the  neck.  The  thick-walled  intestine,  which  has  a 
faint  lumen,  becomes  at  once  three-fourths  as  wide  as  the  body.  Its  cells  contain 
scattered  granules  of  variable  size,  the  largest  of  which,  near  the  neck,  are  one- 
fifteenth  as  wide  as  the  corresponding  portion  of  the  body,  but  near  the  middle 
of  the  nema  are  one-tenth  as  wide  as  the  body.  The  conoid  tail  tapers  rather 
regularly  from  somewhat  in  front  of  the  anus,  but  faster  near  the  anus.  No 
clear  evidence  of  the  presence  of  caudal  glands.  The  lateral  fields  are  about 
one-half  as  wide  as  the  body.  The  narrow  nerve-ring  is  accompanied  by  obscure 
nerve  cells.  From  the  small,  continuous,  inconspicuous  vulva,  a  small,  more  or 
less  weak,  non-cutinized  vagina  extends  inward  one-third  the  distance  across  the 
body.  In  the  narrow,  tapering  ovaries,  the  ova  are  arranged  single  file.  Only 
one  egg  at  a  time  occurs  in  each  uterus.  The  eggs  are  three  times  as  long  as  the 
body  is  wide  and  appear  about  three-fourths  as  wide  as  the  body.  The  tail  of 
the  male  is  first  conoid,  then  cylindroid  in  the  posterior  two-fifths,  where  it  is 
one-third  as  wide  as  at  the  base.  The  somewhat  stout,  rather  blunt  spicula  are 
strong,  non-cephalated,  and  so  situated  that  their  proximal  ends  appear  to  lie 

:•      --...-V-       '-57-'      n.     (,     opposite    the 
•• • • • ^«*.i—  body-axis.    Ihere 

T  M     w       •*•••     95.5      .     isu  a  "fractive 
••-.- •*" ...^....«3.5..  short  element  in 

front  of  the  tips 

fUbfh  of  the  spicula.  Accessory  piece  slender,  appar- 
ently strong,  one-third  as  long  as  the  spicula. 
The  16  pairs  of  submedian,  equidistant,  discoid, 
slightly-elevated  supplements  are  not  cup- 
pli  shaped,  and  are  relatively  less  cutinized  than 
in  well-developed  Chromadora  supplements. 
The  posterior  pre-anal  pair  lies  opposite  the 
distal  parts  of  the  spicula.  Thence,  forward, 
X  750  placed  at  intervals  about  equal  to  three-fourths 
the  body-diameter,  the  organs  occupy  a  space 
eight  to  nine  times  as  long  as  the  anal  body-diameter.  The  post-anal  five  pairs 
occupy  the  anterior  three-fifths  of  the  tail.  The  discs  are  about  one-fourth  as 
wide  as  the  body,  and  one-fourth  as  wide  as  high,  the  distance  between  them  being 
about  one  and  one-half  times  their  diameter.  There  appears  to  be  an  innervated 
element  that  projects  from  near  the  center  of  each  disc.  The  ejaculatory  duct, 
which  is  co-extensive  with  the  pre-anal  supplementary  organs,  is  one-half  as  wide 
as  the  corresponding  portion  of  the  body.  The  vas  deferens  is  one-half  to  one- 
third  as  wide  as  the  body.  Each  testis  is  at  first  about  one-third  as  wide  as  the 
body  and  cylindroid,  but  afterwards  tapers.  The  anterior  testis  is  much  the 
longer. 

Habitat:  Sand-bar  opposite  Miami  River,  Biscayne  Bay,  Fla.,  U.  S.  A.  Sub- 
limate to  balsam.  Fig.  31. 


lit  (3) 


252 


ORDER   CYTOLAIMIA 


32o.  Rhabdocoma  americanum  n.  sp.  Type  species.  Cuticle  thin,  naked  except 
for  the  cephalic  setae.  Lips  three.  Wall  to  the  pharyngeal  cavity  in  optical 
section  showing  three  somewhat  thickened  elements,  that  are  possibly  minutely 
transversely  ribbed;  these  elements,  however,  are  very  smallfand  difficult  of 


resolution.  Neck  somewhat  conoid 
anteriorly.  Oesophagus  at  the 
nerve-ring  two-fifths,  at  the  cardia 
two-thirds,  as  wide  as  the  corre- 
,  spending  portion  of  the  neck,  and 
containing  glands,  as  is  indicated 
by  fine  granular  matter  in  branched 
dettUtfh .  U  trm  -^ffW/  X750  cavities.  Cardia  more  or  less 

spheroidal,  one-half  as  wide  as  the  base  of  the  neck.  The  rather  thick-walled 
intestine  presents  a  faint  lumen  and  becomes  at  once  about  one-half  as  wide  as 
the  body;  its  cross-section  presents  but  few  cells.  Anus  continuous;  rectum 
about  as  long  as  the  anal  body-diameter.  The  intestinal  cells  contain  granules 
of  variable  diameter,  the  largest  one-tenth  as  wide  as  the  body.  Doubly  refrac- 
tive granules  occur  in  all  parts  of  the  intestine,  but  are  not  numerous;  these  tend 
to  have  quadrate  contours  and  do  not  present  St.  Andrew's  crosses.  The  tail 
tapers  very  gradually  throughout,  commencing  well  in  front  of  the  anus.  Ren- 
ette  unknown.  There  is  an  anterior  rudimentary  branch  to  the  female  sexual 
organ,  about  as  long  as  the  body  is  wide.  From  the  rather  large,  more  or  less 
depressed  vulva  the  well-developed  cutinized  vagina  extends  inward  three-fifths 
the  distance  across  the  body.  The  elongated  eggs  are  twice  as  long  as  the  body 
is  wide.  The  broad,  cylindroid  ovary  reaches  three-fourths  the  distance  back 
to  the  vulva  and  contains  very  many  ova,  those  of  the  two-thirds  next  the  uterus 
being  arranged  single  file.  The  frail  spicula  are  about  one  and  two-thirds  times 
as  long  as  the  anal  body  diameter  and  are  rather  wide  apart.  Accessory  pieces 
faint.  Supplements  papilloid,  twelve  to  sixteen,  occupying  a  distance  in  front 
of  the  anus  ten  to  twelve  times  as  long  as  the  body-diameter,  while  a  second 
series  of  about  eight,  occurs  on  the  neck.  The  members  of  the  anal  series  are 
somewhat  farther  apart  anteriorly;  of  the  cervical  series,  posteriorly. 
Habitat:  Sand  among  mussels,  Devil's  Island,  Woods  Hole,  Mass.  Fig.  32. 


6.  Rhabdocoma  macrurum  n.  sp.  L  J-3  i.*  %-^i.j  •  "  Very  closely 

resembles  the  preceding,  but  differs  in  the  following  respects:  straight  setae, 
nearly  as  long  as  the  head  is  wide,  digitate,  with  a  minute  setose  mucro;  amphids 
a  trifle  farther  forward,  somewhat  elongated;  apparently  four,  submedian,  min- 
ute, short  setae  opposite  the  posterior  margin  of  the  amphids;  accessory  pieces 
one-half  as  long  as  the  spicula  and  parallel  to  them. 

Habitat:  Sulphurous  sand,  Bay  of  Naples,  toward  Vesuvius,  1888. 

.35       2.6         7.6        l°-44-"        81. 


33.  Didelta  maculatum  n.  sp.  •»  h*  L5  J-8  1>2  *  "  Cuticle,  which  is 
above  medium  thickness  and  naked  except  for  the  setae  on  the  head,  is  charac- 
terized by  the  presence  of  peculiar  transversely-elongated  refractive  subcuticular 


DIDELTA,    DASYNEMA 


253 


markings,  reminiscent  of  the  bubbles  in  defective  window  glass.  The  simple, 
subregular,  somewhat  asymmetrical,  napiform  pharynx  is  about  one-third  as  wide 
as  the  head.  On  the  dorsal  side  of  the  base  of  the  pharynx  there  is  a  more  or  less 
glottoid,  low,  flat  elevation,  so  that  the  more  or  less  refractive  dorsal  wall  of 
the  pharynx  appears  only  about  half  as  v^  ~Jt  f*\ 
long  as  the  ventral  wall.  Posteriorly  J^t/* 
the  neck  is  cylindroid,  anteriorly,  more 
or  less  conoid.  The  elliptical  amphids 
are  in  reality  spirals  of  about  one  wind. 
They  occur  on  large,  somewhat  equilat- 
erally  triangular  or  deltoid  areas  on  the 
sides  of  the  head;  hence,  the  name 
Didelta.  The  oesophagus  is  at  first 
about  three-fourths,  near  the  nerve- 
ring  one-half,  and  finally  two-thirds,  as 
wide  as  the  corresponding  part  of  the 
neck.  The  lining  is  distinctly  indi- 
cated by  a  more  or  less  zig-zag,  refrac- 
tive line;  the  musculature  is  coarse  and 
colorless.  There  are  no  valves,  and  there  is  no  cardia.  The  thick-walled  intes- 
tine, which  has  a  distinct  refractive  lining,  becomes  at  once  three-fourths  as 
wide  as  the  body;  its  cross-section  being  composed  of  about  six  cells.  It  is  sep- 
arated from  the  oesophagus  by  a  collum  one-third  as  wide  as  the  base  of  the  neck. 
The  cells  of  the  intestine  are  packed  with  more  or  less  uniform  granules,  having 
a  diameter  about  one-ninetieth  that  of  the  body.  Arranged  in  elliptical  clusters, 
they  give  rise  to  a  distinct  tessellation.  The  tail,  which  tapers  from  the  anus, 
is  first  conoid,  and  then  more  or  less  cylindroid  in  the  very  narrow  posterior 
half.  It  really  tapers  throughout,  but  is  nearly  cylindroid  in  the  setaceous 
part.  There  is  no  spinneret.  The  lateral  fields  are  about  one-fourth  as  wide 
as  the  body.  The  nerve-ring  is  of  medium  size,  and  is  accompanied  by 
obscure  nerve  cells.  From  the  rather  inconspicuous,  but  somewhat  elevated 
vulva,  the  cutinized  vagina  leads  inward  two-fifths  the  distance  across  the  body. 
The  tapering  ovaries  were  not  favorable  to  detailed  observation. 

Habitat:  "Sea-grass,"  shoal,  two  miles  off  Key  West,  Florida,  U.  S.  A.     Flem- 
ming  to  glycerine  jelly.     Fig.  33. 


setsubcph  (6) 


X750 


18.4 
3-7 


62.5 
14 


34.     Dasynema  sexalineatum  n.  sp.     3'8  '    3:7.         *i       2.4  Striae  resolv- 

able into  secondary,  elongated  elements.     Annules  retrorse  posteriorly,  and  the 
reverse  anteriorly.     Cuticle  naked  except  for  the  setae  on  or  near  the  head. 
yl!  Lips  three,  more  or  less  distinct,  thin,  apparently 
acute,  possibly  conoid,  mobile;  the  appearance  is 
I  that  of  three  segments  of  the  head,  each  armed  at 
the  summit  with  a  short,  inward-pointing,  dark, 
cutinized  apex,  having  an  inward  stroke.     There 
does  not  appear  to  be  a  distinct  cardia,  but  a  num- 
,lf,    }  -~^j,.        -    /r  °f  small  cells  forming  the  beginning  of  the 
intestine  are  manifestly  different  in  structure  from 

those  directly  behind.  The  rather  thin-walled  intestine,  which  has  a  more  or 
less  distinct,  refractive  lumen,  soon  becomes  two-thirds  as  wide  as  the  body, 
and  its  cross-section  is  composed  of  two  to  four  cells  in  which  there  are  few  or 


'xtqAM 
setsubcph 
mph 


254 


ORDER    CYTOLAIMIA 


mr 


*375 


no  granules.  From  the  anus,  the  posterior  lip  of  which  is  elevated,  the  promi- 
nent rectum  leads  inward  a  distance  one  and  one-half  times  as  great  as  the 
anal  body-diameter.  The  tail  is  sub-conoid,— at  first  co- 
noid, then  more  or  less  cylindroid.  The  elongated  caudal 
glands  appear  to  lie  in  the  anterior  half  of  the  tail. 

Habitat:  Eel-grass,  Woods  Hole,  Mass.,  U.  S.  A.  Sub- 
limate to  balsam.  Described  from  a  young  specimen. 
Fig.  34a,  p.  253;  Fig.  346. 

35.  Linhomoella  exilis  n.  sp.  The  shorter  cephalic  setae 
are  differentiated  at  the  extremity,  suggesting  that  they 
bear  special  sensory  organs.  Cuticle  naked  except  for  the 
setae  on  or  near  the  head.  Lips  apparently  confluent. 
Possibly  there  are  papillae  immediately  around  the  mouth 
opening.  It  sometimes  appears  as  if  there  is  a  minute 
pharynx  like  that  of  Monhystera,  but  this  may  be  a  decep- 
tion due  to  the  structure  of  the  front  part  of  the  oesopha- 
gus; possibly  there  is  no  true  buccal  cavity.  Neck  cylin- 
droid. The  more  or  less  cylindroid  oesophagus  is  at  first 
three-fifths,  near  the  nerve-ring  two-fifths,  and  finally  two- 
thirds,  as  wide  as  the  corresponding  portion  of  the  neck. 
tt  It  is  colorless  and  has  a  fine  musculature.  The  cylindroid 
cardia  is  three-fourths  as  wide  as  the  neck.  The  intestine,  which  is  separated 
from  the  oesophagus  by  a  collum  three-fifths  as  wide  as  the  base  of  the  neck, 
becomes  at  once  three-fourths  as  wide  as  the  body.  Near  its  anterior  end,  how- 
ever, there  is  a  broad,  shallow  constriction,  in  which  region  its  lumen  is  faint. 
Anteriorly  the  walls  are  thick,  while  posteriorly  they  are  thin.  A  cross-section 
of  the  intestine  is  probably  made  up  of  about  three  cells.  These  cells  contain 
scattered  granules  of  variable  size,  the  largest  of  which  are  about  one-twelfth 
as  wide  as  the  body  and  appear  to  have  the  structure  of  spherical  shells.  The 
arcuate  tail  tapers  from  the  anus  to  the  terminus,  where  it  is  one-fourth  as  wide 
as  at  the  anus.  Caudal  ,  It 

glands  were   not   seen.  : ' "•  ->3-3 

The    caudal    setae    are ' 

very  minute  and  very  :2- ••  ^  •  • ''-1 *.^^.*fci 

inconspicuous, — five   to 

six  on  each  ventrally  submedian  line.    From  the  con- 
spicuous, fairly  large,  elevated  vulva  the  cutinized 

vagina  extends  one-third  the  distance  across  the  body.  w 

The  slender  eggs  are  ten  times  as  long  as  the  body  is 
wide,  and  appear  to  be  about  three-fourths  as  wide  W ••• 
as  the  body.    The  narrow  tapering  ovaries  contain 
twenty  or  more  ova  arranged  single  file.    The  proxi-  ompu. 
mal    extremities    of    the    stoutish,    tapering,    acute, 
rather  strong  spicula  appear  to  lie  ventrad  from  the  x  750 
body  axis,  and  are  not  materially  cephalated.    The 

part  of  the  accessory  piece  near  the  spicula  is  refractive;  the  apophysis,  however, 
is  faint,  and  a  little  more  than  half  as  long  as  the  anal  body-diameter.  As  to 
supplementary  organs,  there  are  almost  invisible  ventral  innervations,  equi- 
distant and  separated  from  each  other  by  spaces  about  two-thirds  as  great  as 
the  body-diameter.  The  ejaculatory  duct  and  vas  deferens  are  about  one-third 
as  wide  as  the  body.  The  tapering  testes  are  very  narrow. 


LINHOMOELLA,    NANNOLAIMUS  255 

Habitat:  Sand-bar,  Biscayne  Bay,  off  the  mouth  of  the  Miami  River,  Florida, 
U.  S.  A.  Flemming  to  glycerine  jelly.  Fig.  35,  p.  254.  The  almost  impercep- 
tible constriction  occurring  in  the  cephalic  region,  as  shown  in  the  illustration, 
is  somewhat  more  marked  when  seen  dorso-ventrally;  the  amphids  are  located 
in  the  midst  of  a  broad  and  shallow  depression. 


...-        _____  .....     1      .. 

36.  Nannolaimus  guttatus  n.  sp.  /1A     U5      l-5          *•*•       *-5  Cuticle  of  me- 

dium thickness,  naked  except  for  the  cephalic  setae,  of  which  there  is  a  circlet  of 
ten,  with  a  circlet  of  six  immediately  preceding  it.  There  are,  however,  a  few, 
scattered  setae  on  the  neck,  one-third  as  long  as  the  neck  is  wide,  arranged  at 
right  angles  to  the  surface.  Lips  confluent,  very  small,  thin  and  minute,  prob- 
ably six  in  number.  No  labial  papillae  have  been  seen.  Pharynx  almost  non- 
existent, simple,  conoid.  Neck  cylindroid.  The  oesophagus  is  at  first  one-half, 
near  the  nerve-ring  two-sevenths,  and  finally  two-thirds,  as  wide  as  the  corre- 
sponding portion  of  the  neck;  its  lining  is  subdistinct,  wtnJi/fi) 

its  musculature  fine  and  colorless.     There  is  a  hemi-     ""  •-••»«-*i*L  ' 
spherical  cardia,  one-fourth  as  wide  as  the  base  of  the 
neck.     The  thick-walled  intestine,  which  is  set  off  by  a 
collum   one-fourth   as  wide   as   the  base   of  the  neck, 
becomes  at  once  two-thirds  as  wide  as  the  body.    Ante- 
riorly its  lumen  is  faint,  but  posteriorly  it  is  distinct,  set 
The  cross-section  of  the  intestine  is  composed  of  about 
three  cells.     The  granules  contained  in  these  cells  are 
scattered  to  numerous,    and   are  of  variable  size,    the 

largest  having  a  diameter  equal  to  the  width  of  two  of  the  adjacent  annules. 
They  have  the  appearance  of  hollow  shells,  more  or  less  thick-walled.  The 
conoid  tail  tapers  from  the  anus  to  its  terminus,  which  is  one-third  as  wide  as 
its  base.  Though  the  caudal  glands  were  not  clearly  seen,  they  appear  to  be 
broadly  saccate  and  to  be  arranged  in  a  close  tandem  behind  the  anus  in  the  ante- 
rior half  of  the  tail.  There  appear  to  be  about  three  slender,  somewhat  cylin- 
droid, subacute  setae  on  each  submedian  line  on  the  tail.  The  lateral  fields  are 
two-fifths  as  wide  as  the  body.  The  huge  renette  cell  begins  at  the  cardia  and 
extends  backward  a  distance  equal  to  the  length  of  the  neck.  It  is  two-fifths 
as  wide  as  the  body,  and,  of  course,  is  not  reflexed.  It  is  granular  and  possesses 
a  large  nucleus.  The  elongated  ampulla  is  one-third  as  wide  as  the  head  and  emp- 
ties through  a  short  duct  near  the  base  of  the  lips.  Vulva  more  or  less  continu- 
ous, small;  cutinized  vagina  of  medium  size.  The  thin-shelled,  elongated  eggs 
are  probably  five  to  six  times  as  long  as  the  body  is  wide.  According  to  the  con- 
dition of  the  uterus,  the  broad  tapering  ovaries  reach  from  three-fifths  to  the 
whole  of  the  distance  back  to  the  vulva.  They  contain  about  a  dozen  ova 
arranged  more  or  less  single  file,  except  near  the  blind  end. 

Habitat:  Sand,  Cape  Florida,  Biscayne  Bay,  Florida,  U.  S.  A.  Flemming  to 
glycerine  jelly.  This  genus  resembles  Cyatholaimus  more  or  less  but  has  no 
onchia  and  the  excretory  pore  is  farther  forward.  The  labial  features  are  small- 
er and  less  definite  than  in  Cyatholaimus.  It  is  notable  also  that  no  pores  are 
to  be  seen  in  the  cuticle.  The  oesophagus  ends  behind  in  an  almost  impercep- 
tible elongated  swelling.  The  color  of  the  ocelli,  through  oversight,  was  not 
noted.  Until  the  male  is  known,  the  affinities  will  remain  doubtful.  Fig.  36. 


256  ORDER   ISOLAIMIA 

IV.  Order  Isolaimia 


37.  Rhadinema  flexile  n.   sp.     •«      »-s/    1-2         1.5    •»  i-3         '     Cephalic  setae 
3-jointed;  cuticle  otherwise  naked.     The  thick,  small  lips  confluent.     Pharynx 
exceedingly  minute,  two-thirds  as  deep  as  the  head  is  wide;  wall  characterized 
by  six  longitudinal  elements  of  minute  size,  exactly  parallel  to  the  axis  of  the 
head,  so  that  the  pharynx  appears  to  be  a  more  or  less  shallow,  cylindroid  or 

"Xt  Ctth  (4)  Prism°id  CUP>  two-thirds  as  deep  as  wide.  The  lining  of 
the  oesophageal  canal  is  more  or  less  modified  as  far  back 
^fi/mtphlj)  as  the  base  of  the  amphids.  The  circumference  of  the 
amphids  is  almost  imperceptibly  broken  on  the  dorsal 
The  somewhat  cylindroid  oesophagus  is  almost 
imperceptibly  swollen  in  the  posterior  fifth.  At  first  it 
is  three-fifths,  near  the  nerve-ring  one-half,  and  finally  two-thirds,  as  wide  as 
the  corresponding  portion  of  the  neck.  The  lining  is  subdistinct.  There  is  a 
more  or  less  hemispherical  cardia  three-fifths  as  wide  as  the  base  of  the  neck. 
The  thick-walled  intestine,  which  has  a  distinct,  refractive,  more  or  less  zig-zag 
lumen,  becomes  at  once  three-fourths  as  wide  as  the  body.  Its  cells  are  packed 
with  uniform  colorless  granules  of  variable  size,  the  largest  of  which  are  one- 
sixteenth  as  wide  as  the  body.  They  do  not  give  rise  to  more  than  a  faint  tessel- 
lation. The  tail  is  conoid.  The  more  or  less  narrow  elongated  caudal  glands 
are  arranged  in  a  loose  tandem  behind  the  anus  in  the  anterior  third  of  the  tail. 
The  elongated  renette  cell  lies  at  a  distance  behind  the  base  of  the  neck  equal  to 
twice  the  body-diameter;  it  is  one  body-width  long,  about  one-third  as  wide  as 
long,  and  contains  a  rather  large  nucleus.  The  rather  broad  oblique  nerve-ring 
is  accompanied  by  somewhat  obscure  nerve  cells. 

Habitat:  Clear,  "white"  sand,  5  feet  of  water,  cove  at  the  entrance  to  Buz- 
zard's Bay,  Mass.,  U.  S.  A.    Sublimate  to  balsam.     Fig.  37. 

•4 ?•_»_ __">•_} 5. 3'j _  94. 7_ 

38.  Protrellus  aureus  n.  sp.     -7      *•*/     3-_         '•         i-'        "  Annules  as  much  as 
20  microns  wide.     Striae  are  visible  throughout  the  length  of  young  specimens, 
which  also  differ  from  the  adults  in  not  having  the  cuticle  inflated  on  the  neck. 
No  setae  or  amphids.     The  conoid  neck  ends  in  a  truncate  head,  bearing  a 
lip-region  set  off  by  constriction,  and  apparently  composed  of  six  lips.     There 
is  at  least  one  papilla  on  each  lip.     The  prismoid  pharynx  is  half  as  wide  as  deep. 
The  major  part  of  the  oesophagus  is  simple  and  cylindrical,  having  the  same 
width  as  the  lip-region,  and  is  separated  from  the  cardiac  bulb  by  a  broad  con- 
striction.    The  triquetrous  lining  of  the  oesophageal  tube  is  easily  seen,  and 
ends  in  a  distinct  manner  near  the  base  of  the  pharynx.     The  intestine  is  modi- 
fied, i.e.,  enlarged,  to  form  a  sort  of  "stomach,"  for  a  distance  equal  to  twice 
the  width  of  the  body;  thereafter  its  width  does  not  exceed  one-fourth  that  of 
the  body.     The  length  of  the  rectum  is  one  and  one-half  times  that  of  the  anal 
body-diameter,  and  it  has  the  peculiarity  of  lying  close  to  the  ventral  side  of  the 
body.     Region  of  the  ventral  excretory  pore  conspicuously  marked  by  a  large 
colorless  ampulla.     The  lateral  fields  are  one-third  as  wide  as  the  body.     The 
nerve-ring  encircles  the  oesophagus  squarely.     The  anterior  fourth  of  the  tail 
is  somewhat  hemispherical,  and  at  the  end  of  this  part  one-third  as  wide  as  at 
the  anus;  thence  onward  it  is  conical  to  the  acute  terminus.     The  large,  ele- 
vated, and  very  prominent  vulva  is  situated  far  forward,  somewhat  in  front  of 


PROTRELLUS,    COLPURELLA  257 

the  cardiac  bulb,  in  fact,  and  from  it  the  vagina  and  long  single  uterus  are  di- 
rected backward,  the  vagina  being  highly  muscular,  and  in  its  contracted  condi- 
tion thrice  as  long  as  the  body  is  wide.  The  uterus  ends  and  the  ovaries  begin 
near  the  commencement  of  the  posterior  third  of  the  body.  There  are  numerous 
fusiform,  slightly  curved  eggs,  measuring  50  X  104  microns,  the  shells  of  which 
acquire  a  bright  yellow  color  on  entering  the  uterus.  In  many  cases  these  golden- 
shelled  eggs  give  the  nemas,  when  seen  with  the  unaided  eye,  a  bright  yellow 
appearance.  The  ovaries  extend  forward,  then  backward  again;  the  ova  are 
arranged  single  file.  The  eggs  in  the  proximal  part  of  the  ovaries  and  in  the 
uterus  have  the  less-pointed  end  saddled  with  a  peculiar  organ.  The  saddled 
end  of  the  egg  is  directed  away  from  the  vulva. 

.8        10.          21.  «M  W.      _ 

z.~5  iTv  *~6  7.8~-f-TjT  '  "  On  the  very  much  smaller  male,  the  plain, 
transverse  striae  measure  3  microns  apart  on  the  neck,  and  2  microns  on  the 
body.  There  is  no  distinct  boundary  between  the  rounded  head  and  the  conoid 
neck.  The  lips  are  very  small  and  connate.  Small,  low,  refractive  papillae 
occur  near  the  margin  of  the  head.  The  somewhat  irregular  pharynx  is  half  as 
deep  as  the  head  is  wide,  and  about  two-thirds  as  wide  as  deep.  The  anterior 
three-fifths  of  the  oesophagus  is  a  tube  two-fifths  as  wide  as  the  middle  of  the 
neck,  the  remaining  two-fifths  being  flask-shaped,  the  neck  of  the  flask  being 
somewhat  narrower  than  the  anterior  tube,  and  the  ovoid  bulb  being  two-thirds 
as  wide  as  the  neck.  Cardiac  collum,  though  shallow,  distinct.  The  thin- 
walled  intestine  is  at  first  at  least  two-thirds  as  wide  as  the  body.  The  nerve- 
ring  encircles  the  oesophagus  squarely.  The  tail  diminishes  rapidly  behind  the 
anus,  until  only  one-third  as  wide  as  at  the  anus.  There  are  three  pairs  of  papil- 
lae, all  sub-ventral :— one  pair  of  conical  papillae,  the  largest  of  all,  just  in  front 
of  the  anus;  a  second  smaller  pair  somewhat  behind  the  anus;  and  a  third  pair 
near  the  middle  of  the  tail.  The  single  linear,  acute  spiculum  makes  an  angle 
of  45°  with  the  axis  of  the  body;  its  length  equal  to  that  of  the  narrow  part  of  the 
tail.  Testis-flexure  such  that  the  cardia  lies  half  way  between  it  and  the  nerve-ring. 
Habitat:  Rectum  of  the  cock-roach,  Polyzostaria  melanaria  Erich.,  Moss  Vale, 
New  South  Wales,  Australia,  August  17,  1894.  Examined  in  water. 

(.6)7.6      ».        *>.          '=*  98.       1(. 

39.  Colpurella  fontinalis  n.  sp.  UJ  l-9     "     2'2  Cuticle  thick, 

naked.  No  labial  papillae.  Pharynx  very  long  and  tubular. 
Neck  cylindroid  posteriorly.  The  oesophagus  is  at  first  three- 
fifths,  near  the  nerve-ring  two-fifths,  and  finally  two-thirds,  as 
wide  as  the  base  of  the  pharynx.  It  is  a  little  narrower  through 
the  middle,  so  that  one  may  detect  a  faint  posterior  swelling. 
No  cardia.  The  thick-walled  intestine,  which  has  a  faint 
lumen,  is  separated  from  the  oesophagus  by  a  collum  one-fourth 
as  wide  as  the  neck,  and  becomes  at  once  one-half  as  wide  as  the 
body.  Numerous,  minute,  uniform  granules  occur  in  the  cells  X  750 
of  the  intestine.  Renette  unknown.  Female  unknown.  Five 
somewhat  equidistant,  papillate  supplementary  organs,  one- 
third  as  high  as  the  cuticle  is  thick,  occupy  a  distance  equal  to 
two  and  one-half  times  the  length  of  the  body-diameter.  The 
posterior  supplement  is  near  the  proximal  part  of  the  spicula. 
The  organs  are  wider  apart  anteriorly.  Oblique  copulatory  IfOl. 
muscles  coextensive  with  the  supplements.  Exact  form  of  the  testes  unknown. 

Habitat:  Spring,  at  Country  Club,  Washington,  D.  C.,  U.  S.  A.  Sublimate  to 
balsam.  Fig.  39.  n,  designates  a  caudal  pocket,  and  not  the  anus,  which  is 
farther  forward. 


258  ORDER    ISOLAIMIA 


40.  Pycnolaimus  pygmaeus  n.  sp.   *•?      6-       TJ         7.7        4.9     '  "    Cuticle  thin 
naked.    Near  the  middle  of  the  body  the  very  narrow,  exceedingly  minutely 
crenate  wings  occupy  a  space  about  equal  to  the  width  of  two  annules  of  the 
cuticle.     Neck  conoid.     From  the  amphids  an  internal  element  extends  inward 
and  backward  a  distance  twice  as  great  as  the  width  of  the  corresponding  portion 
of  the  neck.    Lip-region  difficult  to  decipher.     Cephalic  cuticle  very  thick,  espe- 
cially near  the  base  of  the  lips.    When  the  head  is  viewed  in  profile  and  in  optical 
section  there  are  seen  connected  with  this  thickened  portion  of  the  labial  cuticle 
elements  that  extend  forward  over  the  vestibule.    At  first  sight  these  extensions 
appear  to  be  thin,  cutinized  flaps,  that  are  very  minutely  transversely  striated. 
A  careful  examination,  however,  appears  to  indicate  that  they  may  have  some- 
what the  structure  of  odontia,  inasmuch  as  a  short  distance  behind  the  apices, 
which  are  decidedly  sharp,  the  inner  contours  curve  in  toward  the  axis  of  the 
head,  and  the  longitudinal  section  of  the  elements,  including  the  bases,  above 
described,  appear  claw-shaped.    The  dorsal  and  ventral  elements,  thus  viewed, 
are  very  much  alike.     Concentrating  attention  on  either  lateral  surface  of  the 
head  one  finds,  opposite  the  axis,  two  elements  which  extend  forward  parallel 
to  each  other  and  then  bend  toward  the  axis,  arching  inward  to  meet  the  dorsal 
and  ventral  elements  already  described,  and  appear  to  be  the  median  elements 
of  lateral  labial  organs.    These  elements  are  not  so  finely  striated  as  the  labial 
elements  first  mentioned,   and  appear  to  be  slightly  darker.     The  napiform 
vestibule  leads  to  the  pharynx,  the  entrance  to  which  seems  to  be  nearly  closed 

mnd  by  a  very  slight  curvature  on  the  anterior  part  of  one  of  the  cutin- 
ous  elements  marking  its  contour.  The  oesophagus  diminishes 
,  .  slightly  in  diameter  as  it  passes  backward,  so  that  its  middle  part 
1  is  hardly  two-fifths  as  wide  as  the  corresponding  portion  of  the 
neck.  It  then  diminishes  more  rapidly,  so  that  just  in  front  of  the 
aw  Jw?S"*  cardiac  bulb  it  is  only  about  one-third  as  wide  as  the  corresponding 
spn  jfeJ  x75o  portion  of  the  neck.  There  is  no  vestige  of  a  median  bulb.  Cardiac 
bulb  somewhat  pear-shaped,  or  sub-spherical,  three-fifths  as  wide  as  the  base  of 
the  neck,  and  containing  a  rather  complex  central  valve  half  as  wide  as  the  bulb 
itself.  Two  small,  refractive  elements  occur  one  in  front  of  the  other  in  the  midst 
of  the  valve.  There  is  a  sub-spherical  cardia  one-third  as  wide  as  the  base  of 
the  neck.  The  intestine  becomes  at  once  three-fourths  as  wide  as  the  body; 
its  cross-section  presents  apparently  only  two  cells.  These  cells  contain  granules 
of  various  sizes  and  kinds;  the  largest  and  clearest  are  spherical,  and  have  a 
width  two  to  three  times  that  of  one  of  the  annules  of  the  cuticle.  The  smaller 
and  darker  granules  are  not  distinctly  spherical  and  vary  in  size  down  to  those 
of  very  minute  size.  From  the  inconspicuous  but  very  slightly  raised  anus,  the 
refractive  rectum  extends  inward  a  distance  a  little  greater  than  the  anal  body- 
diameter.  The  tail  is  conoid  from  the  anus,  but  is  convex-conoid  at  the  termi- 
nus. The  description  is  derived  from  a  specimen  much  too  young  to  give  any 
indication  as  to  the  position  and  form  of  the  sexual  organs.  The  measurements 
must  be  correspondingly  interpreted. 

Habitat:  From  green-house  soil,  Ann  Arbor,  Mich.,  U.  S.  A.     Fixed  in  Flem- 
ming;  examined  in  water.    Fig.  40. 

41.  Isolaimium  papillatum  n.  sp.    Cuticle  rather  thin,  naked.     Neck  convex- 
conoid  anteriorly.    Cuticle  with  surface  innervations  along  the  edges  of  the 
lateral  field.    Nerve-ring  oblique.    Pharynx  tubular,  one-sixth  as  wide  as  the 
head  measured  opposite  its  base.    Tail  of  the  male  conoid,  slightly  arcuate,  a 


ISOLAIMIUM,    COINONEMA  259 

little  longer  than  the  anal  body-diameter,  blunt,  its  ventral  contour  nearly 
straight,  its  dorsal  contour  arcuate.  The  rather  simple,  blunt,  uniform,  more  or 
.*•*.  A5 .  ."'.53!".  .9-.  3.9..  less  slender,  arcuate 
LZ  w''*  spicula  are  about  as 

.5-.2.  A6.  .  r*r.  .*•*    ,8     long  as  the  anal  body- 
diameter.     Their   non- 

cephalated  proximal  ends  lie  ventrad  from  the  body- 
axis.  The  frail,  slender,  arcuate  accessory  piece  is 
parallel  to  the  spicula  and  one-third  as  long;  at  its  prox- 
imal end  it  has  a  very  small,  backward-pointing  apoph- 
ysis  from  which  muscular  strands  pass  forward  to  the 
dorsally  submedian  lines  and  backward  to  the  ventral 
subait  field  near  the  middle  of  the  tail.  The  six  papilloid  or 
mammiform,  sub-equidistant  supplements  occupy  a 
X  750  space  about  three  times  as  great  as  the  anal  body-diam- 
eter. Each  comprises  about  six  annules  of  the  cuticle 

and  has  the  same  slightly  crenate  contour  as  the  ventral  surface.  The  tail  bears 
four  pairs  of  flattish,  conoid  papillae,  a  little  behind  its  middle;  one  dorsally 
submedian,  one  lateral,  one  ventrally  submedian  and  one  subventral. 

Habitat:  Soil,  Plummer's  Island,  Potomac  River,  Virginia,  U.  S.  A.    Flem- 
ming  to  glycerine  jelly.    Fig.  41. 

42.  Coinonema  punctatum  n.  sp.  Lips  thick.  Neck  conoid.  Eye-spots  two, 
far  apart,  brown  to  yellow,  solid,  with  backward  connections.  The  cylindroid 
oesophagus  is  at  first  one-half,  at  the  nerve-ring  one-third,  and  finally  also  one- 
third,  as  wide  as  the  corresponding  portion  of  the  neck ;  lining  subdistinct.  There 
is  a  cylindroid  cardia  one-fourth  as  wide  as  the  base  of  the  neck.  The  intestine, 
set  off  by  a  collum  one-fifth  as  wide  as  the  base  of  the  neck,  becomes  at  once 
three-fourths  as  wide  as  the  body.  Anteriorly  it  is  thick-walled,  posteriorly 
thin-walled.  Its  cross-section  is  composed  of  four  to  five  cells.  These  cells 
contain  numerous  granules  packed  together  in  such  a  way  as  to  give  rise  to  a 
faint  tessellation.  The  granules  are  of  variable  size,  the  largest  set  subm  \  Ib  /  ytqih 
being  one-tenth  to  one-sixteenthjas  wide  as  the  body.  The  anus 
is  continuous,  the  rectum  three-fourths  as  long  as  the  anal 
body-diameter.  The  conoid  tail  tapers  from  the  anus  to  the 
rather  minute  spinneret.  The  three,  broadly-saccate  caudal  pw  Lfe 
glands  lie  hi  a  close  tandem  in  the  anterior  third  of  the  tail.  '  ., 
The  ellipsoidal  renette  cell  stretches  along  behind  the  base  of  (f^llfe 
the  neck  for  a  distance  equal  to  1  9  M  »>52i«  87  jfe^lr^^t 

twice  the  width  of  the  body;  it  14; H     IT? M       aTT*1'  "    #/j  V//.' 

is  two-thirds  as  wide   as  long.  ^  13  5       _^      ^ 

From  the  continuous,  rather  i.2/  2.3  2.4  2.7"~^2.2?1- 
inconspicuous  vulva,  the  rather  weak,  non-cutinized,  medium-sized  vagina  leads 
inward  one-third  the  way  across  the  body.  The  eggs  occur  one  at  a  time  in  each 
uterus,  and  are  one  and  one-half  times  as  long  as  the  body  is  wide.  They  appear 
elongated  in  form  and  are  deposited  after  segmentation  begins.  In  the  medium- 
sized,  tapering  ovaries  are  ten  to  twelve  ova  arranged  single  file.  The  acute 
spicula  are  rather  frail  and  slender.  Their  proximal  ends  appear  to  lie  ventrad 
from  the  body-axis.  A  refractive  "chord"  appears  to  subtend  the  arc  of  the 
spicula.  The  rather  frail,  somewhat  slender,  arcuate  accessory  pieces  have  an 


260  ORDER    ISOLAIMIA 

applied  part  one-third  as  long  as  the  spicula,  and  projecting  at  right  angles  to 
this  is  a  uniform,  blunt  apophysis,  one-half  as  long  as  the  anal  body-diameter 
having  its  proximal  end  opposite  the  axis  of  the  tail.  The  testes  are  wide  and 
more  or  less  tapering. 

Habitat:  Key  West  and  Biscayne  Bay,  U.  S.  A.,  on  algae.  Flemming  to  glyc- 
erine jelly.  Fig.  42,  p.  259. 

43.  Rhynchonema  cinctum  n.  sp.    Annules  of  the  cuticle  retrorse  posteriorly, 
the  reverse  anteriorly.     Neck  cylindroid,  very  rapidly  narrowing  just  behind  the 
head,  and  thence  nearly  cylindroid,  so  that  the  entire  head 
qJlsetUOl  forms  a  kind  of  flexible  beak.     There  are  no  eye-spots.     Co- 
tstibcph  n°id  oesophagus  at  the  nerve-ring  two-fifths,  and  finally  one- 
half,  as  wide  as  the  corresponding  part  of  the  neck;  it  has  a 
("   fine  colorless  musculature  with  no  indication  of  glands.     The 
lining  is  indistinct.     There  is  no  cardia.     The  intestine,  set 
off  by  a  collum  one-fifth  as  wide  as  the  neck,  becomes  at  once 
three-fourths  as  wide  as  the  body.     It  has  a  distinct  refrac- 
5)  7  3     16      25.       '-72        89.  tive  lumen  and  is  thick-walled;  its  cross-section 

'(.8)'i.V  "i5':  "3-V  "  '3.4      '2:9  presents  two  to  three  cells.     From  the  continu- 

(.5)  7.4  16.  •  26.  *-M  87.  >  5  °us  anus,  the  rather  inconspicuous  though 
'(.9)  'i.V  '  3-3'  '3.'?'  '  '  j.j'f^M  cutinized  rectum  is  three-fourths  as  long  as  the 
anal  body-diameter.  Only  the  first  few  cells  of  the  intestine  show  granulation. 
The  conoid,  sub-arcuate  tail  tapers  from  the  anus  to  the  non-striated  spin- 
neret, whose  width  is  about  equal  to  that  of  three  of  the  caudal  annules.  At 
the  base  of  the  spinneret  there  are  always  about  three  minute  nuclei  that  stain 
strongly.  The  ellipsoidal  caudal  glands  form  a  close  tandem  in  the  anterior 
two-fifths  of  the  tail.  The  lateral  fields  are  about  one-third  as  wide  as  the 
body,  but  are  more  or  less  indistinct.  Renette  unknown.  In  the  vicinity 
of  the  vulva  about  eight  of  the  annules  present  simply  a  crenate,  instead  of 
a  serrate  contour.  The  broadly  elevated  vulva  is  rather  conspicuous,  particu- 
larly in  front.  Vagina  small.  A  mass  of  small  sperm  cells  has  been  noted  near 
the  vulva.  The  eggs  are  about  eight  times  as  long  as  the  body  is  wide  and  one- 
twelfth  as  wide  as  long.  They  are  granular  ^and  have  a  prominent  central 
nucleus.  The  narrow  cylindroid  ovaries  contain  ova  arranged  single  file.  The 
spicula  of  the  male,  about  as  wide  as  one  of  the  adjacent  annules,  are  slender, 
rather  frail,  and  sub-acute,  and  when  seen  in  profile  appear  to  have  their  proxi- 
mal ends  about  opposite,  or  a  little  dorsad  from,  the  body-axis.  There  is  a 
slender,  frail  accessory  piece.  The  three  minute  papilloid  supplementary  organs 
occupy  a  space  three  times  as  great  as  the  body-diameter,  and  are  about  one 
body-width  apart;  the  posterior  member  is  about  two  body-widths  in  front  of 
the  anus.  They  hardly  more  than  accentuate  the  annules  on  which  they  occur, 
but  are  rendered  visible  by  carmine  stains.  The  ejaculatory  duct  is  one-fourth 
as  wide  as  the  corresponding  portion  of  the  body,  the  cylindroid  testis  one-half 
as  wide. 

Habitat:  Salaverry,  Peru,  near  low  tide  mark;  marine.  Rhynchonema  is  com- 
posed of  a  considerable  number  of  species  occurring  in  at  least  the  Atlantic  and 
Pacific  Oceans.  With  low  powers  it  is  difficult  to  distinguish  the  head  end  from 
the  tail  end.  The  flexible,  narrow  head  suggests  the  functions  of  a  beak.  One 
may  imagine  it  to  probe  the  depths  of  some  receptacle  containing  food,  for 
instance  the  neck  of  an  algal  oogonium.  However,  nothing  is  known  with  cer- 
tainty concerning  the  food  habits.  Fig.  43. 


LAIMELLA,    ILLIUM 


261 


1.3        5-4        9.2      "-3?-".  .  .70..  .    1 

44.  Laimella  longicauda  n.  sp  Li"  'i.j/  '  to  .....  i*  1-7  '  "  Striae  difficult  to 
detect,  but  resolvable  into  almost  invisible  dots.  Cuticle  naked.  Labial  papil- 
lae obscure.  Pharynx  closed,  inconspicuous,  but  undoubtedly  present.  There 
is  a  slight  thickening  or  extra-refractiveness  at  one  portion  of  the  pharyngeal 
wall  that  suggests  the  presence  of  an  extremely  minute  onchium.  The  cylindroid 
oesophagus  near  the  nerve-ring  is  two-fifths  as  wide  as  the  neck,  and  ends  in  an 
ellipsoidal  valveless  bulb  three-fourths  as  wide  as  the  base  of  the  neck.  The 
oesophagus  has  a  fine  colorless  musculature.  Hemispherical  cardia,  two-sevenths 
as  wide  as  the  base  of  the  neck.  The  thick-walled  intes- 
tine,  set  off  by  a  cardiac  collum  one-fifth  as  wide  as  the 
neck,  becomes  gradually  five-sixths  as  wide  as  the  body, 
its  cross-section  presenting  about  six  cells.  From  the 
somewhat  depressed  anus,  the  rather  prominent  cutin- 
ized  rectum  extends  inward  a  distance  equal  to  the  anal 
body-diameter.  The  colorless,  scattered  to  numerous 
intestinal  granules  are  of  variable  size,  the  largest  of 
them  at  first  only  twice  as  wide  as  one  of  the  annules,  but 
near  the  middle  of  the  body  six  to  eight  times  as  wide. 
Tail  setaceous,  but  conoid  for  a  distance  six  times  as 
great  as  the  anal  body-diameter,  at  which  distance  it  is  one-fifth  as  wide  as  at 
the  base;  thence  it  tapers  very  gradually  to  the  terminus.  It  is  very  doubtful 
if  there  is  a  spinneret.  There  are  elements  in  the  base  of  the  tail,  simulating 
caudal  glands,  but  no  definite  ducts  have  been  seen,  and  the  terminus  seems 
too  fine  to  afford  space  for  a  spinneret.  About  six  very  slender  caudal  setae, 
each  about  two-thirds  as  long  as  the  anal  body-diameter,  occur  on  each  of  the 
four  submedian  lines.  Similar  setae  occur  throughout  the  body.  The  lateral 
fields  are  two-fifths  as  wide  as  the  body.  The  large,  non-granular,  elongated 
renette  cell  lies  just  behind  the  base  of  the  neck,  and  empties  through  an  ellip- 
soidal ampulla,  one-third  as  wide  as  the  neck.  The  broad,  oblique  nerve-ring 
is  accompanied  by  rather  obscure  nerve  cells.  From  the  small,  more  or  less 
continuous  vulva,  the  moderate-sized,  conoid,  cutinized  vagina  extends  three- 
fifths  the  distance  across  the  body.  The  elongated  eggs  are  one  to  one  and  one- 
half  times  as  long  as  the  body  is  wide.  The  ellipsoidal  sperm  cells  in  the  uterus 
are  granular  and  about  half  as  long  as  the  body  is  wide.  The  cylindroid  ovaries 
contain  at  least  ten  ova,  arranged  single  file. 

Habitat:  Algae,  Key  West;  also  mud-flat,  Biscayne  Bay,  Florida,  U.  S.  A. 
Flemming  to  glycerine  jelly.     Fig.  44.     Terminus,  trm,  shown  foreshortened. 


*  750 


45.  Illium  exile  n.  sp.  -4  -^  i-  1-1  .e>2'5"  Cuticle  naked.  Neck  co- 
noid. Oesophagus  conoid,  finally  about  three-fourths  as  wide  as  the  base  of  the 
neck.  Cardia  elongated,  half  as  wide  as  the  base  of  the  neck.  The  intestine 
amoh  \arna  becomes  at  once  about  two-thirds  to  three-fourths  as 
I  \  wide  as  the  body.  Its  cross-section  appears  to  be 


\j/spn  made  up  of  about  six  cells.  The  posterior  lip  of  the 
anus  is  slightly  elevated.  From  it  there  extends 
inward  the  rather  strongly  cutinized  rectum,  which 

is  about  as  long  as  the  anal  body-diameter.  The  lateral  fields  are  a  little  more 
than  one-third  as  wide  as  the  body.  The  ventral  gland  is  a  much  elongated 
cell,  lying  at  a  distance  behind  the  base  of  the  neck  equal  to  about  three  to  four 
body-diameters,  and  having  a  width  about  one-fourth  as  great  as  that  of  the 
corresponding  portion  of  the  body.  There  is  a  distinct  ellipsoidal  ampulla 


262 


ORDER   ISOLAIMIA 


one-third  as  wide  as  the  middle  of  the  neck,  connected  with  the  excretory  pore 
by  a  short,  rather  sharply  curved,  minute  duct.  The  caudal  glands  are  located 
in  a  tandem  series  a  considerable  distance  in  front  of  the  anus,  that  which  is 
farthest  forward  being  somewhat  farther  from  the  anus  than  is  the  spinneret. 
The  tail  is  conoid  in  the  anterior  three-fifths  in  such  a  fashion  that  at  the  begin- 
ning of  the  fourth  fifth  it  has  a  diameter  about  one-fourth  as  great  as  at  the  anus; 
thence  onward  the  tail  is  cylindroid  to  the  terminus  which  bears  a  slightly  oblique 
spinneret.  From  the  inconspicuous  vulva  the  rather  strongly  cutinized  vagina 
leads  inward  more  than  half  way  across  the  body.  The  ovaries  reach  about  two- 
thirds  the  distance  back  to  the  vulva,  at  any  rate  in  the  only  specimen  so  far 
examined,  which  was  a  rather  immature  female.  Nothing  is  known  concerning 
the  number,  size  and  structure  of  the  eggs. 
Habitat:  Green  algae,  Carlisle  Bay,  Jamaica.  Fig.  45,  p.  261. 


46.  Cynura  uniformis  n.  sp.  '9 


"  The  rather  thick  cuticle 


is  naked.  The  two  wings,  occupying  a  space  one-third  as  wide  as  the  body, 
begin  near  the  head  and  end  on  the  tail.  Pharynx  very  strongly  reminiscent 
of  that  of  Plectus; — is  continued  by  a  longer  posterior 
part,  whose  presence  is  indicated  mainly  by  alterations 
in  the  lining.  This  part,  however,  is  rather  easily  dis- 
tinguished  from  the  oesophagus  proper.  Neck  cylin- 
droid  posteriorly,  convex-conoid  anteriorly.  The  cylin- 
droid oesophagus  near  the  nerve-ring  is  three-sevenths, 
finally  three-fifths,  as  wide  as  the  corresponding 
portion  of  the  neck.  The  radial  oesophageal  tissue  con- 
.  I  i\i\\  tinues  to  the  middle  of  the  anterior  chamber  of  the 
pharynx,  but  is  narrower  there.  There  is  the  faintest 

/.' ;;  £feIHi  5g2sL  lV  possible  break  in  the  lining  of  the  oesophagus  near  the 
oe  nerve-ring, — possibly  the  vestige  of  a  bulb.  There  is  a 
large  cylindroid  cardia,  three-fifths  as  wide  as  the  neck. 
The  thick-walled  intestine  becomes  at  once  two-thirds 
as  wide  as  the  body;  while  its  lumen  is  faint  anteriorly, 
it  is  very  pronounced  posteriorly.  From  the  elevated 
anus,  the  strongly-built,  prominent  rectum, — the  lining 
of  which  is  somewhat  cutinized, — extends  a  distance 
three-fourths  as  great  as  the  anal  body-diameter.  The 
cells  of  the  intestine  are  packed  with  granules  of  variable 
size,  the  largest  of  which  have  a  width  equal  to  that  of 
X  750  one  of  the  annules.  The  tail  is  cylindroid,  then  conoid 
in  the  posterior  three-sevenths.  The  blunt,  conoid  terminus  is  strengthened  by 
a  large,  obliquely-truncate  cap,  the  several  component  plates  of  which  are  mi- 
nutely punctate.  The  caudal  glands  probably  lie  in  front  of  the  anus;  they  end 
in  the  terminus  in  three  simple,  prominent  ampullae.  There  are  no  caudal  setae. 
The  lateral  fields  appear  to  be  about  one-third  as  wide  as  the  body.  The  granular 
ellipsoidal  renette  cell,  two-thirds  as  long  as  the  body  is  wide,  and  half  as  wide 
as  long,  lies  about  two  body-widths  behind  the  base  of  the  neck.  The  medium- 
sized  nerve-ring  is  accompanied  by  obscure  nerve  cells.  From  the  medium- 
sized,  more  or  less  elevated,  refractive  and  therefore  conspicuous  vulva,  the 
vagina  leads  inward  half  way  across  the  body.  The  inner  wall  of  the  vagina 
is  also  cutinized.  The  short,  broad,  cylindroid  ovaries  contain  about  fifteen 
ova  arranged  somewhat  irregularly.  Ellipsoidal  granular  spermatozoa,  seen  in 
the  uteri,  are  one-eighth  to  one-tenth  as  wide  as  the  body  of  the  female. 


CYNURA,   XINEMA 


263 


Habitat:  Seaweed,  washed  up  at  Ocean  Beach,  Miami,  Fla.,  U.  S.  A.,  after  a 
storm.  Flemming  to  glycerine  jelly.  Only  a  single  specimen  seen.  Fig.  46,  p.  262. 

47.  Xinema  perfectum  n.  sp.  Neck  conoid.  Somatic  setae  papilloid,  or  nearly 
so;  cuticle  becoming  much  thinner  in  the  region  of  the  lateral  organs,  thickening 
again  in  front  of  them  and  becoming  again  as  thick  as  ever  on  the  front  of  the 
head.  The  oesophagus  continues  to  have  the  same  diameter  until  after  it  passes 
through  the  nerve-ring,  when  it  begins  to  expand  gradually,  until  finally  it  is 
nearly  three-fourths  as  wide  as  the  base  of  the  neck.  The  two  ventrally  sub- 
median  sectors  of  the  oesophagus  appear  to  contain  glands,— at  least  in  each  there 
extends  from  near  the  posterior  end  of  the  oesophagus  forward  a  minute  duct, 
which  stains  distinctly  with  carmine.  This  duct  can  be  traced  at  least  as  far 
as  the  nerve-  .4  .4.5  :  8.7  "-&-"  94.3y23 

ring.  There  does  "«""»•>''""»•"« ».s Of*  ' 

not  appear  to  be  .3      4.4.    s.s>        -M-"     94.  ^24 

any  very  distinct  W*"xi/"»:i i'.ir^U 

cardia.  The  intestine  gradually  becomes  three- 
fourths  as  wide  as  the  body.  In  cross-section 
it  is  composed  of  six  to  eight  cells,  containing 
relatively  large  nuclei  and  numerous  small,  uni- 
form granules.  The  renette  cell,  nearly  as  long 
as  the  body  is  wide  and  about  one-third  as  wide  #" 
as  long,  is  located  just  behind  the  base  of  the  neck.  Its  ampulla,  about  one- 
fourth  as  wide  as  the  corresponding  portion  of  the  neck,  is  connected  with  the 
excretory  pore  by  means  of  a  very  short  duct.  The  lateral  fields  are  about  one- 
third  as  wide  as  the  body.  The  nerve-ring  surrounds  the  oesophagus  squarely. 
The  tail  tapers  from  considerably  in  front  of  the  anus,  being  convex-conoid  in 
such  a  fashion  that  at  the  beginning  of  the  final  fifth  it  has  a  diameter  about 
one-fifth  as  great  as  at  the  anus,  or  even  less;  thence  onward,  the  tail  expands 
a  little.  The  caudal  glands  are  located  near  the  anus.  From  the  depressed 
vulva,  the  vagina  leads  inward  more  than  half  way  across  the  body,  where  it 
joins  the  two  symmetrically-placed  uteri;  its  internal  walls  are  distinctly  cutin- 
ized.  The  ovaries  contain  twelve  to  fifteen  ova  arranged  single  file.  Occasion- 
ally the  tips  of  the  ovaries  are  reflexed.  Apparently  the  females  possess  a  pair  of 
spermatheca,  which  when  filled  reach  to  near  the  bases  of  the  ovaries.  The  sper- 
matozoa appear  to  be  elongated.  The  elongated  eggs  are  about  twice  as  long 
as  the  body  is  wide  and  a  little  less  than  half  as  wide  as  long;  they  have  been 
seen  in  the  uteri  one  at  a  time.  Tail  of  the  male  a  little  more  bulky  than  that  of 
the  female  and  a  little  narrower  in  the  posterior  part,  which  instead  of  constitut- 
ing one-fourth  of  the  tail,  constitutes  about  one-third.  No  supplements  or 
special  setae.  Spicula  consisting  of  two,  equal  segments,  one  in  front  of  the 
other.  The  muscular  tunic  enclosing  the  spicula  is  continuous  at  the  elbow. 
While  the  spicula  and  their  sheaths  tend  to  stain  in  acid  carmine,  the  accessory 
pieces  do  not  do  so,  but  retain  a  slight  yellowish  color  of  their  own.  The  caudal 
glands  are  located  alongside  the  accessory  pieces,  both  in  front  of  the  anus  and 
behind  it.  The  ejaculatory  duct  is  about  one-fourth  as  wide  as  the  body,  the 
vas  deferens  about  one-third. 

Habitat:  Marine  mud,  San  Pedro,  California,  U.  S.  A.  Specimens  of  this 
species  appear  to  have  a  tendency,  when  killed  with  hot  sublimate,  to  twist  and 
present  a  dorsoventral  view  of  the  head  instead  of  a  lateral.  Fig.  47. 


264  ORDER    ISOLAIM1A 

.•?.  ..S-Jrr  .«.-... 1.1'*'!'... 9-.  .>!.!.. 

48.  Ceramonema  attenuatum  n.  sp.  l-      2-4      2-8         3-         1>9  Each  annule 
of  the  thick,  transparent,  naked  cuticle  is  made  up  of  eight  elements  so  fitted 
together  as  to  be  reminiscent  of  the  arrangement  of  corrugated  roof-tiles;  hence, 
the  name  "Ceramonema"   (see  an,  Fig.  48).     Neck  cylindroid,  with  minute, 
somewhat  forward-pointing  setae  one-fourth  as  long  as  the  annules  are  wide. 
The  setae  occur  in  longitudinal  rows,  one  on  each  annule,  but  whether  on  each 
of  the  longitudinal  lines  is  problematical.     Lips  amalgamated.     It  is  probable 
that  there  are  minute  papillae  a  little  in  front  of  the  anterior  row  of  cephalic 
setae.     The  very  narrow  pharynx  joins  the  oesophageal  lumen  with  little  alter- 
ation.   The  oesophagus  gradually  narrows  to  near  its  posterior  part,  becoming  at 
its  narrowest  point  about  one-fourth  as  wide  as  the  neck;  thence  onward,  how- 
ever, it  expands  so  that  where  it  joins  the  intestine  it  is  about  half  as  wide  as  the 
base   of  the  neck.     There   is  no   distinct   cardia.     The  thin-walled   intestine 
becomes  at  once  two-thirds  as  wide  as  the  body.     Possibly  its  cross-section  is 

v>t  rnh  Ifil          f  Ih  comPosed  of  as  few  as  three  or  four  cells.     Anus 

inconspicuous;  rectum  fully  twice  as  long  as  anal 
$  body-diameter.  Salivary  glands  unknown.  The 
renette  appears  to  be  a  unicellular  gland  located 
fflpfi  immediately  behind  the  cardiac  constriction ;  it  is 
about  half  as  long  as  the  body  is  wide,  and,  as  usual, 
~y  tapers  anteriorly  to  join  the  narrow  excretory  tube. 
The  excretory  pore  is  perhaps  just  to  the  rear  of  the 
wph  nerve-ring-  ^  is  very  difficult  to  observe  the  longi- 
tudinal  fields,  owing  to  the  highly  refractive  nature 
of  the  elements  composing  the  cuticle.  These  latter 
join  each  other  in  such  fashion  as  to  give  rise  to  eight 
longitudinal  lines,  two  of  which  are,  of  course,  sub- 
lateral  and  span  a  distance  equal  to  about  one-third 
the  width  of  the  body.  The  nerve-ring  surrounds 
the  oesophagus  near  where  it  is  narrowest.  Tail 
conoid;  terminus  having  a  diameter  about  half  as  great  as  that  of  the  base  of 
the  tail.  The  final  caudal  segment  of  the  cuticle  is  more  than  twice  as  long  as 
the  penultimate,  though  it  seems  also  to  be  compound  in  its  structure.  The 
caudal  glands  appear  to  be  located  in  front  of  the  anus,  near  the  place  where  the 
intestine  joins  the  rectum.  From  the  depressed  and  inconspicuous  vulva  the 
vagina  leads  inward  nearly  half  way  across  the  body.  The  reflexed  portions  of 
the  ovaries  reach  well  back  toward  the  vulva.  The  eggs  are  long  and  narrow, 
though  no  specimens  have  been  seen  containing  well-matured  eggs. 

Habitat:  Mud  among  marine  algae,  shores  of  Kingston  Harbor,  Jamaica.  Sub- 
limate to  balsam.  The  male  of  another  undescribed  species  has  stoutish,  taper- 
ing, subacute,  rather  frail  spicula,  accompanied  by  a  more  or  less  arcuate,  rather 
slender,  frail,  simple  accessory  piece  half  as  long.  There  are  no  supplementary 
organs.  This  undescribed  species  is  so  similar  to  C.  attenuatum  that  it  is  believed 
the  male  of  attenuatum  will  be  found  to  present  similar  features.  Fig.  48. 

.4        4.8   .     7.8        "<4<>1S       92. 

49.  Bolbonema  brevicolle  n.  sp.       i-*' '  '*•$'•' '«         V?       U*  1'3"  Neck  conoid. 
The  walls  of  the  pharynx  are  a  little  more  strongly  cutinized  than  those  of  the 
oesophagus,    especially   toward   the   minute   mouth   opening.     The   cylindroid 
oesophagus  is  about  three-fifths  as  wide  as  the  base  of  the  head,  but  expands 
finally  to  form  the  pyriform  cardiac  bulb,  which  is  about  four-fifths  as  wide 
as  the  base  of  the  neck.     This  bulb  has  no  distinct  valve,  though  the  cutinous 


BOLBONEMA,    OMICHONEMA  265 

lining  is  more  strongly  developed  in  the  bulb  than  it  is  elsewhere.  There  appears 
to  be  an  elongated  cardia,— perhaps  one-third  as  long  as  the  neck  is  wide.  The 
intestine  begins  as  a  narrow  tube  only  about  one-fourth  as  wide  as  the  base  of  the 
neck,  and  enlarges  gradually  so  that  near  the  middle  of  the  nema  it  is  about  one- 
half  as  wide  as  the  corresponding  portion  of  the  body.  For  a  distance  behind 
the  bulb  as  great  as  the  body-diameter,  the  cells  of  the  set  (4) 
intestine  contain  nuclei  which  stain  more  strongly  with 
carmine  than  do  their  neighbors.  Thence  onward  the 
cells  contain  granules  of  variable  size,  the  largest  being 
larger  than  any  of  the  nuclei  in  any  of  the  adjacent  , 
cells.  The  intestine  shows  about  four  cells  in  cross-  "'.. 
section;  their  contents  are  so  disposed  that  there  is  .a  \jjl 
distinct  tessellated  effect.  Anus  slightly  raised;  the -?»Hy  :^:=:rg3\  X750 
rectum  as  long  as  the  anal  body-diameter.  There  appears  to  be  no  doubt  about 
the  existence  of  a  unicellular  renette  cell  just  behind  the  neck,  but  the  position 
of  the  excretory  pore  is  unknown.  Lateral  fields  about  one-third  as  wide  as  the 
body.  Tail  conoid.  From  the  slightly  raised  vulva,  the  vagina  leads  inward 
fully  one-third  the  distance  across  the  body.  The  eggs  appear  to  occur  one  at  a 
time  in  each  uterus.  They  are  fully  twice  as  long  as  the  body  is  wide,  and  con- 
siderably less  than  half  as  wide  as  long.  It  seems  probable  that  segmentation 
sets  in  before  the  eggs  are  deposited. 

Habitat:  Mud,  shallows  of  Kingston  harbor,  Jamaica.     Sublimate  to  balsam. 
Fig.  49. 

1.1        8.8  .    19- -85. «•_ 

50.  Omicronema  litorium  n.  sp.  1.5  "*.  :  i-9  *-i  1-6  "  "  Cuticle  rather 
thin,  naked,  its  striae  more  easily  resolvable  into  rows  of  longitudinal  markings 
near  the  extremities.  Wings  faint.  No  labial  papillae.  Amphids  yellowish. 
Oesophagus  at  the  nerve-ring  one-half  as  wide  as  the  middle  of  the  neck;  there- 
after it  expands  somewhat,  so  that  finally  it  is  about  two-thirds  as  wide  as  the  base 
of  the  neck.  The  oesophagus  has  a  somewhat  wavy  lining.  There  is  a  narrow, 
elongated  cardia,  nearly  half  as  long  as  the  body  is  wide.  The  intestine,  set  off 
by  a  deep  and  broad  constriction,  becomes  at  once  about  three-fourths  as  wide 
as  the  body.  The  lateral  fields  appear  to  be  about  one-fourth  as  wide  as  the  body. 
The  female  has  a  single  outstretched  ovary  extending  forward.  From  the  more  or 
less  conspicuous,  depressed  vulva,  the  rather  weak,  more  or  less  cutinized  vagina 
connects  with  the  straight  uterus,  which  contains  elongated  eggs,  twice  as  long 
as  the  body  is  wide  and  about  one-eighth  as  wide  as  long.  The  narrow  ovary  is 
first  cylindroid,  then  tapering.  The  larger  ova  are  arranged  single  file;  toward 
the  blind  end,  however,  the  ova  are  arranged  irregularly. 
The  conoid,  arcuate  tail  tapers  from  the  anus,  or  from  / 
somewhat  in  front  of  it.  The  three  ellipsoidal  caudal  ph  ..^jflf^-  Ml/r^ 
glands  lie  in  a  loose  tandem  in  the  anterior  half  of  the  tail. 


M      1.5-1.7         1.7  -11  i.T  The  tail  of  the  male  is   W 

arcuate  and  conoid  to  the  spinneret,  which  is  one-sixth 
as  wide  as  the  base  of  the  tail.  No  supplements,  though 
there  are  inconspicuous  setae  on  the  submedian  lines,  both  behind  and  in  front 
of  the  anus.  The  dark  rather  slender  spicula  attain  their  greatest  width  at 
their  bent  middle  parts.  Accessory  piece  nearly  as  long  as  the  anal  body- 
diameter.  Near  the  bends  of  the  spicula  the  accessory  piece  takes  on  a  sigmoid 
contour,  and  this  portion  is  connected  with  the  body  wall  both  anteriorly  and 
posteriorly  by  strands  of  muscle.  The  ejaculatory  duct  is  about  one-third  as 
wide  as  the  body. 


266  ORDER   ISOLAIMIA 

Habitat:  Ocean  beach-sand,  vicinity  of  Los  Angeles,  Calif.,  U.  S.  A.,  near  loi 
tide  mark.    Fig.  50,  p.  265. 

1.  6.          14.  18-"        66. 

51.  Halanonchus  macrurus  n.  sp.  *•  *•-  i-9  2.1  i. 
cuticle  is  very  finely  and  somewhat  irregularly  reticulated  upon  the  head.  Outer 
row  of  cephalic  setae  stout,  two-jointed.  Lips  probably  distinct  and  six  in  num- 
ber, thin,  flap-like.  Pharynx  somewhat  deeper  than  the  base  of  the  head  is  wide. 
The  pharynx  has  a  faint  triquetrous  framework,  the  three,  slender,  longitudinal 
elements  of  which  are  split  behind  (and  also  less  conspicuously  in  front),  the 

.,*,.  •••<_;,  tfttfi)  branches  thus  made  bowing  round  together;  this  imparts 

W  to  the  wall  of  the  pharynx,  opposite  the  beginning  of  the 
P°sterior  fourth>  a  junction-like  effect.  As  a  whole  the 
pharynx  is  much  like  an  elongated  and  naked  and  weakened 
Oncholaimus  pharynx  destitute  of  onchia.  The  cylindroid 
•  ™  to  conoid  oesophagus  near  the  nerve-ring  is  three-fifths, 
and  finally  two-thirds,  as  wide  as  the  neck.  The  distinct 
refractive  lining  appears  to  be  composed  of  two  to  three 
faint  elements,  occupying  a  space  three-fifths  as  wide  as 
the  oesophagus;  the  musculature  is  coarse.  Probably 
glands  are  present  in  the  oesophageal  tissues.  There  is  a 
X  750  more  or  less  hemispherical  cardia,  one-third  as  wide  as  the 
neck.  The  thick-walled  intestine  is  set  off  by  a  constriction  one-third  as  wide 
as  the  base  of  the  neck,  and  becomes  at  once  two-thirds  as  wide  as  the  body.  In 
cross-section  it  is  composed  of  about  twelve  cells.  The  rather  inconspicuous 
rectum  is  as  long  as  the  anal  body-diameter.  The  cells  of  the  intestine  contain 
scattered,  colorless  granules,  of  variable  size,  the  largest  of  which  are  one-twen- 
tieth as  wide  as  the  body.  The  larger  granules  darken  in  Flemming's  solution. 
The  tail  is  first  conoid,  and  then  cylindroid  in  the  posterior  two-thirds,  where 
it  is  one-third  as  wide  as  at  the  base.  It  tapers  from  in  front  of  the  anus  to  the 
terminus,  which  is  apparently  devoid  of  spinneret.  The  lateral  fields  are  three- 
fifths  as  wide  as  the  body;  their  margins  are  rather  distinctly  indicated  by  the 
abrupt  beginning  of  the  longitudinal  musculature.  Renette  unknown.  Nerve- 
ring  accompanied  by  obscure  nerve  cells.  From  the  large,  conspicuous,  some- 
what elevated  vulva  the  large,  tubular  to  conoid,  non-cutinized  vagina  extends 
obliquely  backward  a  distance  equal  to  the  body-diameter.  The  uterus  is  twice 
as  long  as  the  body  is  wide,  and  contains  four  to  seven  eggs,  which  are  probably 
deposited  after  segmentation  begins.  The  narrow  ovary  tapers  but  little,  and 
contains  about  thirty  ova  arranged  single  file.  The  sub-arcuate,  rather  simple, 
frail,  blunt  spicula  are  one-eighth  as  wide  as  the  body;  viewed  in  profile  their 
non-cephalated  proximal  ends  appear  to  lie  dorsad  from  the  body-axis.  The 
single,  more  or  less  straight,  very  slender,  frail,  simple,  parallel  accessory  piece 
is  one-third  as  long  as  the  spicula.  The  fifteen  to  eighteen  very  inconspicuous, 
sub-equidistant,  papilloid,  ventral  supplementary  organs  occupy  a  space  in  front 
of  the  anus  seven  times  as  long  as  the  body-diameter;  the  posterior  one  lies 
opposite  the  middle  of  the  spicula.  The  distance  between  these  organs  is  about 
one-fourth  of  one  body-diameter.  For  each  supplement  there  is  a  "pore"  in 
the  cuticle,  and  to  this  comes  a  "nerve-ending"  that  appears  to  project  more  or 
less.  The  sperm  cells  are  long  and  cylindroid. 

Habitat:  Sand  inside  government  cut,  Biscayne  Bay,  Florida,  U.  S.  A.     Flem- 
ming  to  glycerine  jelly.    Fig.  51. 


HALINEMA 


267 


52.  Halinema  spinosum  n.  sp.  There  are  a  few,  very  inconspicuous  cervical 
setae,  one-third  as  long  as  the  neck  iswide.  Cephalic  setae  three-jointed  (Fig. 
1,  2,  3).  Lips  three,  possibly  double.  Neck  more  or  less  cylindroid.  Oesophagus 
cylindroid,  with  an  almost  imperceptible  cardiac  swelling;— at  the  nerve-ring 
four-sevenths,  and  finally  three-fourths  as  wide  as  the  corresponding  portion  of 
the  neck.  The  sub-distinct  lining  of  the  oesophagus  is  optically  expressed  by 
refractive  lines  occupying  a  space  two-sevenths  as  wide  as  the  organ  itself.  The 
colorless  musculature  is  rather  coarse.  No  cardia  has  been  noted,  but  the  intestine 
is  at  first  more  refractive  in  its  lining,  and  otherwise  altered.  The  thick  walled 
intestine  is  set  off  by  a  collum  one-fourth  as  wide  as  the  neck,  and  has  a  faint, 
but  somewhat  refractive  lining.  It  soon  becomes  two-thirds  as  wide  as  the  body, 
and  in  cross-section  is  composed  of  few  cells.  From  the  anus,  the  posterior  lip 
of  which  is  elevated,  the  rather  inconspicuous  rectum  leads  inward  a  distance 
three-fourths  as  long  as  the  anal  body  diameter.  The  intestinal  cells  contain 
scattered  granules  of  variable  size,  the  largest  of  which  are  about  one-tenth  as 
wide  as  the  body;  they  darken  on  treatment  with  Flemming's  solution,  and  are 
strongly  refractive  in  glycerine  jelly.  The  conoid  tail  tapers  from  the  anus. 
The  broadly  saccate  caudal  glands,  three  in  number  and  relatively  small,  form 
a  close  tandem  in  the  anterior  eighth  of  the  tail.  The  posterior  half  of  the  tail 
bears  eight  pairs  of  ventrally  submedian  stiff  setae.  The  rather  fusiform,  non- 
granular  renette  cell  lies  on  the  ventral  side  of  the  body  a  little  behind  the  base 
of  the  neck;  it  empties  through  a  rather  conspicuous  ampulla  one-third  to  one- 
fourth  as  wide  as  the  corresponding  portion  of  the  neck.  The  nerve-ring  is  of 
medium  size  and  .7  3.2  6.8  "_5?.>  ?3  ^^ 
is  accompanied  *•  J-V  i-3  i-''  '  "i.  ' 
by  obscure  nerve  .4  2.3  4.3  -H-<"  90.  ?26 
cells.  The  fe-  '8  '  V  V  '  '  '"'**" 
male  sexual  apparatus  presents  a  vestigial  pos- 
terior branch.  Vulva  rather  large,  somewhat 
elevated;  vagina  more  or  less  cutinized.  The 
eggs  are  five  times  as  long  as  the  body  is  wide, 
and  evidently  occur  in  the  uterus  one  at  a  time. 
The  narrow  tapering  ovaries  contain  few  ova 
arranged  single  file.  The  spicula  are  rather 
strong,  somewhat  slender,  tapering  and  acute. 
Their  expanded  proximal  ends  appear  to  lie  ven- 
trad  from  the  body-axis.  The  applied  parts  of  j^ 
the  two  rather  frail  accessory  pieces  are  one- 
fourth  as  long  as  the  spicula.  They  have  taper- 
ing apophyses,  one-third  as  long  as  the  anal 

body  diameter,  whose  proximal  ends  lie  ventrad  from  the  body-axis.  Papilloid 
sub-equidistant  supplementary  organs  on  the  ventral  line  occupy  a  space  five  to 
six  times  as  long  as  the  body  diameter,  the  distance  between  them  being  about 
equal  to  three-fourths  the  corresponding  body  diameter.  Of  these  almost  imper- 
ceptible innervations,  the  posterior  one  lies  opposite  the  distal  portions  of  the 
spicula.  Ejaculatory  duct  two-fifths  as  wide  as  the  body.  There  seem  to  be 
two  narrow,  tapering  testes,  but  there  is  a  little  uncertainty  about  the  posterior 
one. 

Habitat:  Sand  bar,  opposite  the  mouth  of  the  Miami  River,  Biscayne  Bay, 
Florida,  U.  S.  A.     Flemming  to  glycerine  jelly.     Fig.  52. 


268 


ORDER   ISOLAIMIA 


4.8      10.2....  16.«         "-54-"        86.  g  __ 

53a.  Pseudolella  cephalata  n.  sp.  !>8  i*""  5j  '3.V  2.7  ''  "  Cuticle  naked; 
wings  optically  expressed  in  the  form  of  closely  approximated,  indistinct  longi- 
tudinal lines.  The  unusually  long  amphids  are  of  such  a  character  as  to  be 
mistaken  at  first  for  wings.  Behind  the  neck  the  amphids  gradually  narrow,  so 
that  somewhat  in  front  of  the  middle  of  the  body,  where  they  end,  their  width 
is  only  about  one-third  as  great  as  opposite  the  base  of  the  pharynx.  Neck 
conoid.  Cuticula  much  thinner  on  the  head.  Lips  thick  ;  six,  or  three  and  two- 


SSt(J)h(4) 


parted.  Internally  the  lips  are  armed  with  six  very  minute 
odontia  (?),  apparently  having  an  outward  stroke.  From 
the  expanded  base  of  the  pharynx  muscular  fibres  are  seen 
passing  to  the  front,  clearly  indicating  that  the  entire  struc- 
ture can  be  moved  forward;  such  movement  would  be 
entirely  in  accord  with  the  structure  of  the  labial  region. 
The  oesophagus  maintains  the  same  diameter  until  after  it 
passes  through  the  nerve-ring;  it  then  expands  rather  rap- 
idly so  as  to  form  the  pyriform  cardiac  bulb  nearly  two-thirds 
as  wide  as  the  base  of  the  neck.  There  is  a  flattish-conoid 
cardia,  one-third  as  wide  as  the  base  of  the  neck.  The  front 
end  of  the  intestine  is  pressed  to  one  side  by  the  strongly 
developed  renette  cell,  but  behind  this  cell  it  becomes  about 
two-thirds  to  three-fourths  as  wide  as  the  body;  its  cross- 
section  probably  is  composed  of  six  or  more  cells.  These 
cells  contain  scattered  yellowish  to  brownish  granules  of  small  but  variable  size. 
The  anus  is  rather  inconspicuous.  The  rectum  is  about  as  long  as  the  anal  body 
diameter.  The  tail  is  at  first  conoid,  so  that  at  a  distance  from  the  anus  equal 
to  five  times  the  anal  body  diameter,  its  diameter  is  not  over  one-sixth  as  great 
as  at  the  base.  The  remainder  of  the  tail,  probably  a  short  part  only,  is  missing. 
Caudal  glands  probably  located  in  the  base  of  the  tail.  The  renette  cell,  half 
as  wide  as  the  body  and  about  twice  as  long  as  it  is  wide,  is  located  behind  the 
base  of  the  neck  a  distance  equal  to  two  body  diameters.  From  the  slightly 
elevated  vulva  the  rather  massive  vagina  leads  inward  fully  half  way  across  the 
body.  About  eight  ova  are  arranged  single  file  in  each  ovary.  The  eggs  are 
two  to  three  times  as  long  as  the  body  is  wide,  and  a  little  less  than  one-third  as 
wide  as  long.  The  spermatozoa  seen  in  the  uterus  are  about  one-sixth  as  wide 
as  the  body,  and  are  finely  granular  and  have  their  chromatin  in  an  ellipsoidal 
form  surrounded  by  a  clear  area. 

Habitat:  Punta  Arenas,  Pacific  Coast  of  Costa  Rica.  The  following  are  the 
actual  measurements  in  microns:  n  ?s._  m.  '"-4ior"'  658  Fig.  53o. 

«./  •*^::'».-  ;•«.'".'  M'*900-  ..... 

b.  Pseudolella  granulifera  n.  sp.  Type  species.  Cuticle  as  in  P.  cephalata, 
but  without  wings.  Neck  convex-conoid  anteriorly  ;  especially  at  the  head,  which 
is  somewhat  bluntly  pointed.  Cephalic  setae  four,  arcuate,  spreading,  and  one- 
third  as  long  as  the  corresponding  diameter  of  the  head,  arranged  about  one- 
fourth  of  the  distance  back  to  the  beginning  of  the  tubular  portion  of  the  pharynx. 
Lips  confluent,  obscure,  probably  three  in  number.  No  labial  papillae  seen. 
Amphids  long,  slender;  beginning  some  distance  behind  the  pharynx  and  extend- 
ing forward  in  the  form  of  a  band  or  groove  about  half  as  wide  as  the  pharynx, 
and  having  refractive  cutinized  edges.  This  band  extends  to  very  near  the  lips, 
then  suddenly  narrows  and  turns  back  on  itself  and  ends  indefinitely  in  front  of 


PSEUDOLELLA 


269 


the  middle  of  the  pharynx.  At  its  widest,  i.e.,  toward  the  front,  the  amphid  is 
a  little  narrower  than  the  pharynx.  Lips  relatively  thick,  closing  to  form  an 
exceedingly  narrow,  cutinized  vestibule.  Pharynx  and  all  parts  of  the  alimentary 
canal  like  those  of  P.  cephalata.  Pharynx  sub-uniform,  about  one-sixth  as  wide 
as  the  base  of  the  head.  A  little  behind  the  lips  the  lining  of  the  pharynx  is 
discontinuous  and  the  cavity  bends  slightly  toward  the  ventral  side,  and  there 
appears  to  be  a  pair  of  very  small,  ventrally  submedian  onchia  of  equilateral 
profile.  It  is  difficult  to  make  out  the  details  sufficiently  well  to  state  positively 
that  these  refractive,  cutinous  elements  are  homologous  with  ordinary  onchia. 
Opposite  the  onchia  on  the  dorsal  side  the  cutinized,  pharyngeal  elements  are 
discontinuous,  two  or  three  in  number,  but  not  very  variable  in  character.  The 
onchia  and  the  elements  opposite  them  and  in  front 'of  them  are  fully  as  robust 
as  the  walls  of  the  pharynx,  of  which  the  ventral  side  supporting  the  "onchia" 
is  considerably  thicker  than  the  dorsal.  The  cross-section  of  the  intestine 
appears  to  be  made  up  of  few  cells,  perhaps  only  two  or  three.  The  granules  in 
the  intestinal  cells,  the  largest  of  which  are  half  as  wide  as  the  nucleus  of  the 
renette  cell,  are  a  very  conspicuous  feature  and  give  rise  to  a  very  indistinct 
tessellated  effect.  In  its  anterior  half  the  tail  is  conoid  from  the  anus,  and  at  the 
middle  is  one-fifth  as  wide  as  at  the  base.  Thence  onward,  it  tapers  but  little 
and  ends  in  a  somewhat  rounded,  unarmed  spinneret.  There  are  no  caudal  setae. 
Caudal  glands  occur  in  the  anterior  part  of  the  tail.  Lateral  fields  indistinct, 
apparently  one-third  as  wide"  as  the  body.  Both  before  and  behind  the  renette 
cell  there  are  bodies  of  unknown  significance  that  stain  with  carmine.  Nucleus 
of  the  renette  cell  distinct,  slung  in  a  conspicuous  protoplasmic  network.  Behind 
the  renette  cell  is  a  spindle-shaped,  distinctly  nucleated  cell  fully  one-third  as 
wide  as  the  body  and  about  twice  as  long  as  wide.  Still  further  back,  after  a 


.HI  .' 


4.1        7-          12.7  4M-°        86. 

2y?'   "%  *  *ij"  "  "    3.8 '^N- 2.9 

considerable  interval,  there  is 
another  similar  cell  of  larger 
size;  these  two  latter  cells  seem 
connected  by  a  narrow  process, 
and  the  anterior  smaller  cell 
presents  a  narrow  process 
extending  forward.  Spicula  uni- 
form, arcuate,  one  and  one-half 


s~---  ' 

times  as  long  as  the  anal  body 
diameter;  their  proximal  ends  rather  prominently  and  obliquely  cephalated  by 
expansion.  Proximal  ends  a  little  dorsad  from  the  body-axis.  The  spicula 
taper  to  a  fairly  acute  point  in  the  distal  fourths  and  their  cutinized  framework 
is  duplex;  at  their  widest  part,  the  middle  part,  the  spicula  are  about  one-sixth 
as  wide  as  the  corresponding  portion  of  the  body.  Two  accessory  pieces  adjoin- 
ing the  distal  fourths  of  the  spicula;  extending  backward  at  right  angles  to  the 
spicula  are  the  blunt  apophyses  three-fifths  as  long  as  the  anal  body  diameter. 
The  number  and  the  structure  of  the  testes  is  uncertain,  but  apparently  there 
are  two,  of  which  the  anterior  is  reflexed  and  the  posterior  outstretched.  The 
sexual  cells  are  of  unusually  large  size  and  their  walls  appear  to  divide  up  the 
testes  in  an  irregular  geometric  fashion. 
Habitat:  Marine  mud  and  sand,  Noumea,  New  Caledonia.  Fig  536. 


270 


ORDER   POLYLAIMIA 


V.  Order  Polylaimia 

This  order  cannot  at  present  be  so  satisfactorily  defined  as  most  of  the  others 
herein  represented.  There  probably  can  be  removed  from  it  sooner  or  later  a 
number  of  groups  of  ordinal  rank,  but  the  time  seems  hardly  yet  ripe  for  such 
a  removal.  For  the  present,  therefore,  the  genera  and  families  ranged  under 
this  name  are  of  a  more  heterogeneous  character  than  under  most  of  the  other 
twelve  orders  here  presented.  Some  slight  effort  has  been  made,  here  as  else- 
where, to  place  these  new  genera  in  the  order  of  their  family  relationships.  In 
general,  the  genera  that  are  first  mentioned  in  an  ordinal  group,  and  the  genera 
placed  at  the  end  of  the  group,  as  here  presented,  exhibit  more  or  less  manifest 
relationships  to  genera  included  in  other  orders.  (See  p.  217.) 

54.  Cephalobium  microbivorum  n.  sp.  The  wing  begins  near 
the  head  and  ends  near  the  terminus.  Its  optical  expression  is 
either  a  pair  of  lines,  or  a  single  line,  in  the  middle  of  a  field  one- 
twelfth  as  wide  as  the  body.  The  contour  of  the  body  may 
become  crenate  in  the  anal  region.  There  are  about  thirteen 
lateral  organs  in  each  lateral  field  connected  with  pores  in 
cuticle  (see  org.  lat.,  Fig.  54).  Base  of  the  pharynx  containing 
a  large,  complicated  and  peculiar  dorsal  glottoid  organ.  No 
amphids.  The  rather  thin-walled  intestine  is  set  off  by  a  collum 
one-eighth  as  wide  as  the  neck,  and  has  a  rather  distinct  lumen. 
It  becomes  at  once  five-sixths  as  wide  as  the  body,  and  in  cross- 
section  presents  two  to  four  cells.  From  the  somewhat  depressed 
anus,  the  narrow,  cutinized  rectum  extends  inward  a  distance 
one  and  one-fourth  tunes  as  great  as  the  anal  body  diameter. 
Scattered  yellowish  granules  of  variable  size  occur  in  the  cells 
of  the  intestine,  the  largest  being  one-twenty-fifth  as  wide  as 
the  body.  In  addition,  there  are  numerous  very  small  granules. 
;  The  subarcuate,  conoid  tail  tapers  from  in  front  of  the  anus  to 
the  acute  fine  terminus.  There  is  no  spinneret.  From  the  ele- 
vated vulva,  the  rather  small,  somewhat  weak  vagina  extends 
inward  one-fourth  the  way  across  the  body.  Along  the  middle 
half  of  the  body  the  two  equal  uteri  contain  ellipsoidal  eggs 
two-thirds  as  long  as  the  body  is  wide,  which  are  deposited  after 
segmentation  begins.  No  embryos  were  seen  in  these  eggs, — 
only  blastulas.  For  the  most  part  the  ova  are  arranged  irregu- 
larly in  the  somewhat  tapering  ovaries.  The  rather  strong, 
slender,  tapering,  subacute  spicula,  when  seen  in  profile,  have 
their  proximal  ends  nearly  opposite  the  body-axis.  Toward 
_J-.___l(l!i3-=i?-'§___'l'«>_'l-__8*-_-  their  distal  ends  four  slender 

stiffening  pieces  are  apparent. 

i.z    w.  _!?.       74-*       *>.  There  is  a  strong,   and  rather 

i3T«Vf  "  solidj  straight  accessory  piece, 
bending  back  from  the  spicula  at  an  angle  of  about  90  degrees,  so  that  its  proxi- 
mal end  lies  opposite  the  body-axis.  Near  the  beginning  of  the  second  quarter 
of  the  tail  there  is  a  pair  of  lateral  pores  (?)  similar  to  those  on  the  female. 
On  the  female  these  pores  have  been  shown  by  intra  vitam  staining  to  be  homol- 
ogous with  those  mentioned  above,  and  shown  in  the  illustration  at  por  lat. 
Pairs  of  papillae  on  the  tail  of  the  male  flattish-conoid,  plainly  innervated,  rather 


ayJai 


CEPHALOBIUM,  BLATTOPHILA,  CATANEMA 


271 


inconspicuous,  occupying  the  anterior  two-thirds  of  the  tail,  thus:  1()1;  111;  1. 
The  members  of  the  posterior  four  pairs  are  not  located  exactly  opposite  each 
other,  the  right  hand  member 
each  pair  being  slightly  behind  the 
left  hand  member.  Spicula  con- 
spicuous, rather  close  together;  at 
the  widest  part  about  one-eighth 
wide  as  the  corresponding  portion 
of  the  body,  ending  in  minute  "bi 
tons."  The  lateral  pores  on  the 


tail  are  the  final  members  of  the 


•xayg/at,    alfit  taoe   segmmr. 


series  of  lateral  organs. 
Habitat:  Intestine  of  field  cricket,  Gryllus  neglectus  Scudd. 


Fig.  54a  and  b. 

77. 


55.  Blattophila    sphaerolaima    n.    sp. 


Cuticle 


marked  with  plain  transverse  striae,  3  microns  apart  on  the  head  and  24  microns 
apart  on  the  body,  where  they  are  much  less  plainly  to  be  seen,  though  they  cause 
a  slight  crenation  of  contour.  No  amphids  or  setae  of  any  sort.  The  head  is 
somewhat  hemispherical,  bearing  very  small  lips  almost  in  the  form  of  an  annular 
elevation  about  the  mouth.  The  pharynx  and  its  apophyses  are  contained  in  a 
small  spherical  pharyngeal  bulb, — hence  the  specific  name.  When  closed,  the 
pharynx  is  a  prismoid  cavity  one-fourth  as  deep  as  the  head  is  wide  and  about 
half  as  wide  as  deep,  and  backward  from  its  base  spring  apophyses,  a  dorsal  one 
dominating.  The  mouth  can  probably  be  turned  partially  inside  out.  The  ante- 
rior three-fourths  of  the  oesophagus  is  clavate,  averaging  one-third  as  wide  as 
the  corresponding  part  of  the  neck;  this  anterior  part  is  connected  by  a  narrow 
and  very  short  tube  with  an  oblate  cardiac  bulb  one-half  as  wide  as  the  base  of 
the  neck.  The  intestine,  which  appears  to  be  only  one-third  as  wide  as  the  body, 
is  set  off  by  a  broad  and  very  deep  constriction.  The  rectum  is  one  and  one-half 
times  as  long  as  the  anal  body-diameter.  The  renette  plexus  is  quadruple. 
The  nerve-ring  encircles  the  oesophagus  obliquely.  The  acute,  conoid  tail  tapers 
rapidly  near  the  anus,  where  there  is  a  somewhat  indistinct  constriction.  The 
anterior  lip  of  the  anus  projects.  The  vulva  is  not  very  prominent.  The  num- 
erous elongated  ellipsoidal  eggs  measure  40-48  X  88-104  microns,  and  may  seg- 
ment before  deposition. 

.4         7.7        15-  «K  82. 

i._      3.       4.5  /      5.4      ^3.1  Of  the  papillae  on  the  male  two  are  pre-anal, 

being  large  submedian  ones  adjoining  the  anus  and  having  a  truncate-conoid 
form  with  a  mucro;  there  are  also  two  post-anal  papillae  similar  to  the  foregoing 
but  smaller,  and  removed  from  the  anus  a  distance  equal  to  one-third  of  the  body 
diameter.  The  spicula  appear  to  be  represented  by  a  mere  rudimentary  point, 
—no  longer  than  the  larger  papillae,— conical  in  form  and  projecting  with  the 
anus  when  the  nema  is  killed  with  osmic  acid.  The  single  testis  is  reflexed  at  a 
point  somewhat  farther  behind  the  cardia  than  the  latter  is  behind  the  head. 

Habitat:  Intestine  of  Panesthia  brevicollis  Sauss.,  the  common  spiny-legged 
wild  cockroach ;  Moss  Vale,  New  South  Wales,  Australia.    1889.    Osmic  to  water  ? 


56.  Catanema  exile  n.  sp.  '-       L       —         1-  ~~Nr1-?  The  mouth  opening  is 

closed  by  three  or  six  very  minute,  slightly  refractive  structures.  About  oppo- 
site the  bases  of  the  cephalic  setae  there  are  exceedingly  minute  onchia  (?), 
possibly  six,— difficult  to  see  in  profile;  impossible  to  count  because  of  their 


272 


ORDER    POLYLAIMIA 


small  size  and  their  overlapping.  Amphids  forward-pointing,  minute,  difficult 
to  see.  The  oesophagus  becomes  slightly  narrower  where  it  passes  through  the 
nerve-ring;  posterior  bulb  napiform,  three-fourths  as  wide  as  the  base  of  the 
neck.  There  is  no  distinct  cardia.  The  thick-walled  intestine  becomes  at  once 
about  two-thirds  as  wide  as  the  body,  and  its  cross-section  is  made  up  of  about 


Wj? 


four  cells,  which  are 
packed  with  granules 
of  uniform  size.  The 
lateral  fields  are  about 
one-third  as  wide  as  the 
body,  and  contain  a 
series  of  cells  of  large 
size.  The  nerve-ring 
surrounds  the  oesoph- 
agus  obliquely.  There 
is  a  single,  small,  elon- 
spn  gated,  very  inconspic- 
uous ventral  supple- 
mentary  organ  of  the 
ordinary  kind  opposite 
the  posterior  part  of 
the  spicula,  and  in 
;  front  of  it  a  number  of 
minute  ventral  setae. 
Seven  pairs  of  sub- 
ventral  tubular  sup- 
y  7cft  plements  occur  on  the 
tail.  The  ejaculatory 
duct  is  about  two-fifths  as  wide  as  the  body.  The  caudal  glands  are  evidently 
located  in  front  of  the  tail,  but  their  exact  position  has  not  been  made  out. 

Habitat:  Marine  sand  about  the  bases  of  algae,  in  surf,  Island  off  Port  Royal, 
Jamaica.  This  genus  resembles  Laxonema  in  many  respects,  and  also  resembles 
Laxus  but  differs  in  the  form  of  the  lateral  organs  and  in  other  ways.  Sublimate 
to  balsam.  Fig.  56. 

57.  Zalonema  nudum  n.  sp.  Cuticle  naked.  The  face  view  of  the  striae  gives 
the  impression  of  a  series  of  narrow,  contiguous  hoops.  The  cuticle  becomes 
thicker  on  the  neck,  and  much  thicker  on  the  head.  Lips,  thick,  small,  plain. 
On  the  male  there  are  very  distinct  and  prominent  wings,  beginning  about  three 
times  as  far  in  front  of  the  anus  as  the  terminus  is  behind  it.  Each  wing  extends 
backward  and  ends  opposite  the  proximal  ends  of  the  spicula.  The  width  of 
this  wing  is  about  equal  to  the  corresponding  thickness  of  the  dorsal  or  ventral 
cuticle  as  seen  in  optical  section.  None  of  the  irregularities  in  the  wall  of  the 
pharynx  are  suggestive  of  the  ordinary  pharyngeal  organs,  and  yet  they  are  very 
distinct  features.  Two  of  them  are  rather  prominent,  one  on  the  dorsal  side, 
opposite  the  anterior  portion  of  the  cephalic  thickening,  and  the  other  on  the 
ventral  side  opposite  the  middle  or  posterior  portion  of  the  cephalic  thickening. 
The  oesophagus  continues  with  the  same  diameter  until  it  expands  to  form  the 
very  broadly  pyriform  or  napiform  cardiac  bulb,  which  is  three-fourths  as  wide 
as  the  base  of  the  neck.  The  lining  of  the  oesophagus  occupies  nearly  one-third 
of  the  optical  section.  The  oesophageal  lumen  continues  through  the  bulb. 


ZALONEMA,    PSEUDONCHUS 


273 


The  intestine  joins  the  middle  of  the  posterior  surface  of  the  cardiac  bulb,  and 
at  this  point  the  collum  is  nearly  one-third  as  wide  as  the  base  of  the  neck.     The 
rather  thin-walled  intestine  becomes  at  once  about  two-thirds  as  wide  as  the 
body.     From  the  nearly  continuous  anus,  the  tail  is  arcuate  and  conoid.     There 
are  no  supple-          fi 
mentary    or-  j^'  •  '^  •  •  •••  • 

gans.     The 
moderately  V?. .  ,5.^  . .  ?-.7. . 
stout  spicula  1- 

taper  to  a  blunt  point  in  their  distal  halves. 
At  their  widest  part  they  are  about  one-fifth 
to  one-sixth  as  wide  as  the  corresponding 
part  of  the  body;  they  are  accompanied  by  X750 
accessory  pieces  half  as  long.     The  distal  ends  of  the  accessory  pieces  are  applied 
closely  to  the  spicula,  but  the  proximal  ends  curve  away  slightly  and  then  recurve. 
The  ejaculatory  duct  is  about  one-third  as  wide  as  the  body.     Apparently  there 
is  but  a  single  testis. 
Habitat.  Marine  mud  and  sand,  Noumea,  New  Caledonia.     Sublimate  to  bal- 


58.  Psendcmc/ms  rotundicephalus  n.  sp.   i^     i-5      i_J>          '-8  In  most 

portions  of  the  body  longitudinal  striations  have  been  observed,  apparently 
connected  with  the  cuticle  rather  than  with  the  musculature.  Neck  cylindroid. 
Lips  two,  each  lateral.  See  Fig.  58.  The  mouth  is  very  difficult  to  see  in  the 
lateral  view.  In  the  dorso-ventral  view  it  is  easily  seen,  and  is  found  to  be  a 
dorso-ventral  opening  running  across  the  head.  Each  lip  has  about  six  very 
minute,  refractive,  double,  cutinous  markings,  each  presenting  two  blunt-edged 
"teeth"  directed  toward  the  base  of  the  pharynx.  It  appears  that  these  repre- 
sent foldings  in  the  closed  lips.  In  any  case  they  represent,  when  viewed  later- 
ally, the  roof  of  the  pharynx,  located  opposite  the  bases  of  the  anterior  cephalic 
setae.  The  elements  in  the  pharynx  opposite  the  anterior  borders  of  the  amphids, 
which,  at  first  sight,  appear  to  be  onchia,  prove  on  careful  examination  to  be 
ridges,  (see  pseudon,  in  the  illustrations).  The  pharynx  is  unusual  in  structure 
and  rather  difficult  to  understand.  The  amphids  of  the  female  occur  in  about 
the  same  position  as  those  of  the  male,  but  instead  of  appearing  spiral  appear 


wind.  The  narrow  oesoph- 
agus has  the  same  diameter 
until  it  expands  to  form  the 
somewhat  obscurely  pyri- 
form  bulb,  which  is  three- 
fourths  as  wide  as  the  base 

x750  mm  W  yn  of  the  neck.    There  is  a 

flattish  cardia,  about  one-third  as  wide  as  the  base  of  the  neck.  The  intestine  is 
set  off  by  a  constriction  about  one-half  as  wide  as  the  body,  and  in  cross-section 
presents  about  half  a  dozen  cells.  There  appear  to  be  faint  indications  of  the 
presence  of  wings.  Renette  unknown.  Lateral  fields  are  about  one-fourth  as 
wide  as  the  body.  Nerve-ring  oblique.  The  tail  is  convex-conoid  to  the  termi- 


274  ORDER   POLYLAIMIA 

nus,  where  the  conoid  spinneret  has  a  diameter  about  one-fifth  as  great  as  that 
of  the  base  of  the  tail.  From  the  slightly  elevated  vulva  the  vagina  leads  inward 
half  way  across  the  body,  where  it  joins  the  two,  symmetrically  placed  uteri. 
The  ovaries  reach  about  half  way  back  to  the  vulva,  at  least  in  specimens  in 
which  the  uteri  are  empty.  There  are  eight  to  ten  ova  in  each  ovary,  arranged 
single  file. 

1.1       3-3       5-8        "-K          95-9  >,  6 

tj      1.3      M         1.4^1.4  The  spinneret  of  the  male  is  about  one-third  as 

wide  as  the  base  of  the  tail.  No  supplements  or  special  setae  or  papillae  have 
been  observed  either  in  front  of  the  anus  or  behind  it.  The  spicula  are  rather 
uniform  and  taper  to  an  acute  point  in  their  distal  thirds;  in  profile  their  proxi- 
mal ends  are  seen  to  lie  near  the  ventral  surface  of  the  body.  The  ejaculatory 
duct  is  about  half  as  wide  as  the  body. 

Habitat:  Mud,  tide  pool,  Portsmouth,  N.  H.,  U.  S.  A.  Sublimate  to  balsam. 
Fig.  58,  p.  273. 

1.5       6.3  .    10.       "*41»"       85. 

59.  Polylaimium  exile  n.  sp.    ••>      L    '    1,2        1.2        i.  >lb"  Striae  of  the  thin 
cuticle  minute.     It  seems  very  likely  that  four  cephalic  setae  have  been  lost 
from  the  specimen  from  which  the  description  and  illustration  are  drawn.     Lips 
three,  and  double,  (or  possibly  six),  with  six  minute  labial  papillae.     Cuticle 
naked.    Neck  convex-conoid,  especially  toward  the  head.     The  oesophagus  at 
the  nerve-ring  is  one-half,  just  in  front  of  the  cardiac  swelling  one-half,  and 
finally  two-thirds,  as  wide  as  the  corresponding  portion  of  the  neck.     The  elon- 
Ib(6)          aJ  (6)  gate(*  to  Pyrifp™1  cardiac  bulb  is  very  small.     The  lining  of  the 

""/56k  oesophagus  is  quite  distinct  and  at  first  is  indicated  by  two  refrac- 

ph      ml     . /^  tive  lines,  occupying  a  space  one-sixth  as  wide  as  that  of  the 

,  1 1    k         oesophagus.    There  appear  to  be  no  glands  in  its  fine  colorless 

ifr l          musculature.     There  is  an  indistinct  cardia.     The  thick-walled 

ejf  |n  ..  fjj  intestine  is  set  off  by  a  collum  one-third  as  wide  as  the  base  of  the 
I  I  ]  I  Yf  neck;  it  has  a  faint  lumen  and  becomes  at  once  two-thirds  as 
.  50  .M  1  w  wide  as  the  body.  In  cross-section  it  is  made  up  of  two  to  three 
cells.  Anus  more  or  less  continuous;  rectum  somewhat  cutinized,  equal  in 
length  to  the  anal  body-diameter.  The  granules  contained  in  the  intestinal 
cells  are  numerous,  uniform  and  colorless.  The  tail  is  conoid  from  the  anus, 
and  then  cylindroid  in  the  posterior  half,  where  it  is  two-thirds  as  wide  as  at  the 
base.  It  is  probable  that  the  caudal  glands  are  small  and  located  near  the  anus. 
There  are  no  caudal  setae.  Renette  present;  excretory  pore  probably  located 
near  the  nerve-ring.  Full-grown  ova  are  twice  as  long  as  the  body  is  wide, 
and  nearly  one-half  as  wide  as  long.  The  reflexed  parts  of  the  ovaries  reach 
about  three  to  four  body-widths  back  toward  the  vulva. 

Habitat:  Sand  below  low-tide  mark,  Belmar,  New  Jersey,  U.  S.  A.  Sublimate 
to  balsam.  Apparently  the  species  is  syngonic.  Up  to  the  present  time 
extremely  few  free-living  marine  nemas  have  been  observed  to  be  syngonic. 
A  similar  species  with  four  setae  occurs  at  Woods  Hole,  Mass,  U.  S.  A.  Fig.  59. 

60.  Myolaimus  heterurus  n.  sp.     Cuticle  thin,  naked;  striae  fine.     Lips  thin, 
low,  flat,  confluent;  six,  or  three  and  two-parted.     Amphids  faint,  in  the  form 
of  transverse  slits.     That  portion  of  the  pharynx  in  front  of  the  amphids  is 
about  half  as  wide  as  the  lip  region;  this  chamber  is  continued  by  a  narrower 
tubular  portion,  nearly  one-third  as  long  as  the  neck  and  surrounded  by  a  pecul- 
iar radial  musculature,  differing  from  that  of  the  oesophagus  proper.     Nearly  as 
far  behind  the  amphids  as  these  latter  are  behind  the  anterior  extremity,  there 
is  a  prominent  infolding  in  the  wall  of  the  pharynx.     The  amphids  are  difficult 


MYOLAIMUS 


275 


to  detect  with  the  nema  in  profile,—  more  easily  when  viewed  dorso-ventrally. 
Behind  the  anterior  chamber  of  the  pharynx,  which  in  many  respects  resembles 
that  of  Diplogaster,  there  is  a  muscular  portion  closely  resembling  the  oesophagus 
in  size  and  structure,  but  which  seems  undoubtedly  pharyngeal.  This  is  indi- 
cated in  two  ways;  first,  the  lining  is  different  from  that  of  the  portion  of  the 
oesophagus  immediately  following  it,  and  second,  it  behaves  differently  with 
staining  material,  indicating  that  its  muscular  wall  also  is  considerably  different 
in  nature  from  that  of  the  oesophagus.  The  dimensions  given  in  the  formulae 
relate  to  the  anterior  or  labial  chamber.  At  the  base  of  the  anterior  pharyngeal 
chamber  there  appear  to 


13.7     25.2 


A        3.9 


(Sflpft/m 


be  minute  cutinous  pro- 
cesses  which  perhaps  may 
function  as  onchia.  It 
would  appear  possible 

that  all  that  portion  of  the  pharynx  in  front  of  the  folds  ' 
in  its  lining  are  capable  of  being  opened  out  or  everted. 
From  the  pharynx  the  oesophagus  is  cylindrical  to  near' 
the  nerve-ring,  where  it  diminishes  rather  suddenly  in 
diameter  near  the  very  faint  vestiges  (?)  of  a  median 
structure.  The  vestiges  consist  in  internal  modifications 
of  the  oesophagus  only.  From  the  nerve-ring  onward  the 
oesophageal  tube  is  about  two-fifths  as  wide  as  the  corre- 
sponding portion  of  the  neck.  It  finally  expands  to  form  the  elongated-ellip- 
soidal cardiac  bulb,  which  bears  a  more  or  less  distinct  cardia,  and  is  separated 
from  the  intestine  by  a  shallow  constriction.  The  cardiac  valvular  apparatus 
appears  to  be  comparatively  simple.  The  intestine  becomes  at  once  four-fifths 
as  wide  as  the  body.  The  intestinal  walls  are  rather  thick,  and  the  cells  are 
packed  with  minute  granules.  The  rectum  is  about  twice  as  long  as  the  anal 
body  diameter.  The  lateral  fields  appear  to  be  half  as  wide  as  the  body. 
The  tail  of  the  female  is  conical  to  the  acute  terminus  and  presents  the  peculiarity 
of  diminishing  in  diameter  very  suddenly  immediately  behind  the  anus,  the  dimi- 
nution taking  place  on  the  ventral  side.  The  anal  region  is,  therefore,  conspic- 
uous on  this  account,  as  well  as  on  account  of  the  fact  that  it  is  slightly  depressed, 
and  again  on  account  of  the  refractive  nature  of  the  lining  of  the  comparatively 
long  and  large  rectum.  The  salient  lips  of  the  vulva  are  conspicuous,  a  property 
that  is  increased  by  the  refractive  nature  of  the  lining  of  the  vagina,  which  extends 
inward  two-fifths  the  distance  across  the  body.  Tail  of  the  male  very  different 
from  that  of  the  female.  There  is  a  bursal  membrane  connected  with  the  digi- 
tate organs  shown  in  Fig.  60.  The  specimens  seen  were  molting,  so  that  the  exact 
nature  of  the  membrane,  which  is  believed  to  connect  these  organs  one  with 
another,  has  not  been  deciphered.  It  seems  also  certain,  however,  that  the  ante- 
rior four  are  joined  together  by  means  of  a  ventrally  submedian  membrane 
somewhat  as  in  the  case  of  the  bursa  in  Rhabditis.  The  spicula  are  very  weak 
and  poorly  developed  in  the  specimens  thus  far  seen.  They  appear  to  be  as 
long  as  the  tail,  and  are  probably  cephalated  at  their  proximal  ends  by  constric- 
tion; but  they  are  very  difficult  to  discern,  and  it  is  possible  that  the  appearances 
are  deceptive  and  that  they  are  altogether  absent.  The  testis  extends  forward 
to  near  the  posterior  end  of  the  neck  and  appears  to  be  reflexed  for  a  short  dis- 
tance, but  this  is  somewhat  uncertain. 

Habitat:  Loamy  soil,  El  Paso,  Texas,  U.  S.  A.     Flemming  to  glycerine  jelly. 
Fig.  60. 


276  ORDER   POLYLAIMIA 

9-5       13.        16-6          <45;          83. 

61.  Myctolaimus  pellucidus  n.  sp. 
traces  of  a  very  fine  transverse  striation.  No  amphids  or  setae  of  any  sort  to 
be  seen.  Head  continuous.  Six  relatively  large,  obtusely  conical  lips,  each 
supplied  with  an  obscure  papilla,  surround  the  mouth.  The  cuticle  at  the  base 
of  the  lips,  and  at  the  beginning  of  the  pharyngeal  tube,  is  somewhat  thickened, 
and  this  gives  rise  to  obscure  rings  at  the  base  of  the  lip-region.  The  unusually 
long  pharynx  is  divided  into  two  very  distinct  parts  of  about  equal  length, 
together  occupying  nearly  two-thirds  the  length  of  the  neck.  The  anterior  part 
is  a  simple,  narrow,  straight  strongly  cutinized  tube,  having  a  lumen  one-third  as 
wide  as  the  lip-region.  The  succeeding  second  part  of  the  pharynx  is  a  cylindroid 
bulb,  rounded  at  both  ends,  and  two-thirds  as  wide  as  the  corresponding  part  of 
the  neck.  Its  lumen  is  triangular  and  of  about  the  same  width  as  that  of  the 
anterior  part  of  the  pharynx,  from  which  it  is  separated  by  a  distinct  break  in 
the  continuity  of  the  cutinous  lining.  From  this  elongated  bulb  a  tube  one-sixth 
as  wide  as  the  corresponding  part  of  the  neck  passes  backward  and  gradually 
expands  into  a  valveless  bulb  half  as  wide  as  the  base  of  the  neck,  thus  complet- 
ing the  oesophagus.  The  intestine,  which  at  first  is  colorless  and  transparent  and 
only  one-fourth  as  wide  as  the  body,  gradually  expands  and  becomes  half  as  wide 
as  the  body  and  distinctly  granular.  The  refractive  lining  of  the  intestine  is  a 
prominent  feature.  The  cardia  is  unusually  long  and  narrow,  and  opens  into  a 
small  cardiac  cavity.  The  cells  composing  the  intestine  are  relatively  large. 
The  length  of  the  well-cutinized  rectum  is  about  one  and  one-half  times  that  of 
the  anal  body  diameter.  Renettte  unknown.  The  width  of  the  lateral  fields  is 
one-third  that  of  the  body.  The  nerve-ring  is  small  and  narrow.  The  acute 
tail  is  almost  exactly  conical.  The  vulva  is  very  slightly  elevated.  The  ovaries 
extend  back  as  far  as  the  vulva,  and  are  often  there  again  reflexed.  Each  uterus 
contains  one  to  two  eggs,  measuring  32  X  56  microns.  Segmentation  takes  place 
in  the  uterus,  and  proceeds  to  at  least  the  gastrula  stage,  probably  beyond  it. 


4.9  3j  3-2  5.7  "">•-  2.5 1  The  tail  of  the  male  instead  of  being  conical  is 
convex-conoid  in  the  anterior  half,  tapering  in  this  part  in  such  a  fashion  that 
the  middle  of  the  tail  is  one-fourth  as  wide  as  the  base;  thence  onward  the  tail  is 
cylindroid  to  the  acute  terminus.  While  the  anterior  part  of  the  tail  is  ventrally 
arcuate,  the  remainder  is  dorsally  arcuate.  No  ventral  supplements  or  bursa. 
Nine  pairs  of  papillae,  mostly  finger-shaped,  are  arranged  as  follows:  1;  1(1)1,  1; 
1,  3.  The  linear,  tapering,  rather  blunt  spicula  somewhat  exceed  the  anal  body 
diameter  in  length.  The  spicula  are  supported  by  sigmoid  accessory  pieces  half 
as  long  as  they  themselves.  The  reflexed  part  of  the  testis  is  nearly  equal  to  the 
neck  in  length;  it  can  be  seen  to  contain  small  glassy,  globular  spermatocytes, 
which  reach  their  full  growth  near  the  middle  of  the  body,  becoming  as  long  as 
the  body  is  wide  and  two-thirds  as  wide  as  long.  At  this  stage  they  are  granular, 
with  a  large  central  nucleus  containing  a  prominent  nucleolus.  By  division  these 
large  cells  give  rise  to  the  granular  spermatozoa,  an  elongated  parcel  of  a  dozen 
or  more  of  which  is  usually  to  be  seen  in  each  uterus  of  the  female. 

Habitat:  Sheep-dung,  Moss  Vale,  New  South  Wales,  September  2,  1894.  It 
will  be  seen  that  this  genus  is  similar  to  Cephalobus.  It  is  equally  clear  that  it 
is  generically  distinct.  It  is  unfortunate  that  no  specimens  of  this  species  were 
preserved,  and  hence  no  drawings  can  be  presented.  This  is  all  the  more  to  be 
regretted  because  the  genus  is  evidently  closely  related  not  only  to  Cephalobus 
but  to  one  or  two  others  of  similar  character. 


APODONTIUM,    IRONELLA 


277 


VI.  Order  Apodontia 


i.'5"\(i.*'*  2-3""  Striae  resolv- 


.7       5.          9.4 

62.  Apodontium  pacificum  n.  sp.  '.?"/"  Y.z""i.'3 

able  into  dot-like  elements.  Neck  cylindroid  posteriorly,  convex-conoid  ante- 
riorly. The  cylindroid  oesophagus  ends  in  an  inconspicuous,  flattish-conoid 
cardia  one-third  as  wide  as  the  base  of  the  neck.  The  thin-walled  intestine  is 
set  off  by  a  collum  two-thirds  as  wide  as  the  base  of  the  neck,  has  a  somewhat 
distinct  lumen,  becomes  at  once  two-thirds  as  wide  as  the  body,  and  in  cross- 
~^.mn(l(6l section  presents  three  to  four  cells  containing  granules  of 
,  uniform  size.  From  the  somewhat  elevated  anus  the  prom- 
"  inent  rectum  extends  inward  a  distance  equal  to  the  anal 
tsubcph  body  diameter.  Tail  conoid  from  the  anus.  The  conspicu- 
ous, more  or  less  elongated  caudal  glands  are  packed  in  a 
close  tandem  behind  the  anus  in  the  anterior  half  of  the 
•  Wt&il.  There  are  about  eight  ventrally  submedian  and  two 
•  dorsally  submedian  setae  on  each  side  of  the  tail.  These 
stoutish,  tapering  setae  are  about  one-fourth  as  long  as  the 
X750anal  body  diameter.  The  large  granular,  ellipsoidal  renette 
cell,  two-thirds  as  long  as  the  body  is  wide,  and  two-thirds  as  wide  as  long,  lies 
a  short  distance  behind  the  base  of  the  neck,  and  empties  through  an  ellipsoidal, 
thin-walled  ampulla.  The  nerve-ring  is  accompanied  by  obscure  nerve  cells. 
The  yellowish  spicula  are  slender  and  subacute.  Their  proximal  ends  appear 
to  lie  somewhat  dorsad  from  the  body-axis.  There  are  two  separate,  strong, 
rather  stout,  simple  accessory  pieces.  They  are  one-half  to  two-thirds  as  long 
as  the  anal  body  diameter,  and  their  proximal  ends  lie  near  the  dorsal  body 
wall.  There  are  no  supplementary  organs,  special  setae,  or  papillae  on  the  tail 
of  the  male.  The  ejaculatory  duct  is  one-third,  the  vas  deferens  one-third,  and 
the  testis  one-half,  as  wide  as  the  body.  The  testis  tapers  and  is  at  last  narrow. 
Habitat:  Marine;  Mollendo  and  Salaverry,  coast  of  Peru,  S.  A.  Sublimate  to 
balsam.  Fig.  62. 

8.7         1   20.  '=«  9*.    y .  ln 

63.  Ironella  prismatolaima  n.  sp.  /u*      i        i-9         2.  -T-*.  1.1     '       Lateral  wings 
very  faint.     Body  naked.     Lips  six,   very  tenuous,  revolute,  forming  a  short 
tube  one-fourth  as  wide  as  the  lip-region. 

There  are  six  obscure,  flat,  conical,  labial 
papillae,  not  shown  in  the  illustration. 
Labial  setae  minutely  "furcated"  at  the 
extremity.  Each  of  the  three  odontia  is 
duplex,  the  two  parts  of  the  submedian 
ones  being  of  unequal  size.  The  odontia 
are  contained  in  a  somewhat  napiform 
cavity.  Odontia  acute,  with  an  outward 
stroke;  when  at  rest  somewhat  outward- 
pointing,  and  blocking  the  entrance  to  the 
pharynx.  Posterior  part  of  the  napiform 
cavity  apparently  lined  with  exceedingly 
minute  denticles .  Neck  cylindroid. 
Amphids  faint,  apparently  consisting  of 
an  almost  imperceptible  transverse  groove  /  j 
partially  encircling  the  head.  The  cylin- 
droid oesophagus  is  at  the  nerve-ring  four-sevenths,  and  finally  three-fifths,  as  wide 
as  the  corresponding  portion  of  the  neck;  its  lining  is  prominent,  occupying  one- 
third  the  diameter  of  the  organ.  In  the  coarse,  colorless  musculature  there  are 


iP^O^i^r  In 
f  1  l|  I 


278 


ORDER  APODONTIA,  ORDER  SYNODOXTIA 


three  glands  which  empty  at  the  mouth.  There  is  a  cylindroid  cardia  two- 
sevenths  as  wide  as  the  base  of  the  neck.  The  thick-walled  intestine  is  set  off  by 
a  collum  one-third  as  wide  as  the  base  of  the  neck,  and  becomes  at  once  one-half 
to  three-fifths  as  wide  as  the  body.  Its  cross-section  is  composed  of  four  to  six 
cells.  It  has  a  faint  zig-zag  lumen.  Very  fine,  colorless,  more  or  less  polyhedral 
granules  of  variable  size  are  found  scattered  in  the  intestinal  cells.  The  largest 
of  these  are  one-twenty-fifth  as  wide  as  the  body.  They  give  rise  to  no  more 
than  a  faint  tessellation.  The  more  or  less  arcuate  tail  of  the  male  tapers  from 
in  front  of  the  anus,  and  is  first  conoid  then  cylindroid  and  two-fifths  as  wide  as 
at  the  anus.  The  caudal  glands  are  probably  preanal.  There  are  no  caudal 
setae.  The  lateral  fields  are  one-fourth  as  wide  as  the  body,  and  faintly  granular. 
The  very  frail,  straight,  slender,  subacute  spicula  become  arcuate  near  the  tips, 
and  are  faintly  cephalated  by  expansion.  Their  proximal  extremities  appear  to 
lie  dorsad  from  the  body-axis.  The  frail,  simple,  arcuate,  slender  accessory  piece 
lies  parallel  to,  and  is  two-fifths  as  long  as,  the  spicula.  There  is  a  single  supple- 
mentary organ  opposite  the  posterior  part  of  the  spicula.  The  internal  part  is 
refractive  and  more  or  less  irregularly  cylindrical,  and  bent  back  parallel  to  the 
ventral  surface.  It  is  one-half  as  long  as  the  body  is  wide,  and  one-fourth  to 
one-fifth  as  wide  as  long,  and  is  probably  protrusile  through  the  small,  short, 
cylindrical  element  at  the  ventral  surface,  where  there  is  also  a  single,  strongly 
curved  seta,  of  considerable  size.  The  ejaculatory  duct  is  one-third  as  wide  as 
the  body.  The  testes  are  characterized  by  the  presence  of  numerous,  elongated 
elements,  which  constitute  one  phase  in  the  development  of  the  sperm.  These 
elements  are  apparently  two-thirds  as  long  as  the  body  is  wide  and  one-fifth  to 
one-eighth  as  wide  as  long,  and  are  rounded  at  the  end.  From  the  living  nema. 
Habitat:  Sand,  Nobsca  Beach,  Woods  Hole,  below  low  tide.  Fig.  63. 

VH.  Order  Synodontia 

.8       12.7 20.2      "'58  93.6 

Chambersiellarodensn.sp.i-9      }./      3j         5.7        3.1 

radictr  Only  the  external  walls  of  the  six  odontia 
are  cutinized  and  this  portion,  but  not  the 
interior,  stains  very  strongly  in  acid-car- 
••••*  mine.  The  odontia  are  used  to  nibble  the 
mycelium  of  the  fungi  constituting  the  food. 
cut  The  cells  of  the  vas  deferens  are  packed  with 
transparent,  homogeneous,  ellipsoidal  gran- 
ules, whose  maximum  diameter  is  about  one- 
third  as  great  as  that  of  the  spermatozoa;  the 
cells  of  the  ejaculatory  duct  are  packed  with 
similar  granules  having  about  half  as  great  a 
diameter.  The  junction  of  the  ejaculatory 
duct  and  the  vas  deferens  is  distinctly  marked 
set  hi  by  the  change  in  the  size  of  the  granules  con- 
tained in  these  cells  composing  their  walls. 
The  lateral  pores  on  the  tail  of  Chambersiella 

\- w  rodens  connect  with  elongated,  clavate  cells 

\\  located  opposite  the  anus  in  a  lateral  position. 
\\  The  nuclei  of  these  cells  usually  lie  a  trifle 
X2000  behind  the  anal  region.  From  the  elevated 
KM-nore  and  conspicuous  vulva,  the  somewhat  cutin- 
cfearly  the  mandibles  and  the  setae.  ized  large  vagina  leads  inward  and  obliquely 

forward.     The  eggs  are  elongated,  apparently  more  or  less  long  and  slender. 
The  gently  tapering  ovary  contains  50-100  ova;  reflexed  to  near  anus. 


team 


cirtiM 


set  Ib 


CHAMBERSIELLA 


279 


.6         14.  20.8         5*OI  94.1 

1.7      1.7,     3^1         *.8-pi.5.  The  males  are  less  common  than 

Habitat:  Bark  of  a  great  variety  of  trees  set  cph  ht    set  cph  suta    ad 
in  many  parts  of  the  eastern  United  States; 
on  "Spanish  Moss,"  Miami,  Florida.    Flem-  .^  ^ 
ming's   solution   to   glycerine   jelly.     This 
genus  comprises  a  considerable  number  of  ^ 
species,  all  with  a  hooked  caudal  extremity. 
The  species  vary  considerably  in  the  labial       , 
accessories.     The  present  species  has  the    ^ 
strongest  mandibles  so  far  known  in  the 
genus.     These  nemas  are  highly  resistant  w 
to  drought  and  cold,  and  may  be  kept  on 
dried  bark  for  several  years  and  then  be  'm  ^ 
fully  revived  by  soaking  the  bark  in  water. 
They   may   be   repeatedly   frozen   in   and® 
thawed    out    without    injury.     Recently 
revived    specimens    are    mostly    immature  d  nm 
and  seem  to  present  an  empty  intestinal 
canal,  suggesting  that  on  the  approach  of  gj  an 
untoward   conditions,    they   evacuate    the 
canal.     Not  infrequently,  the  lip-region  of 
revived    specimens    appears    to    exhibit   a 
ndarlat .  .    ndmsc 


alhil 
6ppl 


VKtsecadS) 

spinet  seaid0 


tnatst  .--•••  'spaictprm  a/1 
pluglike  accession,  seen  also  in  the  mouth  opening  of  similarly  revived  Cepha- 
lobi.  The  opening  is  protected  during  "suspended  animation"  by  means  of  this 
dried-up  evacuation  from  the  oesophagus.  Fig.  64a,  p.  278;  Fig.  646. 

The  name  of  this  remarkable  genus,  the  abundant  species  of  which  are  widely 
distributed  on  trees,  commemorates  the  classic  work  in  this  field  of  Mr.  W.  E. 
Chambers,  through  whose  untimely  death  science  has  lost  one  of  its  greatest 
graphic  interpreters. 


280  ORDER    SYNODONTIA 

65.  Synodontium  fecundum  n.  sp.  About  forty  setae  occur  on  the  neck;  those 
on  the  anterior  part  are  about  one-half,  while  those  on  the  posterior  part  are  one- 
fourth,  as  long  as  the  corresponding  portion  of  the  neck  is  wide.  There  are  six 
subdistinct  lips,  each  with  a  somewhat  forward-pointing,  innervated,  conoid 
papilla.  The  pharynx  is  fairly  well  cutinized,  and  bears  probably  twelve  closely 
approximated  odontia,  forming  a  distinct  circlet  opposite  the  bases  of  the  ceph- 
alic setae;  only  their  points  are  easily  visible.  The  conoid  neck  becomes  more 
decidedly  conoid  near  the  head.  At  first  sight  the  oesophagus  appears  as  if  com- 
posed mainly  of  glands,  which  extend  backward  to  the  cardia.  These  glands  are, 
however,  outside  the  oesophagus  and  empty  near  the  bases  of  the  odontia  by 
means  of  three  or  four  ducts.  At  the  nerve-ring  the  oesophagus  is  three-sevenths, 
and  finally  one-half,  as  wide  as  the  corresponding  part  of  the  neck,  and  ends  pos- 
teriorly in  a  faint,  elongated,  pyrif orm,  valveless  bulb.  The  lining  of  the  oesoph- 
agus is  narrow;  its  musculature  fine.  The  thin-walled  intestine  has  a  faint  lumen 
and  is  set  off  by  a  collum  two-fifths  as  wide  as  the  base  of  the  neck  and  becomes 
at  once  one-half  as  wide  as  the  body.  In  cross-section  it  presents  four  to  five 
at  aulm  I  Ib  set  (kl  sulm  ,.  fcj  ,.,  15_"  9i.  cells.  The  scat- 

Is/  '1.8  '  1.9 '   '  't.6  '  Y*  2-4"tered  granules 
(impll  contained  in  the 

L.       ,6'9.   .10:         7*7   .  '3"-7  a.?-  intestinal   cells 
i./      1.6      1.6         2.  7^Sr1-7  are  of  variable 

size,  the  largest  being  one-fifteenth  as  wide  as 
.fa  ph  the  body.  The  nuclei  of  the  intestinal  cells  are 
one-seventh  to  one-eighth  as  wide  as  the  body 
at  the  base  of  the  neck.  Tail  conoid  from  the 
anus,  but  tapering  faster  near  the  anus.  The 
end  of  the  spinneret  is  in  the  form  of  a  hemi- 
spherical button,  the  three  sectors  of  which  are 

-„  ]!/  L  op  *  *  750  (S"*>  SIHI  eversible.  so  that  the  organ  may  appear  three- 
lobed.  The  ducts  of  the  caudal  glands  are  sep- 
arate, practically  to  the  spinneret  pore.  There  are  about  fifteen  ventrally  sub- 
median,  and  about  ten  dorsally  submedian,  slender,  flexible,  tapering  setae  on 
each  side  of  the  tail  of  the  male.  There  is  a  much  smaller  number  of  setae  on  the 
tail  of  the  female.  The  lateral  fields  are  one-third  as  wide  as  the  body.  The 
granular,  ellipsoidal  renette  cell,  two-thirds  as  long  as  the  body  is  wide  and  two- 
thirds  as  wide  as  long,  is  located  at  a  distance  behind  the  neck  equal  to  the  body 
diameter.  The  obscure,  rather  broad  nerve-ring  is  accompanied  by  distinct 
and  numerous  nerve  cells  of  large  size,  extending  back  to  the  base  of  the  neck. 
The  large,  elevated,  conspicuous  vulva  leads  to  a  conoid,  rather  muscular,  cutin- 
ized vagina  accompanied  by  small,  ellpisoidal  glands.  There  is  a  small  anterior 
branch  to  the  female  sexual  organs,  about  as  long  as  the  body  is  wide.  The  uterus 
extends  back  to  near  the  middle  of  the  body.  The  eggs  are  one  and  one-half  to 
two  times  as  long  as  the  body  is  wide  and  one-fourth  to  one-third  as  wide  as 
long.  Numerous,  granular,  spherical  sperm  cells,  one-fifteenth  as  wide  as  the 
body,  are  abundant  near  the  middle  of  the  body,  disarranging  the  chain  of  eggs 
in  such  a  way  as  to  suggest  the  presence  of  a  spermatheca.  The  broad  ovary 
tapers  gradually,  and  contains  twenty  to  thirty  ova  arranged  single  file.  The 
egg,  just  before  deposition,  lies  opposite  the  vulva,  one-half  of  it  being  in  the 
small  anterior  branch  of  the  uterus.  The  spicula  are  strong,  somewhat  slender, 
sub-uniform,  and  rather  blunt.  Their  proximal  ends  appear  to  lie  ventrad  from 
the  body-axis.  The  two  strong,  well-separated  accessory  pieces  are  one-fourth 


SYNODONTIUM.    DAPTONEMA 


281 


as  long  as  the  spicula.  Their  uniform,  blunt  apophyses  extend  backward  at  an 
angle  of  ninety  degrees  with  the  spicula,  and  are  one-half  as  long  as  the  anal 
body  diameter.  Fifty  to  seventy  equidistant  supplementary  organs,  in  the  form 
of  a  series  of  slight  undulations,  extend  forward  in  front  of  the  anus  a  distance 
three  to  four  times  as  great  as  the  length  of  the  tail.  The  undulations  are  sepa- 
rated from  each  other  by  a  space  about  equal  to  one-fourth  the  body  diameter, 
though  they  become  gradually  a  little  farther  apart  anteriorly.  Thejr  eleva- 
tion is  slight,  and  every  other  undulation  is  opposite  a  granular,  saccate  gland, 
about  one-third  as  wide  as  the  body.  These  glands  form  a  contiguous  series 
and  seem  to  empty  ventrally.  There  is  no  bursa.  The  ejaculatory  duct  is  one- 
third,  and  the  testes  are  one-half,  as  wide  as  the  body,  these  latter  gradually 
tapering  so  that  they  are  narrow  at  the  extremities. 

Habitat:  Sand,  below  Bathing  Beach,  Woods  Hole,  Mass.,  U.  S.  A.  Also 
beach-sand,  Squibnocket,  Martha's  Vineyard,  Mass.,  U.  S.  A.  Flemming  to 
glycerine  jelly.  Fig.  65,  p.  280. 


66.  Daptonemafissidensn.  sp.  w      2-8      3-?  Type  species.    The 

contour  of  the  moderately  thick  cuticle  is  crenate,  the  annules  being  separated 
by  refractive  lines.  Toward  the  head  end  the  $£  cp/f  (/2) 
annules  diminish  in  width  until  they  elude  detec- 
tion. Neck  conoid;  head  rounded.  Here  and 
there  on  the  neck  occur  long,  slender  hairs,  as 
long  as  those  on  the  head,  but  colorless  and  very 
much  more  slender.  Each  of  the  six  lips  is 
strengthened  by  three,  dark-brown,  or  blackish, 
strongly  arcuate,  incurved,  slender,  acute,  cutin- 
ized  ribs  or  teeth.  Lips  capable  of  being 
turned  over  into  the  pharynx  so  as  to  form  a 
flattish,  centrally  indented  dome.  From  the 
head  backward  the  oesophagus  narrows  a  little, 
becoming  two-thirds  as  wide  as  the  correspond- 
ing portion  of  the  neck.  There  is  no  very  dis- 
tinct cardia.  The  rather  thick-walled  intestine 
becomes  at  once  about  half  as  wide  as  the  body, 
and  in  cross-section  presents  about  four  cells. 
The  cells  contain  scattered  brownish  granules, 
of  variable  size,  the  largest  of  which  are  nearly 
as  wide  as  one  of  the  annules  of  the  cuticle.  The 
lumen  of  the  intestine  is  quite  narrow,  and  its 
lining  somewhat  refractive.  Renette  unknown.  ™ 
The  tail  of  the  male  is  conoid  from  the  anus  to 
the  somewhat  blunt  terminus,  which  has  a  plain, 
rather  blunt  spinneret,  armed  with  two  setae 
considerably  longer  than  the  diameter  of  the  ^ 
terminus.  The  caudal  glands  appear  to  be 
located  in  front  of  the  anus.  The  brownish 
spicula  have  been  seen  only  in  dorso-ventral 
view.  The  accessory  pieces  are  curved  distally  ase  m 

in  the  same  way  as  the  spicula,  and  end  in  minute  points.     The  ejaculatory  duct 
is  about  one-third,  the  vas  deferens  about  one-half,  as  wide  as  the  body. 

Habitat:  Larat,  East  Indies;  marine.     In  the  general  form  of  the  neck  and 
pharynx  these  nemas  closely  resemble  Monhystera,  but  the  food  habits    are 


Illl 


282 


ORDER   SYNOUONTIA 


hmoe. 


The 


probably  different,  and  the  structure  of  the  male  differs  materially  from  the 

structure  of  the  male  of  Monhystera,— dark-colored,  punctate,  out-bending  spic- 

ula;    and   two     g  ,.  seHfh(/2\     i  tf  to  (6)     \         Jb\(6) 

testes.   A  very   IT"~i8-~i9 5.1"  "  3.2  V 

similar  marine     1%      !».__»  ""im.     1260. 

species  occurs     »      *2-~  «•         «•       * 

in  the  harbor  at  Portsmouth,  N.  H.,  and  at   ««/ a  13X6) 

Woods  Hole,  Mass.,  U.  S.  A.,  namely  Dapto- 

nema  fimbriatum,  n.  sp.  of  which  the  formulae 

and  the  figure  of  the  head  end  are  given  on 

this  page.    The  head  of  Daptonema  fissidens 

differs  but  slightly  from  that  of  D.  fimbriatum. 

Daptonema  is  manifestly  an  offshoot  of  Monhystera.     Probably 

the  eighteen  refractive  labial  elements  are  ribs  attached  to  a 

thin  membrane.    They  sometimes  appear,  however,  as  if  free  at 

the  extremities,  and  if  so,  would  function  as  combs  in  securing 

the  food,  which  is  probably  combed  or  scraped  from  the  surface 

of  algae  and  other  submarine  objects.     Fig.  660.  p.  281  (fissidens) ; 

Fig.  666  (fimbriatum). 

.6         2.6         4.3        -70." 

67.  Crystallonema  fuscacephalum  n.  sp.  /l-  '•  1-  14 
longer,  cephalic  setae  are  two-jointed.  The  scattered,  inconspicuous  cervical 
setae  are  one-tenth  as  long  as  the  neck  is  wide.  Opposite  the  pharynx  the  head 
contains  dark  brownish  gray  pigment.  The  consistency  of  the  labial  palps  (?) 
remains  undetermined,  that  is  to  say,  it  is  uncertain  whether  they  are  apodontia 
with  an  inward  stroke  and  capable  of  executing  a  firm  grip,  or  whether  they  are 
more  or  less  flabby  palps.  Neck  somewhat  cylindroid,  expanding  a  little  toward 
the  head.  Amphid  with  a  pore  near  the  posterior  margin,  from  which  there 
set  Cph(4]  \  pip  Jb  set  U)  (6 I  ^eads  inward  and  backward  a  narrow  duct 

with  granular  contents.  There  is  a  faint, 
elongated,  more  or  less  pyriform  cardiac 
swelling.  Near  the  nerve-ring  the  oesoph- 
agus  is  one-half,  just  in  front  of  the  cardiac 
swelling  three-fifths,  and  finally  two-thirds, 
as  wide  as  the  corresponding  portion  of  the 
neck.  The  musculature  of  the  oesophagus 
is  rather  coarse  and  colorless.  Cardiac  col- 
lum  two-fifths  as  wide  as  the  body.  The 
intestine  begins  with  a  specially  modified 
segment,  two-thirds  as  long  as  the  corre- 
Itrm  sPonding  body  diameter.  The  intestine, 
rhicli  has  a  somewhat  irregular  lumen, 
1 75Q  gradually  becomes  one-half  to  two-thirds 
as  wide  as  the  body.  The  colorless  gran- 
ules in  the  intestinal  cells  are  scattered  in  groups  and -are  of  variable  size,  the 
largest  granules  being  about  as  wide  as  one  of  the  annules  on  the  neck.  The 
nema  is  strongly  characterized  by  the  presence  of  more  or  less  angular,  doubly 
refractive  crystalline  masses,  having  about  the  same  diameter  in  every  direction, 
and  being  about  one-sixth  as  wide  as  the  body.  The  crystalline  bodies  are  one- 
half  to  one  body-width  apart  and  seem  to  lie  in  the  longitudinal  fields.  The 
conoid  tail  tapers  from  the  anus,  but  at  last  for  a  short  distance  is  more  or  less 


hanoe 


CRYSTALLONEMA,    ZANEMA 


283 


cylindroid  and  one-fifth  as  wide  as  at  the  anus.  There  are  no  caudal  setae. 
The  ellipsoidal  to  prolate  renette  cell  lies  close  behind  the  neck,  and  is  one-half 
as  long  as  the  body  is  wide  and  five-sixths  as  wide  as  long.  The  large,  continuous 
vulva  is  inconspicuous.  The  medium-sized  vagina  extends  two-fifths  the  way 
across  the  body.  There  is  a  posterior  rudimen- 
tary branch  to  the  sexual  organs,  three  times  as 
long  as  the  corresponding  body  diameter.  The 
uterus  is  four  times  as  long  as  the  body  is  wide,  and 
one-sixth  to  one-fifth  as  wide  as  long.  The  elon- 
gated eggs  are  three  times  as  long  as  the  body  is 
wide.  The  relatively  very  small  ovary  contains 
twelve  ova,  which  diminish  rapidly  in  size  toward 
the  blind  end,  and  are  arranged  single  file.  The 
finely-granular,  ripe  ova  are  three  times  as  long 
as  the  body  is  wide,  and  three-fourths  as  wide  as 
long. 

Habitat:  Sand,  below  Bathing  Beach,  Woods 
Hole,  Mass.,  U.  S.  A.  Flemming  to  water.  The 
males  of  this  species,  C.  fvscacephalum,  are 
unknown,  but  the  males  of  two  other  species  are 
known  to  the  writer.  As  these  two  are  structu- 
rally closely  related  to  C.  fuscacephalum,  it  may  be 
assumed  that  the  spicula  of  C.  fuscacephalum  are 
similar  to  those  of  these  others,  one  of  which  is 
Crystallonema  simile  n.  sp.,  Miami,  Fla.,  the  anal 
region  of  the  male  of  which  is  shown  in  the  adjac- 
ent illustration,  together  with  the  dimensions  of 
both  sexes.  Besides  being  smaller,  C.  simile  differs  in  lacking  pigment  at  the 
head  end;  in  having  relatively  slightly  longer  and  more  nearly  equal  cephalic 
setae;  in  having  amphids  relatively  larger, — three-sevenths  as  wide  as  the  head; 
in  having  the  posterior  oesophageal  swelling  almost  indistinguishable;  in  having 
the  preliminary  segment  of  the  intestine  as  long  as  the  body  is  wide,  and  the 
intestine  itself  relatively  a  little  wider,— three-fourths  as  wide  as  the  body. 
Fig.  67a,  p.  282,  C.  fuscacephalum;  Fig.  676,  C.  simile,  n.  sp.,  type  species. 


dnm 


X750 


..?:?... .*.?. 

1.2         1.3 


"-69 
i.3 


-M" 
"1.5" 


68.  Zanema  acanthurum  n. 

Neck  cylindroid. 


Cuticle  naked. 
It  is  possible  that  very  small  or  broken 


(lui 
I  members  of  the  submedian  group  of  cephalic  setae  have 

//ph  escaped  notice,  and  that  there  are  really  three  submedian 
<-/4)  setae  on  each  lip.  There  appear  to  be  six  lips,  but  this 
'  number  is  assumed  largely  on  the  basis  of  the  six  labial 
^P"  appendages,  shown  in  the  illustration.  The  lips  are  rela- 
amph  tively  rather  thick,  and  are  arched  together  over  the 
somewhat  spheroidal  pharynx.  Oesophagus  cylindroid. 
The  intestine  becomes  at  once  three-fourths  as  wide  as 
the  body,  and  appears  to  be  made  up  of  cells  of  large 
size,  so  that  perhaps  only  two  appear  in  the  cross-section. 
The  posterior  lip  of  the  anus  is  slightly  raised;  rectum 
about  as  long  as  the  anal  body  diameter.  The  tail  tapers  from  a  little  in  front 
of  the  anus  and  soon  is  reduced  to  a  diameter  about  half  as  great  as  at  the  base. 
Thence  onward  it  tapers  gently,  so  that  near  the  terminus  it  has  a  diameter  about 


seta// 


284  ORDER    SYNODONTIA 

one-fourth  as  great  as  at  the  anus.  Posterior  two-fifths  of  the  tail  armed  with 
short,  backward-pointing,  arcuate,  acute  thorn-like  setae  to  the  number  of  ten 
on  each  ventrally  submedian  line.  No  caudal  glands.  The  lateral  fields  appear 
to  be  fully  one-third  as  wide  as  the  body.  The  excretory  pore  appears  to  be  con- 
nected with  a  large,  ellipsoidal  ampulla,  nearly  half  as  wide  as  the  neck.  The 
position  of  the  renette  cell  has  not  been  determined.  From  the  depressed  vulva 
the  vagina  leads  slightly  forward.  Beyond  this  fact  little  is  known  concerning 
the  internal  organs.  As  no  traces  of  ova  have  been  seen  behind  the  vulva  it  is 
assumed  that  the  organs  are  asymmetrical. 

Habitat:  Mud,  tide  pool,  low  tide,  Portsmouth,  N.  H.,  U.  S.  A.  The  single 
specimen  examined  contained  numerous  yellowish,  spherical/^crystalline  bodies, 
arranged  in  an  obscurely  double  series,  beginning  at  the  base  of  the  neck  and 
ending  at  the  anus.  Whether  these  are  natural  or  have  been  induced  by  the 
method  of  preservation  remains  to  be  determined.  The  peculiarities  of  the  spe- 
cies justifying  the  establishment  of  a  new  genus  are  as  follows :  (1)  the  formation 
of  the  pharynx  and  of  the  lips  with  their  distinct  forward-pointing  appendages; 
(2)  the  unusual  size  and  form  of  the  amphids;  (3)  the  absence  of  caudal  glands; 
and  (4)  the  peculiar  thorn-like  setae  on  the  tail.  These,  combined  with  the  very 
slender  form,  make  it  difficult  to  refer  this  specimen  to  any  known  genus.  Fig. 
68,  p.  283. 

69a.  Monhystrium  transitans  n.  sp.  Type  species.  Cuticle  naked,  except  for 
the  setae  on  the  head.  Lips  three,  more  or  less  confluent,  thick  and  mobile. 
Pharynx  double;  the  closed  lips  forming  a  narrow  vestibule  reaching  one-third 
the  way  to  the  base  of  the  pharynx.  Anterior  chamber  of  the  pharynx  pyramidal, 
the  posterior  more  of  less  napiform.  The  lips  come  to  a  sharp  edge,  and  are 
stiffened  by  several  refractive  "plates,"  whose  direction  is  radial  but  indefinite, 
as  if  due  to  the  folding  of  a  cutinized  membrane.  Oesophagus  cylindroid,  end- 
ing posteriorly  in  a  pyriform  cardiac  bulb  five-sixths  as  wide  as  the  base  of  the 
neck.  Its  lining  finds  expression  in  three  longitudinal  lines,  occupying  a  space 
equal  to  two-sevenths  the  width  of  the  whole  organ.  Its  musculature  is  rather 
coarse.  There  is  no  cardia.  The  thick-walled  intestine,  which  has  a  distinct, 
refractive  lumen,  is  set  off  from  the  oesophagus  by  a  constriction  one-fourth  as 
wide  as  the  base  of  the  neck,  and  becomes  at  once  three-fourths  as  wide  as  the 
body.  Its  cross-section  shows  two  cells.  In  contour,  it  is  more  or  less  crenate, 
at  least  in  alcoholic  specimens,  because  of  the  pronounced  nature  of  the  intestinal 
cells.  These  latter  contain  numerous  granules  of  rather  uniform  size.  The 
walls  of  the  intestinal  cells  are  refractive.  The  tail  is  at  first  conoid,  then  cylin- 
droid in  the  posterior  two-fifths.  It  tapers  from  in  front  of  the  anus  to  the  almost 
imperceptibly  swollen,  more  or  less  apiculate,  unarmed,  symmetrical  terminus, 
which  presents  a  profile  similar  to  that  of  a  swan's  head.  It  bears  a  simple, 
unarmed,  blunt  spinneret.  Only  two  caudal  glands  are  to  be  seen;  these  are 
broadly  saccate  cells,  forming  a  close  tandem  in  the  anterior  third  of  the  tail. 
The  more  or  less  finely  granular  longitudinal  fields  are  one-third  as  wide  as  the 
body.  The  post-cervical  renette  cell  empties  through  the  excretory  pore  a  little 
in  front  of  the  nerve-ring  by  means  of  a  more  or  less  spherical  ampulla,  and  final 
slender  duct  one-half  as  long  as  the  body  is  wide,  leading  therefrom  to  the 
excretory  pore.  The  vulva  is  large  and  more  or  less  elevated.  The  ellipsoidal 
eggs  are  three-fourths  as  long  as  the  body  is  wide  and  are  deposited  after  seg- 
mentation; it  is  probable  that  the  species  is  viviparous,  or  ovoviviparous.  The 
small  posterior  branch  of  the  sexual  organ  is  one-half  as  long  as  the  body  is  wide. 


MONHYSTRIUM 


285 


rpt 


msuM 


axjlaind 


mnldsl 


The  tapering  ovary  is  at  first  broad,  and  contains  numerous  ova  arranged  for  the 
most  part  single  file.  At  its  blind  end,  it  is  one-eighth  as  wide  as  the  base  of  the 
neck.  At  their  widest  part,  that  is,  near  the  middle,  the  spicula  are  one-sixth  as 
wide  as  the  corresponding  portion  of  the  body.  They  taper  to  a  rather  blunt  point, 
and  present  a  faint,  stiffening  element.  These  ^int  amnh  wfsn/m 

colorless,  rather  frail  spicula  appear  to  have 
their  proximal  ends  somewhat  dorsad  from  the 
body-axis.  There  is  a  faint,  frail,  slender, 
arcuate  accessory  piece,  lying  parallel  to  the 

spicula,  probably  consisting  merely  of  a  differ-  or  ""  '  "  /////.'/// 

entiation  of  the  lining  of  the  cloaca.  Obscure 
papillae  occur  on  the  middle  part  of  the  tail,  msc silbm .: 
near  the  place  where  it  suddenly  diminishes  a 
little  in  diameter.  These  are  probably  as  fol- 
lows: one  ventrally  submedian  pair  opposite 
the  middle  of  the  spicula;  three  ventrally  sub- 
median  pairs,  one  of  them  nearly  anal,  the 
other  two  at  the  beginning  of  the  middle  third, 
and  occurring  one  in  front  of  the  other;  one 
dorsally  submedian  pair.  The  large  spermato- 
cytes  in  the  testes  are  three-fourths  to  two- 
thirds  as  wide  as  the  body.  That  portion  of 
the  testis,  containing  them  is  correspondingly 
wide,  but  the  testis  tapers  so  as  finally  to  be 
only  about  one-fourth  as  wide  as  the  body. 

Habitat:  Gill-chambers  of  the  Land  Crab, 
G.  ruricola,  Jamaica.    Coll.,  Dr.  C.  B.  Wilson, 
Westfield,   Mass.     Described   from   more    or 
less  shrunken  alcoholic  specimens,  mounted  in 
balsam  and  in  glycerine  jelly.     May  be  looked  lumoe  , 
upon  as  a  transitional  form  between  a  free-   1.4       10.6       20.      **-&       90. <     )  .9  „ 
living  and  parasitic  state.     Hence,  the  specific   3'5       /4'J 

name    transitans.     While    much    reduced    and  11 "J M «^_ ^ >  83.. 

flabby,   the   cephalic   setae  still   exist.    Very 

few  parasitic  nemas  possess  cephalic  setae.     Fig.  69a. 

b.  Monhystrium  wilsoni  (Baylis).  Very  narrow  wings  extend  from  the  base 
of  the  neck  to  near  the  anus.  Each  wing  is  expressed  as  a  double  line.  Eight 
to  twelve  longitudinal  striations  occur  on  each  submedian  field.  The  longi- 
tudinal striae  do  not  anastomose,  and  seem  to  be  in  the  outer  cuticle.  Lips  con- 
fluent, elastic,  closing  to  a  small  central  pore.  Pharynx  of  two  chambers;  the 
anterior,  pyramidal,  the  posterior  appearing  roughly  napiform  in  profile,  but 
really  three-sided  as  shown  in  the  illustration.  The  distinct,  refractive  lining 
becomes  rapidly  thicker  in  the  posterior  half  of  the  second  chamber.  About 
eighteen  duplex  radial  refractive  ribs  of  small  size  occur  in  the  anterior  chamber, 
somewhat  as  in  Cyatholaimus;  i.e.,  there  are  about  six  refractive  radial  markings 
on  each  of  the  three  lips.  These  have  a  rather  definite  duplex  outer  end,  or  con- 
tour, but  are  not  so  definite  as  the  "rods"  of  Cyatholaimus,  being  more  like 
folds.  Neck  conoid;  head  convex-conoid.  The  cylindroid  oesophagus  near  the 
nerve-ring  is  two-fifths,  just  in  front  of  the  pyriform  cardiac  swelling  two-thirds, 


X1000 


286  ORDER    SYNODONTIA 

finally  two-thirds,  as  wide  as  the  corresponding  part  of  the  neck.  There  are  no 
oesophageal  bulbs,  but  there  is  a  pyriform  anterior  segment  of  the  intestine, 
set  off  on  both  sides  by  a  distinct  constriction,  in  some  ways  resembling  a  cardiac 
bulb.  This  pseudo-bulb  is  three-fourths  as  wide  as  the  corresponding  portion  of 
the  body,  as  measured  in  alcoholic  specimens.  The  lining  of  the  oesophagus  is 
a  prominent  feature,  and  its  optical  expression  consists  in  three  refractive  lines, 
occupying  a  space  one-fourth  as  wide  as  the  entire  organ.  The  oesophageal 
musculature  is  coarse.  At  the  cardiac  constriction  there  are  three  elements, 
questionably  glands,  each  one-third  as  wide  as  the  corresponding  portion  of  the 
body.  There  is  no  cardia.  The  thick-walled  intestine  has  a  very  distinct  refrac- 
tive lumen  and  soon  becomes  five-sixths  as  wide  as  the  body.  The  cells  compos- 
ing the  intestine  are  about  twice  as  long  as  he  body  is  wide,  and  are  so 
arranged  that  each  cross-section  presents  practically  only  two  of  them.  These 
cells  are  packed  with  exceedingly  fine  granules  of  more  or  less  uniform  size.  The 
tail  is  first  conoid,  then  cylindroid  in  the  posterior  half.  It  tapers  from  in  front 
of  the  anus;  the  terminus  has  a  contour  more  or  less  resembling  that  of  a  swan's 
head.  The  simple,  unarmed,  symmetrical,  blunt  spinneret  is  half  as  wide  as  the 
terminus.  The  three,  broadly  saccate  caudal  glands  form  a  close  tandem  in  the 
anterior  fourth  of  the  tail.  Their  ducts  and  ampullae  are  distinct.  There  are 
no  caudal  setae.  The  tail,  like  the  body,  is  naked.  The  elongated  renette  cell 
lies  two  to  four  body-widths  behind  the  neck,  and  empties  through  a  wide  duct 
separated  from  the  ampulla  by  a  constriction;  the  ampulla  is  one-fourth  as  wide 
as  the  corresponding  portion  of  the  neck,  and  empties  through  a  pore  located 
half-way  back  to  the  nerve-ring.  The  nerve-ring  is  accompanied  by  distinct 
nerve-cells  arranged  in  groups.  From  the  somewhat  large,  more  or  less  conspicu- 
ous vulva,  the  large,  rather  muscular,  cutinized  vagina  leads  half-way  across  the 
body.  The  straight  uterus  is  about  fourteen  times  as  long  as  the  body  is  wide, 
and  contains  ellipsoidal  eggs,  each  about  as  long  as  the  body  is  wide,  which  are 
deposited  after  segmentation  begins,— in  fact,  the  species  may  be  viviparous. 
Fully-formed  embryos  occur  in  the  eggs  near  the  vulva.  Spermatozoa,  half  as 
wide  as  the  body  of  the  female,  and  with  strong  refractive  nuclei,  occur  in  the 
uterus.  There  is  a  rather  narrow,  ventral  posterior  rudimentary  part  to  the 
female  sexual  organ,  about  one  and  one-half  times  as  long  as  the  corresponding 
portion  of  the  body  is  wide.  The  ovary  is  nearly  cylindroid,  but  tapers  slightly, 
and  contains  numerous  ova  arranged  single  file.  Toward  its  blind  end,  it  sud- 
denly narrows,  and  is  reflexed,  or  thrown  into  an  "S"  form,  in  a  space  one  to  two 
times  as  long  as  the  body  is  wide;  here  it  is  only  one-sixth  as  wide  as  the  body. 
The  rather  frail,  somewhat  simple,  rather  slender,  subacute  spicula  are  one  and 
one-half  times  as  long  as  the  anal  body  diameter.  At  their  widest  part  near  the 
middle,  they  are  about  one-sixth  as  wide  as  the  corresponding  portion  of  the  body. 
Their  proximal  ends  appear  to  lie  dorsad  from  the  body-axis.  The  single,  frail, 
very  slender,  more  or  less  arcuate,  accessory  piece  is  somewhat  removed  from  the 
spicula,  at  least  from  the  refractive  part.  Its  proximal  extremity  lies  dorsad 
from  the  body-axis.  There  are  no  supplementary  organs.  About  ten  pairs  of 
papillae  occur  on  the  tail  of  the  male.  These  are  very  inconspicuous  and  are 
arranged  as  follows:  one  ventral,  single,  and  two  submedian  pairs  just  in- front 
of  the  anus;  third,  fourth,  fifth  and  sixth  pairs  behind  the  anus,  opposite  the  two 
anterior  caudal  glands;  seventh  and  eighth,  lateral,  opposite  the  posterior  caudal 
gland;  ninth  and  tenth  farther  back,  not  so  close  together,  averaging  about  twice 
as  far  from  the  anus,  as  the  seventh  and  eighth.  There  is  a  rudimentary  bursa; 
i.e.,  there  are  submedian  longitudinal  elevations  of  considerable  magnitude 


MONHYSTRIUM,    ASYMMETBELLA 


287 


beginning  some  distance  in  front  of  the  anus  and  extending  on  to  the  tail  to  a 
point  opposite  the  posterior  caudal  gland.  Most  of  the  papillae  described  occur 
on  the  ventral  surface  of  these  welt-like  elevations.  A  cross-section  taken  near 
the  anus  clearly  discloses  these  well-developed  organs.  The  ejaculatory  duct  is 
one-fourth,  the  vas  deferens  one-fourth,  the  testis  two-thirds,  as  wide  as  the 
corresponding  portion  of  the  body.  Toward  its  blind  end,  however,  the  testis 
tapers  so  as  to  be  only  one-eighth  as  wide  as  the  corresponding  portion  of  the 
body.  Spermatocytes,  occupying  a  considerable  portion  of  the  length  of  the 
testis,  are  one-half  to  two-thirds  as  wide  as  the  body,  so  that  the  testis  bears 
considerable  resemblance  to  an  ovary.  The/inset  hblbsubm  pfllb  set  lot  setsdm 
deceptive  appearance  created  by  these  large 
spermatocytes  might  easily  lead  to  the  con-nrpffl/ 
elusion  that  the  males  are  hermaphrodites. 

Habitat:  Found  with  the  preceding. 

One  is  inclined  to  suggest  that  this  Mon-  ».. 

hystrium  also  represents  a  transitional  form 
from  a  free-living  to  a  parasitic  condition. 
A  careful  study  of  such  forms  is  destined  to 
throw  much  light  on  the  relationship  between 
the  Laimia  and  Alaimia. 

Although  bearing  considerable  resemblance 
to  Monhystera,  this  species  and  its  close  rela- 
tive just  described  seem  to  make  a  new  genus 
desirable  for  their  reception.  The  distin- 
guishing  differences  may  be  listed  as  follows: 
(1)  In  Monhystrium,  the  pharynx  is  a  double 
chamber;  moreover,  the  anterior  chamber 
has  a  distinctly  radiated  structure,  more  eas- 
ily  seen  if  the  specimen  is  viewed  slightly 
obliquely  instead  of  laterally,  as  shown  in  the 
illustration.  These  radial  elements  are  stiff- 
ening factors  enabling  the  lips  to  bite  more 
efficiently.  The  margins  of  the  lips  are  sharp- 
cutting  edges,  as  is  clearly  shown  in  the  profile 
view  in  the  illustration.  Further  study  is  necessary  to  determine  whether  these 
organs  are  odontia  or  onchia.  (2)  The  pseudo-bulb,  which  is  not  common  in 
Monhystera.  (3)  Monhystrium  is  ovoviviparous  or  viviparous.  (4)  There  is 
a  pronounced  renette.  (5)  There  are  no  cephalic  setae  or  the  setae  are  very 
weakly  developed.  (6)  The  species  is  presumably  carnivorous;  the  more  typical 
Monhysteras,  perhaps  all,  are  vegetarian. 

Larvae  removed  fron  the  uterus  of  alcoholic  specimens  present  differences 
from  the  adults  as  follows:  (1)  The  amphids  are  farther  back.  (2)  The  pharynx 
is  tubular,  and  not  in  two  parts.  (3)  The  head  is  more  tapering.  (4)  The  spin- 
neret is  not  so  well  defined.  (5)  No  wings  were  seen.  (6)  The  pseudo-bulb  is 
less  conspicuous.  Fig.  696,  on  this  page.  Syn.  Monhystera  wilsoni  Baylis. 

1.3      14.         27.        '"'62»'"        95-    >2 

70.  Asymmetrella  glabra  n.  sp.  U4  *-6  E-3  1-8  '•'  '  "  Lips  three,  dis- 
tinct, unequal,  flat,  thin.  Pharynx  with  a  peculiar  dorsal  onchium,  bent  inward 
at  right  angles  at  the  apex.  Oesophagus  surrounding  the  posterior  two-fifths  of 
the  pharynx  in  the  form  of  three,  somewhat  finger-shaped  processes.  Wall  of 
the  pharynx  fairly  well  cutinized,  especially  near  the  lips  on  the  dorsal  side, 


288  ORDER  SYNODONTIA,  ORDER  SYNONCHIA 

where  it  bends  inward  and  forms  an  elbowed  lip,  giving  to  the  front  of  the  head 
an  asymmetrical  appearance;  hence,  the  generic  name.  Neck  cylindroid  posteri- 
orly, convex-conoid  anteriorly.  Amphids  faint.  At  the  base  of  the  pharynx 
there  are  three  spherical  collections  of  black,  loosely-placed  granules  (ocelli?), 
one  collection  dorsal  and  two  submedian,  the  dorsal  collection  being  the  least 
pronounced.  The  cylindroid  oesophagus  at  the  nerve-ring  is  one-third,  and  fi- 
nally is  one-half,  as  wide  as  the  corresponding  portion  of  the  neck;  it  has  an  indis- 
tinct lining,  and  a  fine,  colorless  musculature.  There  is  a  more  or  less  hemi- 
spherical cardia,  three-fifths  as  wide  as  the  base  of  the  neck.  The  thick-walled 
intestine,  which  is  set  off  by  a  constriction  one-half  as  wide  as  the  base  of  the 
neck,  becomes  at  once  three-fourths  as  wide  as  the  body.  It  has  a  faint  lumen, 
and  its  cross-section  exhibits  about  four  cells.  In  all  parts  of  the  intestine  the 
cell  walls  are  rather  distinct  and  optically  give  rise  to  a  network 
effect.  From  the  more  or  less  continuous  anus  the  prominent, 
cutinized  rectum  extends  inward  a  distance  three-fourths  as  great 
as  the  anal  body  diameter.  The  rather  numerous,  more  or  less 
yellowish  granules  contained  in  the  cells  of  the  intestine  are  of 
Invariable  size,  the  .largest  being  about  one-thirty-fifth  as  wide  as 
the  body.  They  are  so  arranged  as  to  give  rise  to  a  more  or 
less  distinct  tessellation.  The  lateral  fields  are  one-fourth 
as  wide  as  the  body.  The  tail  tapers  from  the  anus,  and  is  at  first  conoid,  and 
then  convex-conoid  in  the  posterior  eighth.  It  is  arcuate  to  the  unarmed,  more 
or  less  symmetrical  terminus.  There  is  a  conoid,  symmetrical  spinneret.  In  it 
a  compound  ampulla  is  apparent.  Renette  unknown.  The  female  sexual  organs 
are  probably  double  and  symmetrically  placed. 

Habitat:  Marine  tap  water,  laboratory,  Woods  Hole,  Mass.,  U.  S.  A.  Flem- 
ming  to  glycerine  jelly.  Fig.  70. 

VIII.  Order  Synonchia 

71.  Tripylium  carcinicolum  (Baylis).  Cuticle  naked.  Cephalic  setae  papil- 
loid.  Wall  of  the  pharynx  fairly  thick  and  refractive,  and  curved  inward  on  the 
inner  surface  of  each  pair  of  lips  so  as  to  form  three  120°  biting  organs,  which 
close  together  as  shown  in  the  illustration.  Pharynx  cylindroid.  Neck  cylin- 
droid posteriorly,  conoid  anteriorly.  Oesophagus  cylindroid,  its  lining  a  trifle 
stronger  behind  the  pharynx  for  a  distance  equal  to  the  length  of  the  pharynx. 
The  anterior  portion  of  the  intestine  is  altered  so  as  to  produce  the  effect 
of  a  pyriform  bulb  three-fourths  as  wide  as  the  base  of  the  neck,  set  off  on 
both  sides  by  a  constriction.  At  the  nerve-ring,  the  oesophagus  is  two-thirds, 
and  finally  three-fifths,  as  wide  as  the  corresponding  part  of  the  neck.  The  lin- 
ing of  the  oesophagus  finds  optical  expression  in  three  refractive  lines,  occupying 
two-fifths  of  the  width  of  the  organ.  There  is  no  cardia.  What  appear  to  be 
glandular  cells  occur  opposite  the  cardiac  constriction,— two,  one  on  each  side, 
each  ellipsoidal  and  half  as  wide  as  the  neck,  finely  granular  and  with  a  promi- 
nent nucleus.  The  thick-walled  intestine  has  a  distinct,  refractive,  more  or  less 
zig-zag  lumen,  and  becomes  at  once  three-fourths  as  wide  as  the  body;  in  cross- 
section  it  presents  two  cells.  The  cardiac  collum  is  one-fourth  as  wide  as  the 
neck.  From  the  more  or  less  continuous  anus,  the  cutinized  rectum  extends  a 
distance  equal  to  the  length  of  the  anal  body  diameter.  Fine  uniform  granules 
pack  the  cells  of  the  intestine;  there  is  a  faint  tessellated  effect  due  to  the  refrac- 
tive nature  of  the  cell  walls.  From  in  front  of  the  anus,  the  straight  tail  is  first 


TRIPYLIUM,    XYALA 


289 


xtaim 


conoid,  then  cylindroid  in  the  posterior  two-fifths,  where  it  is  one-eighth  as 
wide  as  at  the  base.  Terminus  apiculate,  bearing  a  simple,  symmetrical  spin- 
neret. The  three  broadly-saccate  caudal  glands  are  packed  into  the  anterior 
two-fifths  of  the  tail,  and  empty  by  means  of  separate  ducts.  Three  pairs  of 
conoid,  subacute,  ventrally  submedian  papilloid  setae  occur  on  the  tail  of  the 
female,  one  pair  near  the  anus,  one  near  the  middle  of  the  tail  and  one  at  the  begin- 
ning of  the  posterior  fourth.  Midway  on  the  tail  there  is  a  dorsally  submedian 
pair  of  setae.  The  finely-granular  lateral  fields  are  half  as  wide  as  the  body. 
There  appears  to  be  an  elongated  renette  cell  one  body-diameter  behind  the 
neck;  it  is  one-fifth  as  wide  as  the  body.  From  « 
the  large,  conspicuous,  elevated  vulva,  the 
vagina,  also  large,  extends  inward  half  way  across  j^y^ 
the  body.  Its  wall  is  cutinized.  There  is  no 
posterior  vestigial  portion  to  the  sexual  organ. 
The  straight  uterus  contains  twelve  or  more 
already  liberated  embryos.  Ova  are  arranged 
single  file.  The  simple,  rather  frail,  slender, 
uniform,  acute  spicula  are  arcuate  distally. 
They  are  three-fourths  as  long  as  the  tail,  and  at 
their  widest,  about  one-tenth  as  wide  as  the  cor-  .>. 
responding  portion  of  the  body.  Their  proximal 
ends  seem  to  lie  more  or  less  dorsad  from  the 
body-axis.  The  simple,  frail,  very  slender,  arcu- 
ate accessory  piece  is  more  or  less  obscure  in  alco- 
holic specimens.  It  lies  parallel  to  the  spicula 
and  its  proximal  end  appears  to  be  dorsad  from 
the  body-axis.  There  are  three  pairs  of  very  flat, 
conoid,  innervated,  inconspicuous,  nearly  ven- 
tral papillae  on  the  tail,  one  at  the  beginning  of 
the  fourth  fifth,  and  two  at  equal  distances 
between  it  and  the  anus.  The  ejaculatory  duct 
is  one-third,  the  testis  two-thirds,  as  wide  as 
the  body.  Only  the  narrow  blind  end  of  the 

testis,  for  a  distance  equal  to  one  body-diameter,  \-^ j^ ^ — ~li — ^frf"*  1-1" 

is  reflexed.     In  one  specimen,  the  spicula  were 

more  or  less  compound.  jj| ^3 — TT~~ — ^i Tz~>  0-9  ™ 

Habitat:  Found  in  the  gills  of  the  Land  Crabs, 

Gecarcinus  ruricola  and  Cardisoma  guanhumi,  Jamaica.  Collected  by  Dr.  Chas. 
B.  Wilson,  Westfield,  Mass.  This  genus  differs  from  Monhystera  as  follows:  (1) 
Male  has  caudal  papillae;  (2)  Has  a  cardiac  bulb  or  pseudo-bulb;  (3)  Is  vivip- 
arous; (4)  Is  parasitic  in  crabs;  (5)  Has  three  biting  edges  to  the  segments  of 
the  pharynx.  Fig.  71.  Syn.  Monhystera  carcinicola  Baylis. 

72.  Xyala  striata  n.  sp.  Cuticle  with  numerous  wings,  especially  anteriorly, 
where  there  are  sixteen,  increasing  to  about  thirty-two  on  the  head;  behind  the 
vulva  the  number  is  twelve,  at  the  terminus  four.  Contour  dentate.  There  are 
a  few  cervical  setae,  about  as  long  as  the  body  is  wide,  occurring  in  groups  of 
four;  no  somatic  setae.  Lips  thick,  armed  with  three,  mandible-like  odontia, 
or  onchia,  somewhat  flap-shaped,  and  apparently  very  mobile.  Pharynx  simple, 
regular,  more  or  less  conoid,  large  and  long,  three-fourths  as  wide  as  the  head, 
having  the  form  of  a  deep  cup.  There  is  a  distinct,  transverse,  cutinized  raised 


290 


ORDER   SYNONCHIA 


circle  on  the  inner  wall  of  the  pharynx,  dividing  it  into  two  more  or  less  distinct 
parts;  nevertheless,  the  inner  contour  of  the  pharynx  is  rather  regular  on  the 
whole.  Neck  cylindroid.  Oesophagus  plain,  except  that  there  is  a  pyriform 
bulb  surrounding  the  pharynx,  tapering  gradually  into  the  oesophagus,  which  is 
at  first  two-thirds,  at  the  nerve-ring  one-half,  and  finally  two-fifths,  as  wide  as 
the  corresponding  portion  of  the  neck.  There  is  a  more  or  less  cylindroid  cardia 
one-third  as  wide  as  the  base  of  the  neck.  The  thick-walled  intestine  has  a 
distinct  lumen,  and  becomes  at  once  two-thirds  as  wide  as  the  body.  Cardiac 
kcollum  one-half  as  wide  as  the  body.  The  scattered,  rather  uniform  yellow 
seHphestrW  mnd  \lat  setcphJntr(6>  £— -'f--^ ---^| -— -^ _->i.4..  granules, 

found  in  the 

LI      v-A—25.  _      -*-'  __.9i.  ?18      intestinal 
1-4      ll7      1-8         2'2    ~* 1>6  cells,  are  less 

than  half  as  wide  as  one  of  the  annules. 
From  the  continuous  anus  the  more  or 
less  cutinized  rectum  extends  inward  a 
distance  hardly  as  great  as  the  anal  body 
diameter.  The  conoid  tail  tapers  from 
the  anus,  near  which,  in  the  anterior  third 
of  the  tail,  the  three  ellipsoidal,  caudal 
glands  lie  in  a  close  tandem.  There  are 
very  few,  inconspicuous,  slender,  taper- 
ing, acute,  dorsally  submedian  caudal 
setae.  Renette  unknown.  The  nerve- 
ring  surrounds  the  oesophagus  obliquely  and  is  accompanied  by  obscure  nerve 
cells.  From  the  large,  conspicuous  vulva,  the  large,  tubular,  muscular,  cutin- 
ized vagina  extends  forward  a  distance  equal  to  the  width  of  the  body,  where  it 
joins  the  straight  uterus,  which  is  six  times  as  long  as  the  body  is  wide  and  con- 
tains eggs  two  and  one-half  times  as  long  as  the  body  is  wide,  and  one-third  as 
wide  as  long, — if  one  may  judge  the  size  of  the  eggs  from  that  of  a  full-grown 
ovum.  There  is  a  spermatheca  extending  forward  a  distance  five  to  six  times 
greater  than  the  body  diameter,  the  extent  of  which  is  plainly  indicated  by  the 
definite  contour  of  its  blind  end.  The  rather  narrow,  tapering  ovary  contains 
about  twenty  ova  arranged  single  file.  The  spicula  are  slender,  uniform,  and 
acute.  Their  spherical  proximal  ends  appear  to  lie  dorsad  from  the  body-axis. 
The  two,  separate,  slender,  acute,  strong  accessory  pieces  have  proximal  parts 
that  appear  to  envelop  the  spicula.  There  are  no  pre-anal  ventral  supplemen- 
tary organs,  or  special  papillae.  The  ejaculatory  duct  is  one-third  as  wide  as  the 
body.  The  narrow,  cylindroid  testes  finally  taper  to  a  width  two-fifths  as  great 
as  that  of  the  body. 

Habitat:  Eel-grass,  Woods  Hole,  Mass.;  also  Belmar,  New  Jersey,  U.  S.  A. 
Sublimate  to  balsam.    Fig.  72. 


X750 


97.2 

>  1.3  ., 

There 


7-5  .  15-  61 

...............  •- 

73.  Synonchium  obtusum  n.   sp.  ^      3>5  '  3-6  Tere  are  no 

wings.  On  the  lateral  fields,  which  are  about  one-fourth  as  wide  as  the  body, 
the  secondary  elements  of  the  annules  become  scattered  and  coarser,  and  oval 
or  elongated  in  contour.  There  are  two  laterally  submedian,  irregular  rows  of 
pores,  one  to  two  times  as  wide  as  the  annules,  lying  along  the  margins  of  the  lat- 
eral fields,  and  separated  from  each  other  transversely  by  a  distance  about  equal 
to  one-fourth  the  width  of  the  body;  measured  in  a  longitudinal  direction,  the 
distances  between  the  pores  are  about  the  same,  but  somewhat  irregular.  These 
pores  have  a  special  arrangement  on  the  tail.  (See  illustration.)  Neck  cylin- 


SYNONCHIUM.    GAMMANEMA 


291 


droid;  oesophagus  somewhat  cylindroid,  but  presenting  a  more  or  less  spheroidal 
bulb  about  the  mandibles.  At  the  base  of  the  neck,  the  oesophagus  is  two-thirds 
as  wide  as  the  corresponding  portion  of  the  body.  Its  lining  is  more  or  less  dis- 
tinct; its  musculature  colorless.  The  rather  thick-walled  intestine  has  a  faint 
lumen,  and  becomes  at  once  five-sixths  as  wide  as  the  body.  Throughout  the 


X750 

body  under  the  cuticle,  there  are  coarsely  granular,  spherical  organs  one-fourth 
to  one-third  as  wide  as  the  body,  located  in  the  lateral  fields,  and  separated 
from  each  other  longitudinally  by  a  distance  about  equal  to  the  body  diameter. 
It  is  probable  that  the  female  organs  are  double,  and  symmetrically  reflexed. 


. 

2.7      3.1  :    s.i         3.1  "^a-s  Apparently  there  are  only  two  small  supple- 

mentary organs  in  front  of  the  anus.  (See  illustration,  sup.)  Resembles  Eno- 
plus,  from  which  it  is  distinguishable,  however,  by  the  form  of  the  spicula,  and 
other  organs  of  the  male,  as  well  as  by  the  form  of  the  amphids. 

Habitat:  Seaweed,   drifted  ashore,  Ocean  Beach,  Miami,  Florida,  U.  S.  A. 
Fig.  73. 

74.  Gammanema  ferox  n.  sp.    Neck  cylindroid.     Cuticle  naked,  except  for  the 
setae  on  the  head.     Lips  joined  by  a  membrane, 

ii'  '  3?i'='  '  ii  .....  3.2  '  '  '  2/5'>2'5"*  variously   armed   as  shown   in  the   illustration. 
Probably  the  twelve  "spatulate"  appendages  are 

Ii'  '  Vg'''  ''I''!'  '  '  '~3'1'  =-;-4^'9'>'2-5"  sensory  organs,  if  one  may  judge  by  their  form 
and  position.     The  pharyngeal  bulb   contains 

three  "apophyses,"  each  carrying  near  its  summit  an  inward-pointing,  acute 
onchium,  —  or  perhaps  it  would  be  better  to  say,  each  of  the  three  strong  ribs  of 


292 


ORDER   SYNONCHIA 


the  posterior  portion  of  the  pharynx  bears  one  of  these  onchia.  The  oesophagus 
gradually  diminishes  so  that  at  no  great  distance  behind  the  head  it  is  but  little 
more  than  half  as  wide  as  the  neck,  and  continues  thus  throughout.  There  is  a  some- 
what small,  hemispherical  cardia  about  one-third  as  wide  as  the  base  of  the  neck. 
The  intestine  becomes  at  once  about  three-fourths  as  wide  as  the  body.  In  cross- 
section  it  presents  four  to  six  cells,  manifestly  of  two  different  kinds,  one  of  which, 
a  minority,  is  much  more  distinctly  granular  than  the  other  and  is  more  numer- 
ous in  the  anterior  portion  of  the  intestine  than  in  the  posterior.  The  limits  of 
each  cell,  of  whichever  kind,  are  rather  clearly  marked  on  account  of  the  refrac- 
tive nature  of  the  cell-walls.  The  cells  are  packed  with  a  multitude  of  fine, 
nearly  colorless  granules.  The  anus  is  prominently  raised;  the  rectum  is  as  long 
as  the  anal  body  diameter.  The  tail  is  conoid  to  the  convex-conoid  terminus, 
which  forms  a  convex-conoid,  somewhat  truncate  spinneret  of  large  size,  in  which 
is  the  group  of  large  ampullae  of  the  caudal  glands,  which  nearly  fills  the  terminus, 
its  diameter  being  about  half  as  great  as  that  of  the  base  of  the  tail.  The  large 
caudal  glands  are  located  in  a  close  tandem  just  behind  the  anus,  in  the  anterior 
two-thirds  of  the  tail.  The  lateral  fields  are  fully  one-third  as  wide  as  the  body, 
and  contain  cells  of  unusual  size, — of  such  a  width  as  to  reach  nearly  across  the 
fields  themselves.  These  cells  are  not  contiguous,  and  there  are  found  with 
them  in  the  lateral  field  cells  of  small  size.  Renette  unknown.  From  the  ele- 
vated vulva  the  vagina  leads  inward  half  way  across  the  body,  where  it  joins  the 
single  uterus,  which  extends  backward.  The  ovary  reaches  about  half  way  back 

to  the  vulva  and  contains 
six  to  twelve  developing 
ova,  of  which  the  larger 
ph  are  arranged  single  file. 
The  eggs  appear  to  be 
elongated,  somewhat 
murph  longer  than  the  body  is 
wide  and  about  one-third 
as  wide  as  long.  The  anus 
of  the  male  is  prominently 
raised.  In  front  of  it  there 
is  a  ventral  series  of  sup- 
plementary organs  occu- 
pying a  space  equal  to  six 
to  eight  body-diameters. 
The  hindermost  of  these 
organs  is  located  opposite 
750  the  posterior  part  of  the 
spicula,  and  the  penultimate  opposite  the  middle  of  the  spicula,  and  the  third 
from  the  last  nearly  opposite  the  proximal  ends  of  the  spicula;  the  series  contin- 
ues along  the  ventral  line  with  a  somewhat  equidistant  arrangement,  the  total 
number  of  supplements  being  at  least  sixteen.  Each  supplement  is  a  somewhat 
narrow  cutinized  structure  of  small  size,  extending  outward  and  backward,  and 
its  distal  extremity  is  capable  of  being  exserted.  These  organs  are  not  very  con- 
spicuous. A  few  submedian  setae  are  seen  near  the  anus,  one  pair  opposite  the 
distal  parts  of  the  spicula,  and  one  or  two  on  the  bulky  portion  of  the  tail.  The 
slender,  uniform  spicula  have  their  proximal  ends  located  opposite  the  body- 
axis.  The  width  of  the  spicula  is  not  much  greater  than  that  of  the  surrounding 
nuclei,— in  other  words,  the  spicula  are  quite  slender.  They  are  accompanied 


GAMMANEMA,    TROGOLAIMUS 


293 


by  obscure  accessory  pieces.  The  ejaculatory  duct  is  about  one-third  as  wide  as 
the  body,  the  vas  deferens  about  half.  The  testes  are  unusually  short  and  broad, 
only  about  four  to  six  body-diameters  long,  and  are,  at  their  broadest,  two- 
thirds  as  wide  as  the  body;  they  taper  rapidly  to  the  blind  ends,  which  are  only 
about  one-fourth  as  wide  as  the  body. 

Habitat:  Marine;  coral  sand.  New  Hebrides.     Sublimate  to  balsam.     Fig.  74 
p.  292. 


lb(6) 


ndm 


75.  Trogolaimus  uniformis  n.  sp.  '^  M  :  ^  '  i~«~f^~~i~«  '  Lip-region 
divided  into  twelve  parts,  readily  distinguishable,  though  not  cutinized.  The 
broadly  cup-shaped  anterior  por- 
tion of  the  pharynx  is  that  part 
referred  to  in  the  formula.  From 
its  rather  flattish  base  three 
apophyses  extend  backward  close 
together,  near  the  axis  of  the ' 
head,  a  distance  about  equal  to 
the  depth  of  the  open  portion  of  asc- 
the  pharynx,  thus  adding  a  second 
chamber.  Each  of  these  apophy-  «- 
ses  has  a  small,  inward-pointing 
onchium  at  its  apex.  These  &$ 
onchia  meet  together  and  cross  at  the  middle  of  the  floor  of  the  anterior  portion 
of  the  pharynx.  As  usual,  the  apophyses  serve  for  the  attachment  of  muscles, 
and  all  that  portion  of  the  pharyngeal  bulb  in  front  of  the  bases  of  the  apophyses 
is  different  in  character  from  the  wall  of  the  oesophagus,  being  more  completely 
fibrous  and  destitute  of  the  large  nuclei  that  occur  in  the  oesophageal  muscula- 
ture. The  oesophagus  continues  with  the  same  diameter  until  after  it  passes 
through  the  nerve  ring,  when  it  begins  to  expand  gradually,  so  that  finally  it 
is  more  than  half  as  wide  as  the  base  of  the  neck.  In  optical  section  the  lining 
of  the  oesophagus  appears  wavy.  There  is  no  distinct  cardia.  The  intest  ne, 
which  is  separated  from  the  oesophagus  by  a  deep  constriction,  becomes  at  once 
about  three-fourths  as  wide  as  the  body.  Its  cross-section  probably  presents 
two  to  four  cells.  These  contain  a  multitude  of  minute,  evenly  distributed 
granules.  The  walls  of  the  cells  are  refractive.  The  lateral  fields  are  about  two- 
fifths  as  wide  as  the  body,  and  appear  to  be  composed  of  two  rows  of  cells. 
Renette  unknown.  The  tail  of  the  male  is  conoid  from  the  prominently  raised 
anus.  It  diminishes  in  diameter  rather  slowly  until  near  the  end.  The  diam- 
eter of  the  base  of  the  spinneret  is  about  one-sixth  to  one-eighth  as  great  as  that 
of  the  base  of  the  tail.  The  caudal  glands  appear  to  be  located  in  front  of  the 
anus.  In  Cyatholaimus,  with  which  Trogolaimus  may  be  compared,  it  is  usually 
easy  to  discover  the  ventral  gland  and  excretory  pore.  So  far  these  have  not  been 
seen  in  the  present  species.  The  following  is  a  description  of  the  tail  of  a  young 
female :  The  posterior  lip  of  the  anus  is  distinctly  raised  and  rather  broad.  The 
rectum  is  somewhat  longer  than  the  anal  body-diameter.  The  tail  is  cylindrical 
to  the  rounded  or  conoid-hemispherical  terminus,  which  ends  in  a  somewhat 
cylindrical  spinneret,  having  a  diameter  about  one-sixth  as  great  as  that  of 
the  base  of  the  tail.  The  length  of  the  tail  is  about  two  and  one-half  times  as 
great  as  that  of  the  anal  body-diameter.  This  description  is  derived  from  a 
specimen  in  which  the  sexual  organs  are  represented  by  an  oval  body  consisting 
mainly  of  two  cells.  Supplements  twenty-one,  slightly  elevated,  flat,  similar 
to  those  frequently  seen  on  the  males  of  Chromadora.  These  organs  occupy  a 


294  ORDER  SYNONCHIA,  ORDER  MESONCHIA 

distance  about  three  times  as  great  as  the  length  of  the  tail;  the  posterior  ones 
are  a  little  nearer  together  than  the  anterior  ones.  The  two  hindermost  are 
opposite  the  anterior  halves  of  the  spicula,  while  the  antepenultimate  is  a  little  in 
front  of  the  proximal  ends  of  the  spicula.  The  average  distance  between  the 
organs  is  one  and  one-half  to  two  times  as  great  as  their  diameter.  No  special 
setae  or  papillae  have  been  seen  on  the  tail  either  in  front  of  the  anus  or  behind 
it.  The  strongly  developed  spicula  taper  at  both  ends.  The  proximal  ends  are 
slightly  hooked  toward  the  ventral  side  of  the  body,  and  also  slightly  enlarged, 
so  that  they  are  distinctly  cephalated.  The  main  portion  of  the  framework  of 
each  spiculum  consists  of  four  refractive  elements  arranged  in  two  pairs,  —  one 
dorsal,  the  other  ventral.  The  slightly  curved  accessory  piece  leaves  the  surface 
of  the  spicula  somewhat  and  then  recurves  so  as  to  touch  them  again.  The  ejacu- 
latory  duct  is  half  as  wide  as  the  body. 

Habitat:  Mud,  tide  pool,  low  tide,  Portsmouth,  N.  H.,  U.  S.  A.  At  first  sight 
this  species  appears  to  be  a  Cyatholaimus  but  examination  shows  a  number  of 
important  differences.  The  pharynx  is  not  striated  in  the  same  way  as  that  of 
Cyatholaimus,  nor  is  there  a  dorsal  onchium.  The  examination  has  not  revealed 
the  pores  frequently  to  be  seen  along  the  borders  of  the  lateral  fields  in  Cyatho- 
laimus. Most  Cyatholaimi  have  a  single  testis.  This  genus  also  bears  a  con- 
siderable resemblance  to  Halichoanolaimus,  but  differs  in  that  the  numerous, 
minute  pharyngeal  denticles  of  Halichoanolaimus  are  lacking.  Alternating  with 
each  pair  of  the  twelve  amalgamated  lips  there  are  papillae  which  extend  an 
exceedingly  short  distance  beyond  the  margin  of  the  lips.  Fig.  75,  p.  293. 

IX.     Order  Mesonchia. 

76.  Mesonchium  poriferum  n.  sp.  The  thickish,  colorless  cuticle  has  on  the 
females  three  rows  of  round  cuticular  elements  on  the  lateral  fields,  on  the  males, 
two;  similar  markings  arranged  irregularly  occur  on  the  ventral  surface.  Setae, 
half  as  long  as  the  corresponding  part  of  the  body  is  wide,  are  found  scattered  on 
the  neck.  None  are  seen  on  the  body.  Rows  of  pores  occur  on  the  lateral  fields, 
one  row  on  each  side  just  outside  the  longitudinal  rows  of  lateral  markings.  The 
diameter  of  these  pores  is  about  equal  to  the  width  of  two  annules;  the  distances 

%tcph(4)\w(3)   pplOl  (6+6)     *     *^^J2*t!Ljfe_,M     separating  them  longi- 
^  --.\A__J>-         j        L2      2"       2-7         «-s       2.i/2-4"  tudmally   are    about 

equal  to  the  diameter 
'5"  of  the  pores.  Lips 
confluent,  rounded,  thick.  Each  onchium 
appears  to  be  the  apex  of  a  plate  which 
forms  one  of  the  three  faces  of  the  pharyn- 
geal  cavity.  These  plates  are  thickened  at 
the  anterior  end  of  the  pharynx.  Pharynx 


ward  in  a  direction  parallel  to  the  axis  of  the  head.  Neck  conoid.  Oesophagus 
conoid,  with  a  faint  cardiac  swelling,  hardly  to  be  called  a  bulb.  Near  the 
nerve-ring,  the  oesophagus  is  one-half,  and  finally  three-fifths,  as  wide  as  the 
corresponding  portion  of  the  neck.  The  lining  of  the  oesophagus  finds  optical 
expression  in  three  parallel,  refractive  lines.  Its  musculature  is  rather  coarse. 
There  is  a  more  or  less  hemispherical  cardia,  one-fourth  as  wide  as  the  base  of 
the  neck.  The  intestine  becomes  at  once  three-fourths  as  wide  as  the  body,  its 


MESONCHIUM,    PEPSONEMA  295 

cells  containing  numerous  granules  of  rather  uniform  size,  and  of  about  the  same 
diameter  as  the  dot-like  lateral,  cuticular  elements.  The  conoid  tail  tapers  from 
in  front  of  the  anus  and  becomes  cylindroid  in  the  posterior  third,  where  it  is 
one-seventh  as  wide  as  at  the  base.  The  elongated  caudal  glands,  which  empty 
by  separate  ducts,  are  packed  in  the  anterior  half  of  the  tail.  Slender,  rather 
tapering  setae,  to  the  number  of  twelve  occur  on  each  ventrally  submedian  line 
in  front  of  the  anus;  about  seven  setae  occur  on  each  of  the  submedian  lines  on 
the  tail.  The  pre-anal  setae  are  scattered  through  a  distance  about  equal  to  the 
length  of  the  tail,  and  are  mostly  very  inconspicuous,  especially  anteriorly.  The 
lateral  fields  are  two-sevenths  as  wide  as  the  body.  The  non-granular,  ellipsoidal 
renette  cell  occurs  near  the  cardia,  and  is  one-third  as  wide  as  the  base  of  the  neck. 
The  large,  rather  conspicuous,  elevated  vulva  leads  into  a  large,  conoid,  muscu- 
lar, more  or  less  cutinized  vagina,  which  extends  inward  half  way  across  the  body. 
It  is  probable  that  the  prolate  eggs  are  about  as  long  as  the  body  is  wide,  but  there 
is  some  uncertainty  about  this.  An  unusual  feature  is  that  the  ovaries  are 
reflexed  only  near  their  blind  ends.  Each  contains  about  twenty  ova,  arranged 
more  or  less  single  file.  The  tail  of  the  male  is  cylindroid  in  the  posterior  two- 
fifths,  where,  at  its  widest,  it  is  only  one-tenth  as  wide  as  at  the  anus.  The  rather 
long,  slender,  uniform,  more  or  less  acute,  colorless  spicula  are  straight  to  near 
the  middle,  but  are  arcuate  distally.  Their  proximal  ends  appear  to  lie  more  or 
less  ventrad  from  the  body-axis.  The  rather  strong,  slender  accessory  piece  has 
an  applied  part  one-fourth  to  one-third  as  long  as  the  spicula;  its  uniform,  more 
or  less  blunt,  rather  slender  apophysis  bends  and  extends  backward  parallel  to 
the  body-axis.  The  proximal  extremity  of  the  apophysis  lies  dorsad  from  the 
body-axis.  To  be  seen  along  the  posterior  half  of  the  region  occupied  by  the 
oblique  copulatory  muscles,  is  a  pre-anal  series  of  almost  invisible  ventral  inner- 
vations,  the  distances  between  which  are  about  equal  to  one-third  the  body-diam- 
eter. The  space  occupied  by  the  oblique  copulatory  muscles  is  about  two  and 
one-half  times  as  long  as  the  tail. 

Habitat:  Marine  algae,  Key  West,  Fla.,  U.  S.  A.     Flemming  to  glycerine  jelly. 
Fig.  76,  p.  294. 

77.  Pepsonema  pellucidum  n.  sp.  Cuticle  of  medium  thickness.  Anteriorly 
the  number  of  the  longitudinal  rows  of  "beads"  appears  fewer  than  near  the  tail, 
where  there  are  sometimes  six 
or  possibly  eight  rows.  Forma- 
tion of  the  cuticula  like  that 
found  in  the  genus  Spilophora. 
Somatic  setae  very  minute.  ,„  , 
Lips  six,  or  three  and  two- 
parted.  Mouth-opening  about 
one-fourth  as  wide  as  the  front 
of  the  head,  and  leading  into  a 
minute  vestibule,  which  is  X  750 
nearly  twice  as  wide  as  the  mouth  opening  and  very  shallow.  The  pointed, 
cutinized  apices  of  three  inner  lips  come  together  in  this  vestibule;  they  are  of 
nearly  equal  size,  the  dorsal  being  only  slightly  larger  than  the  two  submedian 
ones.  It  may  possibly  be  questionable  whether  this  genus  should  not  be  placed 
in  the  Anaxonchia.  At  the  base  of  the  pharynx,  there  are  one  or  two  minute, 
onchium-like  processes,  which  are  so  small  as  to  be  easily  overlooked.  The 
oesophagus  continues  to  have  the  same  width,  or  to  decrease  slightly,  until  it 


296  ORDER   MESONCHIA 

passes  through  the  nerve-ring.     Thence  onward  it  increases  rather  regularly, 
though  finally  there  is  a  tendency  to  form  a  much  elongated  bulb  two-thirds  to 
three-fourths  as  wide  as  the  base  of  the  neck.     There  is  a  distinct  though  small 
cardia.     The  intestine  begins  as  a  tube  one-half  to  one-third  as  wide  as  the  body, 
but  soon  expands  so  as  to  become  two-thirds  as  wide  as  the  body.     It  presents 
i.s      5.4 T- 12-       "-*?~V     ?2-.  >2.?-.  the  very  interesting  peculiarity  of  containing  in 
'ij      2.5^  3-  its  anterior  part  about  a  score  of  cells  whose 

1.4      6.7  T*-H.        .-*-.     ?!-.  ?2.  ..  staining  properties  indicate  that  a  different  phys- 
ij      z.y  2-8         3-7  *»«.•  iological  function  is  discharged  in  this  portion  of 

the  intestine,  possibly  some  gastric  function.  This  is  in  line  with  other  anatomi- 
cal observations,  indicating  that  the  anterior  portion  of  the  nema  intestine 
possesses  functions  differing  from  those  of  the  middle  and  posterior  portions. 
Opposite  the  cardiac  constriction,  there  are  two  or  three  bodies  closely  resembling 
those  usually  seen  in  this  position  in  the  genus  Trilobus.  The  nature  of  these 
organs  still  remains  problematical.  From  the  slightly  depressed  anus,  the  rec- 
tum, which  is  somewhat  shorter  than  the  anal  body-diameter,  extends  inward 
almost  at  right  angles  to  the  ventral  surface.  Owing  to  the  strong  development 
of  the  somatic  muscles,  the  intestine  is  only  about  one-half  as  wide  as  the  body. 
The  tissues  of  the  oesophagus  evidently  contain  glands,  of  which  the  dorsal  is 
much  the  more  highly  developed;  from  its  structure,  it  would  be  easy  to  suppose 
that  the  gland  in  the  dorsal  sector  empties  at  the  pharynx,  but  no  conclusive 
proof  of  this  has  been  obtained.  In  a  similar  way,  it  may  be  surmised  that  the 
glands  in  the  submedian  sectors  empty  into  the  lumen  of  the  oesophagus  in  the 
vicinity  of  the  nerve-ring.  The  tail  is  at  first  convex-conoid  in  such  fashion  that 
at  the  middle  it  is  only  about  one-sixth  as  wide  as  at  the  anus;  from  the  middle 
onward  it  is  cylindroid,  expanding  slightly  to  form  the  rather  rounded  spinneret. 
The  ovaries  may  be  reflexed  for  a  short  distance  near  their  blind  ends.  The  tail 
of  the  male  is  rather  strongly  ventrally  arcuate.  For  a  distance  in  front  of  the 
anus  equal  to  about  five-body-diameters,  there  is  found  a  ventral  row  of  sub- 
equidistant  innervations  probably  amounting,  in  fact,  to  a  series  of  supple- 
ments. These  begin  near  the  anus,  where  they  are  only  one-third  as  far  apart 
as  at  the  front  end  of  the  series.  These  very  inconspicuous  organs  are  nearly 
co-extensive  with  the  series  of  oblique  copulatory  muscles.  There  are  two  lat- 
eral and  two  ventrally  submedian  rows  of  setae  on  the  tail,  the  lateral  rows 
lying  close  to  the  outside  lateral  rows  of  beads.  Of  these  lateral  pairs  there 
are  eight  or  nine.  Each  of  the  two  sub-ventral  rows  has  about  twelve  to  fourteen 
setae.  There  are  a  few  other  setae  scattered  irregularly  on  the  ventral  side  of 
the  tail,  as  well  as  in  the  dorsally  submedian  positions.  Spicula  much  elongated, 
narrow,  acute;  guided  by  accessory  pieces  about  as  long  as  the  anal  body-diam- 
eter, which  have,  projecting  backward  from  their  middle  parts,  processes  nearly 
as  long  as  they  themselves  are.  The  distal  ends  of  the  spicula  are  obscurely 
retrorsely  barbed.  The  caudal  glands  seem  to  be  located  in  the  tail.  It  appears 
that  sometimes  the  distal  extremity  of  the  anterior  testis  may  be  reflexed  for  a 
short  distance.  The  posterior  testis  is  considerably  smaller  than  the  anterior. 
Habitat:  Mud  in  the  shallow  portions  of  the  harbor  of  Kingston,  Jamaica.  The 
name  Pepsonema  is  suggested  by  the  interesting  cells  found  in  the  anterior 
portion  of  the  intestinal  wall.  Such  specially  differentiated  cells  are  now  known 
for  all  parts  of  the  nema  intestine.  In  general  the  specialized  cells  of  the  pos- 
terior part  of  the  intestine  are  histologically  different  from  the  specialized  cells 
of  the  anterior  portion.  Fig.  77,  p.  295. 


TRISSONCHULUS 


297 


m(3J.....lb(6) 


X.  Order  Aponchia. 

78.  Trissonchulus  oceanus  n.  sp.  Cuticle  naked,  practically  without  marks  of 
any  kind.  Onchia  refractive,  in  contour  roughly  equilateral,  slightly  curved, 
apparently  with  an  outward  stroke.  When  the  mouth  is  slightly  open,  the  apices 
of  the  teeth  are  on  a  level  with  the  surface  of  the  head.  Neck  slightly  conoid, 
—convex-conoid  at  the  head.  Amphids  very  faint.  Inner  surface  of  each  of  the 
six  lips  armed  with  scores  of  exceedingly  minute,  closely  set  denticles.  Oesoph- 
agus cylindroid,  then  conoid  in  the  posterior  fourth,  where  there  is  a  faint  cardiac 
swelling,  which  can  hardly  be  called  a  bulb.  At  the  nerve-ring  the  oesophagus  is 
one-half,  and  finally  three-fifths,  as  wide  as  the  corresponding  part  of  the  neck. 
The  indistinct  lining  is  expressed  by  three  parallel 
lines  occupying  a  space  two-sevenths  as  wide  as 
the  oesophagus.  There  is  a  conoid  cardia  one-half 
as  wide  as  the  base  of  the  neck.  The  thin-walled 
intestine  becomes  at  once  three-fourths  as  wide  as 
the  body,  at  least  when  gorged.  Its  cross-section 
is  probably  made  up  of  eight  to  ten  cells.  These 
cells  contain  scattered  colorless  granules  of  vari- 
able size,  the  largest  of  which  are  one-fortieth  as 
wide  as  the  body.  Tail  sub-cylindroid  in  the  ante- 
rior three-fourths.  The  spinneret  presents  the 
peculiarity  of  being  on  the  ventral  surface  of  the 
tail  some  distance  from  the  tip.  (See  illustra- 
tion.) The  elongated-ellipsoidal  caudal  glands, 
as  long  as  the  body  is  wide  and  one-third  as  wide 
as  long,  are  located  in  front  of  the  copulatory  mus- 
cles. They  form  a  loose  tandem,  and  empty 
through  distinct  ducts  and  ampullae,  the  latter 
being  large  and  filling  the  tail.  There  are  no  cau- 
dal setae.  The  lateral  fields  are  one-third  as  wide 
as  the  body  and  contain  large,  ellipsoidal  cells 
nearly  as  wide  as  the  fields  themselves,  occurring 
at  intervals  of  one  to  three  body-widths;  these  are 
apparently  glandular,  and  connect  with  the  sur- 
face by  means  of  pores  on  the  lateral  line.  The 
excretory  pore  is  at  the  lips  and  is  directed  for- 
ward. The  renette  cell,  one  neck-length  behind 
the  cardia,  and  as  long  as  the  neck,  is  granular  and 

contains  a  large  nucleus;  its  duct  is  about  as  wide     ±\ *1 — H '"'fe  -^'*  >  3.6 

as  the  cuticle  is  thick,  and  being  coarsely  granular, 

is  rather  easily  followed.  There  is  an  anterior  rudimentary  part  to  the  female 
sexual  organs  two  to  three  body-widths  long.  From  the  continuous  vulva,  the 
medium-sized,  more  or  less  tubular  vagina  leads  inward  two-fifths  the  distance 
across  the  body.  The  broad,  cylindroid  ovary  contains  about  thirty  ova, 
arranged  single  file  proximally,  but  irregularly  distally.  Tail  of  the  male  smaller 
and  more  arcuate  than  that  of  the  female,  and  more  nearly  conoid.  The  proximal 
ends  of  the  stoutish,  tapering,  rather  blunt  spicula  appear  to  lie  opposite  the 
body-axis.  There  is  a  rather  frail,  slender  accessory  piece.  There  is  a  low  and 
more  or  less  obscure  ventral  pre-anal  elevation  at  the  anterior  portion  of  the 
region  occupied  by  the  copulatory  muscles.  This  may  perhaps  partake  of  the 
nature  of  a  supplementary  organ.  On  each  side,  in  front  of  the  anus,  there  are 


X750 


298  ORDER   APONCHIA 

three,  and  behind  the  anus  four,  ventrally  submedian  papillae,  the  former  sepa- 
rated by  spaces  about  one  and  one-half  times  as  great  as  the  width  of  the  body. 
Of  those  on  the  tail  two  are  in  front  of  the  spinneret  pore  and  two  behind.  Of  the 
two  testes  the  anterior  one  is  much  the  longer;  both  are  narrow.  The  ejaculatory 
duct  is  one-half  as  wide  as  the  body,  the  vas  deferens  one-fifth  to  one-third. 
The  copulatory  muscles  occupy  a  space  five  times  as  long  as  the  tail.  The  sperma- 
tozoa are  more  or  less  ellipsoidal,  and  one-fifteenth  to  one-tenth  as  wide  as  the 
body  of  the  female.  In  the  male,  at  a  distance  in  front  of  the  anus  four  to  eight 
times  the  length  of  the  tail  there  are  seven  clavate,  long  glands  connecting  back- 
ward with  the  ejaculatory  duct.  These  glands  darken  in  Flemming's  solution.  In 
front  of  these  glands,  for  a  distance  equal  to  four  to  five  times  the  body-diameter, 
there  are  about  seventeen  spherical  glands  not  darkening  in  Flemming.  These 
also  seem  to  connect  with  the  ejaculatory  duct. 

Habitat:  Seaweed  that  drifted  ashore  after  a  storm  at  Ocean  Beach,  Miami, 
Florida,  U.  S.  A.  Also  found  in  beach  sand  at  Ocean  Beach.  Flemming  to 
glycerine  jelly.  Fig.  78,  p.  297. 

79.  Aponchium  cylindricolle  n.  sp.  When  the  lips  are  closed  the  three  onchia 
almost  completely  fill  the  pharyngeal  cavity.  Extending  backward  and  slightly 

outward  from  the  bases  of  the  teeth  are  refractive 
— i?^ — ^L_ — 2L_>1.9_.  markings  in  the  pharynx,  indicating  folds, — 

evidence  that  the  cavity  containing  the  teeth  can 
1.8  6.  10.  "''M  93.5  >  1 9 ..  be  everted.  The  pharyngeal  cavity  seems  tc 

merge  gradually  into  the  lumen  of  the  oesoph- 
agus; it  probably  extends  backward  a  distance  equal  to  the  diameter  of  the  head. 
Onchia  of  very  slightly  unequal  size; — the  dorsal  perhaps  smallest,  the  submed- 
ian ones  equal.  The  oesophagus  continues  to  have  the  same  diameter  until  after 
it  passes  through  the  nerve-ring,  when  it  expands  to  form  the  elongated,  pyri- 
form,  posterior  bulb  or  swelling,  three-fourths  as  wide  as  the  base  of  the  neck. 
There  is  a  distinct,  somewhat  cylindroid  cardia,  about  one-third  as  long  as  the 
neck  is  wide.  The  thick-walled  intestine,  which  is  separated  from  the  oesophagus 
by  a  broad  and  deep  constriction,  soon  becomes  three-fourths  as  wide  as  the  body. 
Its  cross-section  would  display  six  to  eight  cells.  The  cells  of  the  anterior  por- 
tion of  the  intestine  for  a  distance  twice  as  great  as  the  corresponding  body- 
diameter  appear  to  be  of  a  slightly  different  character  from  those  farther  back, 
as  they  almost  invariably  stain  somewhat  differently.  The  preliminary  cells  of 
the  intestine,  namely,  a  transverse  series  of  about  six  cells,  are  undoubtedly  of 
a  larger  size  than  those  immediately  following,  and  stain  in  a  different  manner; 
they  fail  to  take  acid  carmine  stain,  when  the  cells  immediately  following  stain 
well.  These  cells  are  packed  with  granules  of  rather  uniform  size.  The  succeed- 
ing intestinal  cells  contain  numerous  yellowish  granules  of  variable  size,  which 
are  rather  irregularly  disposed.  A  notable  feature  of  the  intestine  is  the  lining, 
which  is  unusually  thick,  and  consists  of  two  elements;  an  interior  thin,  refrac- 
tive membrane  surrounded  by  a  non-staining  layer  nearly  as  thick  as  that  portion 
of  the  intestine  containing  the  granules,  already  mentioned.  In  many  parts  of 
the  intestine  this  lining,  composed  of  the  two  above-mentioned  elements,  occu- 
pies fully  half  the  optical  longitudinal  section.  Anus  raised,  rectum  somewhat 
shorter  than  the  anal  body-diameter.  The  tail  begins  to  taper  slowly  from  some 
little  distance  in  front  of  the  anus.  Behind  the  anus  it  tapers  somewhat  more 
rapidly,  and  is  conoid  to  the  terminus.  The  three  saccate  caudal  glands  form  a 
close  tandem  series  in  the  anterior  half  of  the  tail.  The  nuclei  of  these  cells 


APONCHIUM 


299 


are  slung  in  a  rather  fine  net-work  of  protoplasm.  The  lateral  fields  are  fully 
one-third  as  wide  as  the  body.  The  renette  cell  is  not  yet  fully  understood. 
There  is  a  series  of  rather  prominent  cells  a  short  distance  behind  the  base  of  the 
neck  on  the  ventral  side  of  the  intestine  which  undoubtedly  constitutes  the 


X750 


renette.  In  one  typical  specimen  these  cells  were  arranged  as  follows:  First, 
an  elongated-ellipsoidal  cell,  which  failed  to  take  the  carmine  stain,  but  con- 
tained a  distinctly  stained  nucleolus  in  its  nucleus.  This,  was  followed  by  a  cell 
which  stained  rather  strongly,  which  in  turn  was  followed  by  a  pair  of  cells  which 
did  not  stain,  except  in  their  nuclei;  these  two  cells  were  arranged  side  by  side, 
and  were  the  largest  of  the  series,  being  nearly  half  as  wide  as  the  body,  and 
nearly  twice  as  long  as  wide.  Behind  this  pair  of  cells  there  was  a  single  cell 


300 


ORDER  APONCHIA,  ORDER  TRIPLONCH1A 


resembling  the  first  member  of  the  series,  and  behind  this  one  or  two  others 
arranged  tandem.  This  entire  series  occupies  a  distance  equal  to  the  length  of 
the  neck.  From  the  raised  vulva  the  vagina  extends  inward  and  forward.  The 
outstretched  ovary  contains  fifty  or  more  developing  ova  arranged  in  double 
file,  except  near  the  blind  end,  which  is  located  near  the  middle  of  the  body. 
The  eggs  are  of  large  size,  elongated,  about  one  and  one-half  times  as  long  as  the 
body  is  wide  and  about  two-fifths  as  wide  as  long.  In  all  those  thus  far  seen  the 
spherical  nucleus  is  of  unusually  large  size.  There  is  no  posterior  rudimentary 
branch  to  the  sexual  organs.  Well-developed  accessory  pieces  surround  the  dis- 
tal ends  of  the  spicula.  With  them  a  median  piece  extends  along  the  spicula 
and  appears  to  end  opposite  the  body-axis,  near  the  base  of  the  apophysis.  The 
karyokinesis  of  the  sperm atocytes  shows  the  arrangement  of  the  chromosomes 
in  spireme  threads,  something  very  uncommon  in  nemas. 
Habitat:  Larat,  East  Indies.  Marine  Fig.  79,  p.  299. 


XI.  Order  Triplonchia. 

80.  Triplonchium  cylindricum  n.  sp.  Cuticle  naked  as  in  the  case  of  nearly 

6.9  13.      "'541"      98.              a^   Triplonchs. 

„,  3.i  37a         §T§ IT  1-2"  Cylindroid  neck 

7.6  15.        "-M         97.              ending  in  a  con- 

*«ni'in"nm  '"X   ^    HUB    'Bfliu       /m-  3'4    4~       4'2  ~°'7   '  "  vex-conoid  head- 

*jy  \\  Amphids  more  or  less  protrusile,  projecting  con- 
mnd  siderably  in  all  specimens  killed  with  Flemming's 
solution.  (See  illustration.)  In  some  respects 
the  amphids  are  reminiscent  of  those  of  certain 
Mermithidae.  Oesophagus  mainly  cylindroid, 
but  finally  expanding  to  form  a  pyriform  bulb 
nearly  two-thirds  as  wide  as  the  base  of  the  neck, 
and  having  a  rather  indistinct  valve  one-sixth  as 
wide  as  itself.  The  lining  of  the  oesophagus  is 
lot  a  very  distinct  feature.  There  is  no  very 
distinct  cardia.  The  intestine  becomes  at  once 
about  two-thirds  as  wide  as  the  body.  The  cells 
contain  numerous  refractive  spherical  granules,  the  largest  of  which  are  about 
one-sixth  as  wide  as  the  body,  the  smallest  of  which  are  very  much  smaller. 
These  granules  are  packed  so  closely  together  as  to  obscure  the  details  of  the 
histological  structure  of  the  intestine.  Anus  continuous;  rectum  slightly  refrac- 
tive. The  lateral  fields  have  not  been  clearly  seen,  but  appear  to  be  about  one- 
fourth  as  wide  as  the  body.  Renette  unknown.  The  nerve-ring  surrounds  the 
oesophagus  squarely,  and  there  are  numerous  nerve  cells  close  together,  both  in 
front  of  the  nerve-ring  and  behind  it,  filling  the  greater  part  of  the  cavity  of  the 
neck.  From  the  slightly  raised  vulva  the  distinctly  cutinized  vagina  leads  back- 
ward a  distance  nearly  equal  to  half  the  corresponding  body  diameter;  it  then 
joins  the  single  uterus,  which  extends  first  backward,  then  forward.  This  latter, 
when  empty,  appears  to  be  about  two-fifths  as  wide  as  the  body.  The  end  of 
the  posterior  ovary  lies  about  one  to  two  body-widths  behind  the  vulva.  Noth- 
ing is  known  concerning  the  size  and  form  of  the  eggs.  There  is  a  cell  located 
about  as  far  behind  the  base  of  the  neck  as  this  latter  is  behind  the  anterior 
extremity,  which  attracts  attention  on  account  of  its  somewhat  peculiar  appear- 
ance. It  presses  the  intestine  to  one  side,  and  has  a  distinct  nucleus,  with  a 


TRIPLONCHIUM,    APHELENCHULTJS 


301 


refractive  nucleolus.  Possibly  this  cell  is  the  renette  cell.  The  tail  of  the  male 
is  a  little  more  strongly  developed  than  that  of  his  mate.  No  pre-anal  supple- 
ments, though  there  appear  to  be  one  or  two  obscure  papillae  just  in  front  of  the 
anus.  There  are  very  obscure,  straight  accessory  pieces;  these  may  be  little 
more  than  thickenings  of  the  wall  of  the  cloaca.  The  ejaculatory  duct  is  two- 
fifths,  the  vas  deferens  about  two-thirds,  as  wide  as  the  body.  In  glycerine  speci- 
mens the  spermatocytes  are  distinctly  refractive,  ellipsoidal  bodies,  about  one- 
sixth  as  long  as  the  body  is  wide.  The  dorso-ventral  view  of  the  amphids  is  very 
instructive.  As  seen  in  glycerine  preparations  fixed  with  Flemming's  solution, 
the  external  amphids  appear  as  tubular  protrusile  organs,  arcuate  in  form,  and 
three  to  four  times  as  long  as  wide.  They  may  be  protruded  for  at  least  half 
their  length.  Their  outer  surface  is  of  a  refractive  character,  and  there  appears 
to  be  a  slightly  refractive  core.  At  the  extremity  they  are  almost  imperceptibly 
expanded,  somewhat  hemispherical  in  form,  with  the  terminal  surface  much 
thinner  and  less  refractive  than  the  lateral.  They  appear  to  slide  in  an  inner  tube 
located  in  the  head,  which  is  also  cutinized.  This  tube  extends  inward  and  back- 
ward, and  ends  opposite  the  base  of  the  pharynx,  and  is  therefore  arcuate  like 
the  amphid  itself.  Tubes  leading  back  from  the  external  amphid  may  be  traced 
at  least  half  way  to  the  nerve-ring.  The  inner  elements  of  the  tube  are  refrac- 
tive, and  are  seen  to  lie  more  or  less  parallel  to  the  body-axis,  but  as  yet  have  not 
been  connected  up  with  any  internal  cellular  structure.  There  are  comparatively 
few  ova  in  the  ovary,  perhaps  about  a  dozen  in  all,  arranged  somewhat  irregularly. 
Habitat:  Humus,  Plummer's  Island,  Potomac  River,  near  the  District  of  Colum- 
bia, U.  S.  A.  Fig.  80,  p.  300. 


81.  Aphelenchulus  mollis  n.  sp.     Cuticle  thin,  naked;  the  wings,  extending  from 
the  neck  to  near  the  terminus  and  bearing  about  twelve,        j- 
very  fine,  longitudinal  striae,  are  hardly  raised  at  all.     Con- 
tour, very  minutely  crenate.     The  head,  which  is  more  or 
less  rounded  in  the  adult,  is  sub-truncate  in  the  young,  and  tib  (HI- 
the  region  is  sometimes  set  off  by  an  almost  imperceptible 
broad,  shallow  constriction.     The  spear  is  nearly  vestigial, 
probably  nearly  functionless,  and  may  act  merely  as  a  tube 
through  which  the  food  passes.     It  is  not  clear  what  the 
motive  force  in  deglutition  is,   as  the  usual  oesophageal 
bulbous  pump  is  absent.     Oesophagus  cylindroid  or  faintly 
cephaloboid.     In  the  larvae  opposite  the  excretory  pore  are  '/'*• 
to  be  seen  two  successive  breaks  in  the  lining  of  the  oesoph- 
agus, which  are  probably  vestiges  of  a  bulb.     At  first,  the 
oesophagus  is  two-fifths,  near  the  nerve- ring  one-half,  and 
finally  one-fourth,  as  wide  as  the  corresponding  portion  of 
the  neck;  the  lining  is  subdistinct,  the  musculature  fine  and 
colorless.     There  is  no  car-     1.1      8.9  _u.  Y        93.2   x    ^ 

dia.          The       oesophagus      '9  / 1-8      2-1 
changes  gradually  into  the 
intestine,    as    in    Aphelen- 
chus.     In    the    larvae,    the 


.1    /    1.8—  2.  2. 2 

Upper  Fig— Adult  male. 


ina 


Lower  Figs.— Adult  female. 


thick-walled  intestine  gradually  becomes  three-fifths  as  wide  as  the  body. 
Its  lining  is  refractive  and  in  cross-section,  it  presents  one  to  two  cells  only, 
which  alternate  with  each  other  as  in  some  Rhabdites.  The  anus  is  con- 


302 


ORDER   TRIPLONCHIA 


arm 


tinuous,  the  rectum  inconspicuous  and  about  as  long  as  the  anal  body  diameter. 
The  nuclei  of  the  intestinal  cells  are  clear,  and  have  twice  the  diameter  of  the 
largest  intestinal  granules,  and  present  a  nucleolus.  The  cells  of  the  intestine 
are  usually  packed  with  granules  of  variable  size,  the  largest  of  which  are  one- 
ninth  as  wide  as  the  body  and  are  so  arranged  as  to  give  rise  to  a  more  or  less 
distinct  tessellated  effect.  Tail  of  the  adult,  as  shown  in  the  illustration.  The 
tail  of  a  larva  is  more  or  less  cylindroid,  but  slightly  conoid  and  at  the  end  bluntly 
rounded  and  almost  imperceptibly  apiculate.  There  are  no  caudal  glands. 
i  ^°PP°site  the  base  of  the  oesophagus, 
.....  there  are  two  to  three  nuclei  similar  to 
those  often  found  in  the  genera  Tylen- 
.CUt  chus  and  Aphelenchus,  and  probably  hav- 
ing the  same  function,  namely,  that  of 
salivary  glands.  The  long  renette,  which 
LSImUt  appears  to  be  sometimes  on  the  right, 
sometimes  on  the  left,  extends  back  along 
the  lateral  field  a  long  distance;  it  has 
been  followed  for  three-fourths  the  length 
of  the  body.  The  nerve-ring  is  accom- 
dl  panied  by  rather  obscure  nerve  cells. 
Only  the  blind  end  of  the  tapering  ovary 
^  „-  is  reflexed.  The  vulva  is  large  and  con- 
spicuous, and  is  somewhat  elevated,  espe- 
cially in  front.  The  straight  uterus  contains  ellipsoidal  to  elongated  eggs,  which 
are  about  as  long  as  the  body  is  wide,  measuring  forty  by  twenty-five  microns. 
They  begin  segmenting  before  deposition. 

Habitat:  Found  at  Falls  Church.  Va.,  U.  S.  A.,  parasitic  in  a  wood-boring 
beetle,  determined  by  Mr.  F.  C.  Craighead  as  Cyllene  picta  Drury.  Sixteen 
thousand  larvae  and  a  few  adult  females  were  found  in  one  beetle.  Both  male 
and  female  beetle  are  infested,  usually  with  only  a  few  female  parasites  ;—  at  least 
such  is  the  condition  in  the  month  of  May.  Of  fourteen  female  insects,  three 
were  infested;  of  twelve  males,  seven  were  infested.  As  a  rule,  only  a  few  adult 
females  of  Aphelenchulus  mollis  occur  in  one  host,  about  one  to  eight.  Two 
living  adult  males  of  Aphelenchulus  mollis  were  found  in  the  castings  of  beetles 
taken  from  infested  logs.  These  are  the  only  adult  males  so  far  seen.  This 
finding  may  indicate  that  the  females  are  fertilized  before  entering  the  host. 
The  parasites  are  found  in  the  thorax  of  the  beetle,  as  well  as  the  abdomen.  Fig. 
81a,  p.  301;  Fig.  816. 

.4         .»»        14.  -88.  92. 


gmm 


82.  lotonchium  imperfectum  (Butschli)  nom.  nov.  t-6'*  'A,  '!'«  2-5 
Striae  fine;  contour  entire.  Head  abruptly  truncate,  set  off  by  expansion.  Spear 
exceedingly  minute,  eight  microns  long,  about  one-fourth  to  one-fifth  as  long  as 
the  head  is  wide,  simple,  plain,  apparently  not  bulbed;  in  the  male,  the  spear  is 
difficult  to  see,  being  reduced  to  a  mere  point.  Neck  conoid;  amphids?.  Intes- 
tine very  transparent;  anus  indistinct.  Tail  of  the  female  conical  from  the  vulva, 
acute.  Excretory  duct  single,  much  coiled.  Ovary  outstretched  forward;  eggs 
somewhat  longer  than  body  is  wide,  half  as  wide  as  long,  deposited  after  segmen- 
tation. Spicula  L-form,  tapering,  cephalated  by  constriction,  considerably 
longer  than  the  anal  body-diameter;  accessory  pieces  none;  bursa  well-developed, 
springing  from  considerably  in  front  of  the  spicula  and  extending  somewhat 
beyond  the  terminus. 

Habitat:  In  rotting  fungi,  Germany.     Syn.  Tylenchus  imperfeclus  Btsli. 


ONCHIUM,    DORYLLTUM 


303 


XII. 


83.  Onchium  ocellatum   n.   sp. 


Order  Axonchia 

.27       7.2        19.         Y?52t 


1.8  1.2'  "  "  Cuticle  thin,  the 
transverse  striae  almost  impossible  of  resolution.  Except  for  the  cephalic  setae, 
the  cuticle  is  naked.  Spear  hollow,  brownish,  very  thin-walled.  Though  the 
yellowish,  solid,  refractive  eye-spots  are  sublateral  in  position,  they  are  rather 
near  together.  The  specimens  thus  far  examined  do  not  enable  one  to  make  a 
clear  distinction  between  the  oesophagus  and  the  intestine.  Connected  with 
the  posterior  part  of  the  oesoph-  set  (ph  (4-l\^  QMph  ^&_ 
agus  are  large  glandular  cells,  (^^C\  //  A 

probably  three  in  number,  judg-  "\vv^H% 

ing  by  the  number  of  nuclei.    These  w  aHHm  \VW      m 

structures  seem  to  be  homologous 
with  those  found  in  a  similar  posi-  ^ 
tion  in  Tylenchus  and  Aphelen- 
chus,  but  their  actual  connection 
with  the  lumen  of  the  oesophagus  *  750 

is  problematical,  as  no  connecting  duct  has  been  seen.     The   fl(X 
best  interpretation  seems  to  be  to  consider  these  structures 
as  a  part  of  the  oesophagus,  but  it  is  entirely  possible  that   ^  p 
the  oesophagus  ends  just  in  front  of  these  glands.     The  thick- 
walled  intestine,  which  has  a  very  distinct,  refractive  zig-    „,, 
zag  lumen,  becomes  almost  at  once  three-fourths  as  wide  as 
the  body.     From  the  elevated  anus,  the  prominent,  cutinized      ,      /a 
rectum  extends  inward  a  distance  equal  to  the  anal  body-   •> 
diameter.     The  cells  of  the  intestine  contain  numerous  some- 
what variable  yellowish  granules,  the  largest  of  which  are   OCt  /W. 
one-sixteenth  as  wide  as  the  body.    The  conoid  tail  is  arcuate. 

Caudal  glands  have  not  been  clearly  deciphered,  but  they    ff/ 

probably  lie  behind  the  anus  in  the  anterior  half  of  the  tail 

in  a  loose  tandem.     They  are  narrow  and  elongated.     The   (fa[  rffl 

elongated,  granular  renette  cell,  twice  as  long  as  the  body 

is  wide,   and  about  one-third  as  wide  as  long,   is  located       //  ,./ 

six   to   eight   body-widths   behind   the   neck.     The   single, 

reflexed  sexual  organ  extends  forward;  the  accompanying 

formula,  correct  for  the  larvae,  does  not  pretend  to  indi-  «lMlnt.. 

cate  the  true  form  of  the  developed  organ.     Males  unknown. 

Habitat:  Clean  "white"  marine  sand,  in  five  feet  of  water,    x  500 
from  a  cove  near  the  entrance  to  Buzzard's  Bay,  Mass.,  U.  S.  A.,     Also  from 
"sea-grass,"  Key  West,  Florida.     Fig.  83. 

84.  Doryllium  uniforme  n.  sp.  Cuticle  naked,  very  minutely  transversely  stri- 
ated. Neck  conoid.  Spear  minute,  dorylaimoid,  but  with  a  distinct,  somewhat 
refractive  posterior  swollen  part.  The  oesophagus  continues  with  slight  vari- 
ations until  it  joins  the  pineapple-shaped  cardiac  bulb,  which  is  two-thirds  as 
wide  as  the  base  of  the  neck  and  is  separated  from  the  preceding  portion  of  the 
oesophageal  tube  by  a  constriction.  This  bulb  contains,  among  other  things, 
a  spherical  nucleus  with  a  distinct  nucleolus,  presumably  indicating  the  exis- 
tence here  of  glands  like  those  of  Dorylaimus.  The  narrow  intestine  joins  the 
middle  of  the  posterior  surface  of  the  bulb,  and  becomes  at  once  about  two-fifths 


304 


ORDER   AXONCHIA 


X750 


ndtm 


as  wide  as  the  body;  its  cross-section  would  present  only  about  two  cells.  These 
cells  contain  scattered  yellowish  granules  of  uniform  size.  From  the  incon- 
spicuous anus  the  rectum  extends  a  distance  longer  than  the  anal  body-diaineter. 
The  pre-rectum  is  about  four  times  as  long  as  the  corresponding  body-diameter, 
rmJb  K  *rm  V*  JftJfr^V*  -4  9.5  19.  '-si."  97.  and  is  readily  distin- 

X  ^  "  gUished  from  the  rest  of 

.4  12.  19.  -x-1  96.  gz  the  intestine  by  differ- 
l-  2-4  '^  2-«~rx,i.  "ences  in  structure;— it 
appears  more  transparent  and  more  nearly  colorless. 
Renette  unknown.  There  seem  to  be  very  faint  indi- 
cations of  the  presence  of  a  lateral  wing.  The  lateral 
fields  are  about  one-fifth  to  one-fourth  as  wide  as  the 
body.  From  the  rather  inconspicuous  vulva,  the 
vagina,  which  is  well  cutinized,  extends  inward  and 
'backward  half  way  across  the  body,  where  it  joins  the 
single  uterus  which  extends  backward.  The  reflexed 
'ovary  reaches  half  way  back  to  the  vulva,  and  con- 
tains ten  to  twenty  ova  arranged  for  the  most  part  single  file.  There  is  an  ante- 
rior rudimentary  branch  to  the  uterus  which  is  a  little  longer  than  the  corre- 
sponding body-diameter.  Eggs  unknown;  judging  from  the  full-grown  ova  they 
are  about  as  long  as  the  body  is  wide  and  about  half  as  wide  as  long.  Single  male 
supplement  two  body-diameters  in  front  of  the  anus,  four  times  as  far  away  as 
the  anal  pair. 

Habitat:  Brackish  soil  on  the  banks  of  a  marine  estuary,  Los  Patos,  California, 
U.  S.  A.  Differs  from  Dorylaimus  in  the  form  of  the  spear,  and  the  oesophagus. 
Most  species  of  Dorylaimus  have  two  ovaries.  Differs  also  in  the  reduced  num- 
ber of  supplementary  organs; — outside  the  anal  pair,  there  is  only  one.  Differs 
in  material  respects  also  from  Tylencholaimus.  to  which  it  may  be  compared. 
Fig.  84. 

.7        7.2  ;    20.         "'??'"       99- 

85.  Leptonchus  granulosus  n.  sp.  L-~  2;5  J-  3'4  2-^  "  Cuticle  naked, 
its  transverse  striae  resolvable  with  difficulty  into  exceedingly  minute  dots. 
One  of  the  inner  striae  seems  to  correspond  to  about  four  of  the  outer.  Cuticle 
also  possessed  of  inconspicuous  longitudinal  striae.  Neck 
conoid.  Amphids  broad,  faint,  somewhat  stirrup-shaped,  fP 
their  anterior  contours  opposite  the  labial  constriction.  The 
oesophagus  begins  as  a  tube  about  one-fourth  as  wide  as  the 
base  of  the  head,  and  continues  to  have  this  diameter  until 
it  finally  expands  to  form  the  clavate  or  elongated  pyriform 
cardiac  swelling,  which  is  about  one-half  as  wide  as  the  base 
of  the  neck.  There  is  an  inconspicuous  conoid  cardia  about 
one-third  as  wide  as  the  body.  The  oesophagus  is  therefore 
essentially  tubular  throughout  most  of  its  length.  It  is,  or. 
however,  a  trifle  wider  near  the  middle,  in  the  neighborhood 
of  the  nerve-ring,  usually  behind  it,  and  at  this  point  there 
appears  to  be  a  slight  alteration  in  the  lining,  suggesting  in  the  faintest  possible 
manner  vestiges  of  a  median  bulb ;  at  its  widest  part,  however,  the  slender  part 
of  the  oesophageal  tube  is  not  more  than  one-fourth  to  one-fifth  as  wide  as  the 
corresponding  portion  of  the  neck.  At  its  narrowest  part,  just  in  front  of  the 
cardiac  swelling,  it  is  about  half  as  wide  as  it  is  at  its  widest  part.  The  lining 
of  the  oesophagus  is  not  a  conspicuous  feature.  The  intestine,  which  becomes 
at  once  fully  three-fourths  as  wide  as  the  body,  is  made  up  of  cells  of  such  a  size 


LEPTONCHUS,    AXONCHIUM 


305 


that  its  cross-section  presents  but  two  of  them.  These  cells  are  packed  with 
granules  of  variable  size,  the  largest  having  a  diameter  one-eighth  as  great  as 
that  of  the  body,  while  the  smallest  are  very  minute.  The  tail  begins  to  taper 
from  some  distance  in  front  of  the  anus.  There  are  a  few  inconspicuous  papillae 
near  the  posterior  extremity  of  the  tail  of  the  female.  The  pre-rectum  is  of 
most  unusual  length,  extending  to  a  little  beyond  the  flexure  of  the  anterior 
ovary,  and  hence  occupying  about  half  the  length  of  the  body.  It  is  set  off  from 
the  front  portion  of  the  intestinal  tube  by  a  distinct  constriction,  and  differs  also 
in  structure.  The  lateral  fields  are  about  one-third  as  wide  as  the  body.  The 
ventral  fields  appear  to  be  wider  than  the  lateral,— nearly  half  as  wide  as  the  body, 
at  least  appearances  half  way  between  the  vulva  and  the  anus  give  rise  to  this 
measurement.  The  traces  of  the  excretory  pore  are  difficult  to  observe,  but  they 
are  uniform  in  the  different  specimens,  and  as  no  other  similar  "break"  in  the 
cuticle  is  to  be  deciphered  it  seems  impossible  that  the  single  "break"  opposite 
the  nerve-ring  can  be  anything  but  an  excretory  pore.  No  indications  are  seen 
of  the  existence  of  an  internal  structure  connecting  with  this 
pore,  but  the  neck,  especially  the  posterior  portion  of  it  in  front 
of  the  cardiac  swelling,  is  occupied  by  elongated  structures, 
which  may  be  of  a  glandular  nature  and  connected  with  the 
aforesaid  "pore."  The  slightly  elevated  vulva  is  a  trans- 
verse  slit  about  one-fourth  as  long  as  the  body  is  wide.  Radi- 
ating from  its  ends  are  four  muscles  passing  to  the  submedian 
fields.  The  vagina  leads  about  halfway  across  the  body.  The 
reflexed  ovaries  reach  about  three-fourths  the  distance  back  to 
the  vulva,  and  contain  a  dozen  or  more  developing  ova, 
arranged  somewhat  irregularly.  The  elongated  eggs  are  three 
to  four  times  as  long  as  the  body  is  wide,  and  about  one-fourth 
to  one-fifth  as  wide  as  long. 

Habitat:  Soil  about  willow  trees,  Arlington  Farm,  Va.,  oppo- 
site the  city  of  Washington,  D.  C.,  U.  S.  A.     Fig.  85,  p.  304. 

.2         6.7      34.  55'"        98.8     9  9 

86.  Axonchium  amplicollen.  sp.  '6  (7)/1'9  2'8 
Cuticle  naked.  The  two  portions  of  the  ]b(6) 
oesophagus  are  separated  by  a  constriction, 
as  shown  in  the  figure;  both  parts  cylindri- 
cal. Lining  of  the  oesophagus  well-devel-  aaiP" 
oped,  but  more  or  less  obscured  by  the 
well  marked,  rather  coarse,  colorless  muscu- 
lature in  the  posterior  part.  Salivary  glands 
in  the  posterior  part  of  the  oesophagus  as  in 
Dorylaimus,  one  gland  emptying  into  the 
lumen  near  the  anterior  portion  of  the 
larger  cylindroid  half  of  the  oesophagus, 
the  others  farther  back.  Anus  subcon- 
tinuous;  the  rectum  prominent  and  cutin- 
ized,  and  one  and  one-third  times  as  long 
as  the  anal  body-diameter.  The  anal  mus-  x750 
cles  are  clearly  disclosed.  The  pre-rectum  is  five  times  as  long  as  the  anal  body- 
diameter,  and  set  off  by  a  definite  but  faint  constriction.  The  cells  of  the  intes- 
tine contain  numerous,  colorless  granules  of  variable  size,  the  largest  of  which 
are  one-twenty-fifth  as  wide  as  the  body.  Tail  of  the  adult  female  as  shown  in 
the  illustration.  In  the  youngest  larvae,  however,  the  tail  is  cylindroid  in  the 


pplWIS) 


mscon 


air  mi 


ml 


mar 


as- 


306  ORDER   AXONCHIA 

posterior  half,  and  in  this  part,  about  one-third  as  wide  as  at  the  anus,  the  ter- 
minus being  rounded.  The  coarsely  granular  lateral  fields  are  one-fourth  to 
one-sixth  as  wide  as  the  body.  Renette  problematical.  From  the  small,  incon- 
spicuous, faintly  elevated  vulva,  the  rather  weak,  non-cutinized  vagina  leads 
inward  two-fifths  the  distance  across  the  body.  The  elongated  eggs  are  three 
times  as  long  as  wide  and  twice  as  long  as  the  body  is  wide.  The  tapering  ovary 
reaches  about  half  way  back  to  the  vulva,  and  contains  about  twenty  ova.  the 
largest  of  which  are  arranged  single  file,  while  the  others  are  arranged  irregularly. 
Habitat:  Soil  about  the  roots  of  Luca  da  Persia,  Brazil.  The  part  of  Brazil 
from  which  the  plants  came  is  unknown.  The  soil  examined  was  removed  from 
the  roots  after  they  were  imported  into  the  United  States.  It  is  probable  that 
the  species  is  syngonic.  Another  tropical  species,  originally  described  by  the 
writer  under  the  name  of  Dorylaimus  longicollis,  from  about  banana  roots,  Fiji, 
possibly  also  belongs  to  this  genus.  Fig.  86.  p.  305. 


87.  Onchulella  ocellata  n.  sp.  1.2  i.*  1.6  1.7  1.3  "  Cuticle  naked. 
Striae  almost  impossible  of  resolution.  Spear  solid,  refractive  and  apparently 
"structureless"  throughout.  The  two  yellowish  ocelli  are  wide  apart,  their 
lenses  colorless.  The  oesophagus  is  at  first  about  one-half,  near  the  nerve  ring 
two-fifths,  and  finally  five-sixths,  as  wide  as  the  corresponding  portion  of  the 
neck;  the  anterior  part  is  cylindroid,  the  posterior  part  more  or  less  obscure. 
The  oesophageal  region  seems  to  be  largely  filled  with  a  series  of  elongated, 
clavate  glands,  some  granular  and  some  not,  and  hence  of  two  kinds.  The  hind- 
ermost  of  these  is  the  largest,  and  with  reference  to  the  oesophagus  lies  in  much 
the  same  way  as  the  larger  salivary  gland  of  Tylenchus.  There 
is  also  a  large  spherical  nucleus  in  this  gland,  as  in  Tylenchus. 
This  is  the  only  one  of  the  granular  cells  having  a  large  conspicu- 
ous  nucleus.  The  non-granular  cells  are  smaller;  two  or  three 
of  them  present  nuclei.  The  measurements  given  in  the  formula 
for  the  base  of  the  oesophagus  really  refer  to  the  posterior  limits 
of  these  glands.  Just  in  front  of  the  ocelli  there  are  two  lateral, 
external,  elliptical,  cuticular  elements,  two-thirds  as  long  as 
the  corresponding  diameter  of  the  neck,  and  one-third  as  wide 
as  long.  These  connect  backward  by  means  of  ducts,  and  it 
seems  probable  that  they  are  connected  with  one  of  the  two  kinds  of  glandular 
cells  contained  in  the  neck.  The  lining  of  the  oesophagus  is  indistinct,  its  mus- 
culature fine  and  colorless.  No  cardia  has  been  seen.  The  thick-walled  intes- 
tine, which  has  a  distinct,  refractive,  ziz-zag  lining,  becomes  at  once  five-sixths 
as  wide  as  the  body.  The  anterior  lip  of  the  anus  is  more  or  less  elevated.  The 
inconspicuous  rectum  is  about  three-fourths  as  long  as  the  anal  body-diameter; 
anal  muscles  are  dimly  to  be  seen.  The  cells  of  the  intestine,  of  which  only  two 
to  three  would  be  presented  in  cross-section,  are  packed  with  colorless  granules 
of  variable  size,  the  largest  of  which  are  one-fifteenth  as  wide  as  the  body.  The 
arcuate  tail  tapers  from  the  anus  to  the  terminus,  and  presents  a  spinneret 
about  one-sixth  as  wide  as  its  base.  Caudal  glands  tandem  in  front  half  of  tail. 
No  caudal  setae.  Renette  unknown.  From  the  somewhat  depressed  vulva,  the 
more  or  less  cutinized  vagina  extends  inward  three-fifths  the  distance  across  the 
body.  An  ovum,  apparently  full-grown  and  about  to  enter  the  uterus,  is  twice 
as  long  as  the  body  is  wide,  and  one-third  as  wide  as  long. 

Habitat:  Eel-grass,  Biscayne  Bay,  Miami,  Florida,  U.  S.  A.     Flemming  to 
glycerine  jelly.     Only  one  specimen— that,  a  shrunken  one— seen.     Fig.  87. 


CAMPYDORA  307 

XIII.     Order  Anaxonchia 

.6      12.2      33.          "56  85. 


88.  Campydora  demonstrans 
Eight  longitudinal  striations  exist  throughout  the  length  of  the  body.     In  cer- 
tain parts,  especially  along  the  neck,  the  longitudinal  striae  are  more  marked 
than  elsewhere,  attaining  almost  the  magnitude  of  wings.     There  appear  to  be 
four  such  "wings,"  but  an  exact  count  has  not  yet  been  made.     Neck  conoid. 
There  are  six  rounded,  somewhat  flat,  partly  confluent  lips,  bearing  two  circlets 
of  labial  papillae,  as  shown  in  the  illustration.     These  are  plainly  innervated, 
and  are  of  the  sort  commonly  seen  in  Dorylaimus.     The  inner  circlet  has  six 
members;  the  outer  circlet  twelve,  i.e.,  six  pairs.     The  six  slender  structures 
extending  forward  around  the  mouth,  the  inner  circlet,  may  also  end  in  organs 
having  the  nature   of   papillae,  but  if  so,   they  are  of  a  different   character 
from  the  outer  papillae.     Base  of  the  solid  onchium  axial,  m 
or  nearly  so,  the  apex  however,  bent  considerably  to  the  dorsal 
side.     The  onchium  may  be  protruded  by  means  of  longitudi- 
nal  muscles  composing  the  pharyngeal  bulb.     Lining  of  the 
posterior  portion  of  the  pharynx  considerably  less  refractive. 
The  oesophagus  has  about  the  same  relative  diameter  until  it 
finally  expands  suddenly  to  form  the  somewhat  elongated,  msc 
cylindroid  cardiac  bulb,  which  is  fully  five-sixths  as  wide  as 
the  corresponding  portion  of  the  neck,  and  contains  a  rather 
faint,    elongated,    three-parted  valve  occupying   about   half  XTSO 
the  optical  longitudinal  section.     This  cardiac  bulb  has  a  peculiar  formation  in 
that  the  valve  extends  very  nearly  from  end  to  end  of  the  bulb  and  is  manifestly 
triquetrous,  so  that  by  the  contraction  of  the  radial  muscles,  the  bulb  can  be 
thrown  into  the  form  of  a  chamber.     Lining  of  the  oesophagus  unusually  distinct. 
The  central  oesophageal  tube,  when  seen  in  optical  section  presents  each  of  its 
walls  with  a  double  contour,  and  the  lumen  has  about  the  same  width  as  the 
thickness  of  the  walls.     The  entire  width  of  this  tube  is  considerably  greater 
than  the  thickness  of  the  cuticle,  and  is  about  equal  to 'one- twelfth  the  diam- 
eter of  the  middle  of  the  neck.     The  intestine  becomes  at  once  about  five-sixths 
as  wide  as  the  body.     There  is  a  comparatively  distinct,  broad,  low  cardia. 
The  walls  of  the  intestine  are  comparatively  thick.     Its  cross-section  would 
probably  present   two  to   four  cells.     These   cells  contain   doubly-refractive, 
spherical,  scattered  granules  of  variable  size,  the  largest  of  which  have  a  diam- 
eter one-tenth  as  great  as  that  of  the  body,  the  smallest  being  very  much  smaller. 
When  seen  with  crossed  Nicols,  these  granules  show  a  prominent  St.  Andrew's 
cross.     All  the  granules  appear  to  be  of  the  same  character;  their  walls,  seen  in 
optical  section,  present  a  double  contour.     Behind  the  base  of  the  neck  for 
a  distance  about  equal  to  one  body-diameter,  the  granules  are  few  in  number 
and  small  in  size.     Elsewhere,  they  are  about  equally  distributed,  or  perhaps  a 
little  less  abundant  toward  the  posterior  end.     The  tail  is  conoid  from  near 
the  anus,  and  the  cuticle  becomes  thicker  on  the  posterior  extremity  and  more 
strongly  striated.     In  young  specimens  it  expands  laterally  to  form  wings, 
which  appear  quite  distinctly  striated  when  viewed  dorso-ventrally.     From 
the   conspicuous,    depressed   anus,    the   strongly   refractive,    cutinized   rectum 
is  considerably  longer  than  the  anal  body-diameter.     Excretory  pore  depressed 
and  rather  conspicuous.     From  it,  the  cutinized  duct  can  be  distinctly  seen 
leading  inward.     From  the  depressed  somewhat  circular  vulva,  the  cutinized 


ORDER   ANAXONCHIA 


3>2'2"  Naked  cuti- 


vagina  leads  inward  nearly  half  way  across  the  body,  where  it  joins  the  single 
uterus,  which  apparently  extends  forward.     The  ovary  extends  backward  past 
the  vulva.     Nothing  is  known  concerning  the  size  and  form  of  the  eggs. 
Habitat:  About  the  roots  of  citrus  trees,  Corfu,  Greece.    Fig.  88,  p.  304. 

(1.1)15.        12.  22.  "5S.1' 

89.  Catalaimusacuminatus  n.sp-   <-9)/i.9     i.s      1.9          z-4 
cle  traversed  by  exceedingly  fine  transverse  striae.     Lips  when  closed  exhibiting 

about  a  dozen  folds  which 
are  barely  visible  with  the 
,  highest  powers.  Onchium 
arcuate,  slender,  long, 
spear-like.  Eye-spots 
two,  lateral,  refractive, 
„,  colorless,  glistening. 

|  set CTT  Near  the  beginning  of  the 
pharyngeal  tube,  each  of 
' x  75°  the  three   sectors   of  the 

oesophagus  presents  longitudinal  lines  of  yellowish  pigment. 
From  some  little  distance  behind  the  nerve-ring,  the  oesoph- 
agus continues  to  have  the  same  diameter  throughout  the 
remainder  of  its  length.  There  is  a  flattish  conoid  cardia, 
about  one-third  as  wide  as  the  base  of  the  neck.  Lining  of  the  oesophagus  appar- 
ently wavy,  occupying  one-third  of  the  optical  section.  The  intestine,  which 
becomes  at  once  three-fourths  as  wide  as  the  body,  is  made  up  of  cells  of  large 
size,  at  least  some  of  the  cells  are  of  very  large  size,— of  such  a  size  that  probably 
two  only  would  be  required  to  build  a  circumference.  Whether  there  are  other 
smaller  cells  scattered  among  these  larger  cells  remains  to  be  determined.  The 
large  cells  are  packed  with  nearly  colorless  granules  of  rather  uniform  size,  hav- 
ing a  width  about  half  as  great  as  the  thickness  of  the  body  wall.  While  the  anus 
is  depressed,  its  posterior  lip  is  slightly  raised.  Rectum  about  as  long  as  the 
anal  body-diameter.  The  nema  tapers  gradually  from  a  considerable  distance 
in  front  of  the  anus.  Near  the  anus,  it  begins  to  taper  more  rapidly,  so  that  at 
the  middle  of  the  tail,  the  diameter  is  only  about  half  as  great  as  at  the  anus; 
thence  onward,  the  tail  is  nearly  cylindroid  and  ends  in  an  elongated  spinneret. 
No  distinct  traces  of  caudal  glands  are  to  be  seen  in  the  base  of  the  tail;  hence 
it  is  assumed  that  they  are  located  in  front  of  the  anus.  Obscure  indications 
have  been  seen  of  their  presence  half  as  far  in  front  of  the  anus  as  the  terminus 
is  behind  it.  The  lateral  fields  have  not  been  distinctly  seen.  The  location  of 
the  renette  cell  remains  undetermined.  This  description  is  derived  from  a 
young  female,  and  all  that  can  be  said  is  that  the  ovaries  are  probably  double 
and  reflexed. 

Habitat:  Marine  mud  and  sand,  Noumea,  New  Caledonia,  and  Biscayne  Bay, 
Fla.,  U.  SL  A.  Other  species  of  this  genus  occur  in  the  Indian  Ocean  and  in  the 
Mediterranean  Sea.  Fig.  89. 

90.  Bolbella  tenuidens  n.  sp.     Transverse  striae  excessively  fine,  more  readily 
seen  in  the  subcuticle  with  high  powers  under  fav- 
orable   conditions.     Longitudinal    striations    are  — — — — — —  —  >2.9  .. 

present  throughout  the  length  of  the  body.     Body  >3' 

wall  massive,  occupying  one-third  the  radius.     As  -;     9-      19-          '*' —22.7  - 

compared  with  related  species  the  anterior  cham-  '4 

ber  of  the  pharynx  is  somewhat  more  foreshortened.     There  are  two  to  three 


BOLBELLA 


309 


dozen  very  long  and  very  slender  cervical  setae,  those  toward  the  head  end 
being  nearly  twice  as  long  as  the  cephalic  setae, — more  of  them  than  are  shown 
in  the  illustration.  Glandular  tissue  exists  in  the  oesophagus,  the  granular 
branches  of  which  may  be  seen  more  particularly  between  the  oesophageal  bulbs: 
a  duct  appears  to  lead  to  the  pharynx.  A  cross-section  of  the  intestine  would 
present  four  to  six  cells.  In  the  female,  from  the  more  or  less  continuous  anus, 
of  which,  however,  the  posterior  lip  is  slightly  elevated,  the  inconspicuous  rec- 
tum extends  inward  a  distance  equal  to  the  anal  body-diameter.  A  narrow  ren- 
ette  cell  exists  two  to  three  body  widths  behind  the  cardia  on  the  ventral  side. 
The  slightly  elevated  vulva  is  of  medium  size,  and  leads  to  a  large  tubular  vagina, 
at  first  at  right  angles  to  the  ventral  surface  and  then  leading  obliquely  forward. 
The  wall  of  the  vagina  is  well  cutinized.  Each  branch  of  the  two-horned  uterus 
is  about  one  and  one-half  times  as  long  as  the  body  is  wide.  Two  eggs  have 
been  seen  in  a  uterus  at  one  time,  each  about  twice  as  long  as  the  body  is  wide. 
The  spherical  spermatozoa  existing  in  the  uterus  are  about  one-sixteenth  as  wide 
as  the  body.  The  broad,  more  or  less  cylindroid  ovaries  extend  two-fifths  the 
way  back  to  the  vulva,  and  contain  eight  to  ten  countable  ova  arranged  for  the 
most  part  irregularly.  The  two  supplementary  organs  of  Bolbella,  like  the  simi- 
lar organs  of  Eurystoma,  are  connected  with  large  glands,  one  to  each  supple- 
ment. One  of  these  glands  is  very  well  shown  in  the  illustration  at  gl  sup  cf. 


ait  lumoe 


FIG.    90.     Bolbella  tenuidens. 
Details   of    the     pharynx    are 
shown  X  1500  on  the  following 
There  are  other  species 
of  Bolbella. 


dctm 


x225 


dctq 
mi      copmsc    thtglsup 


The  gland  is  long  and  unicellular  and  its  nucleus  is  shown  at  ncl  gl.  A  natural 
supposition  is  that  these  two  supplements  are  cup-shaped  organs  attachable  by 
suction.  The  supposition  appears,  at  first  thought,  to  find  support  in  the  exis- 
tence of  the  "anchors,"  which  are  manipulated  by  special  muscles.  It  is  rather 
difficult  to  harmonize  this  theory  with  the  existence  of  such  large  glands,  so 
much  so  that  one  feels  inclined  to  give  up  all  idea  that  suction  plays  any  part 
in  the  functioning  of  these  organs.  The  so-called  cups  of  the  supplements  are 


310  ORDER   ANAXONCHIA 

to  a  considerable  extent  protrusile,  just  as  in  Eurystoma.     The  males  of  Bol- 
MqthllOl  bella  seem  to  be  considerably  less  common  than 
the  females. 

Habitat:  Sand,  Bathing  Beach,  Woods  Hole, 
Mass.,  U.  S.  A.  Flemming  to  glycerine  jelly. 
.  Sublimate  to  balsam.  Resembles  Symplocos- 
toma  Bastian,  but  differs  materially  in  the 
structure  of  the  posterior  part  of  the  oesoph- 
agus, as  well  as  in  the  absence  of  eye-spots. 
The  males  of  Symplocostoma  have  no  sup- 
plements. 

The  strongly  tapering  neck  of  Bolbella  results 
in  a  head  of  small  size.     Notwithstanding  its 
small  size,   one   is  immediately  struck  by  its 
strong  resemblance  to  the  head  of  Eurystoma. 
The  following  differences,  however,  are  to  be 
^m  siilm  dxt  noted.     The  amphid  is  smaller  and  of  a  differ- 
ent form,  though  here  also,  as  in  Eurystoma, 
/V/   located  on  the  dorsal  side  of  the  lateral  lines. 
While  the  pharynx  is  divided  into  two  more  or 
xlSOO   less  distinct  chambers,  the  division  line  is  not 
marked  by  transverse  rows  of  denticles.     Fig.  90a,  p.  309;  Fig.  906. 

91.  Thoonchus  ferox  n.  sp.  Striae  resolvable  with  difficulty.  The  thin,  color- 
less lips  are  arched  over  the  pharynx  as  in  Oncholaimus,  but  the  minute  flaps 
often  seen  on  the  tips  of  the  lips  of  Oncholaimus 

appear  to  be  absent  in  this  species,  or  at  any      — — ^ — ^ '-—^ — 5^_>2.2.. 

rate,  much  reduced.     Labial  papillae  located  in 

the  midst  of  shallow  depressions.    Amphids  faint.     ii| — -£| — ^ """6  7^9^>2.i.. 

Pharynx  denticulate.     The  oesophagus  has  the 

same  diameter  throughout  its  anterior  half,  after  which  it  begins  slowly  to  expand 
and  finally  is  two-thirds  as  wide  as  the  base  of  the  neck.  There  is  a  distinct, 
bluntly  convex-conoid  cardia,  nearly  half  as  wide  as  the  base  of  the  neck.  The 
intestine,  which  is  separated  from  the  oesophagus  by  a  deep  constriction,  becomes 
at  once  three-fourths  as  wide  as  the  body.  It  is  rather  thin  walled  and  in  cross 
section  presents  about  six  cells.  These  cells  contain  scattered,  yellowish  gran- 
ules of  variable  sizes,  so  arranged  as  to  give  rise  to  an  obscure  tessellated  effect. 
The  largest  granules  have  a  diameter  nearly  equal  to  the  thickness  of  the  body 
wall.  Posterior  lip  of  the  anus  strongly  elevated.  Rectum  equal  in  length  to 
the  anal  body-diameter.  Renette  elongated,  located  a  little  distance  behind 
the  cardia.  The  lateral  fields  appear  to  be  rather  narrow;  they  are  character- 
ized by  the  presence  in  them  of  numerous,  rather  scattered,  yellowish  granules, 
which  are  more  numerous  toward  the  edges  of  the  field,  and  which,  therefore, 
define  the  fields  more  distinctly  than  is  usually  the  case.  At  the  base  of  the 
head,  the  fields  are  seen  to  widen  out  and  terminate  in  a  rounded  contour;  the 
margin  of  this  contour  marks  the  position  of  the  amphids.  The  granules  found 
along  the  lateral  fields  appear  also  in  longitudinal  rows  outside  these  fields. 
Thus,  on  either  side  of  the  lateral  fields,  there  is  a  single  distinct  row  of  these 
granules;  on  the  submedian  line,  another  very  distinct  assemblage  of  granules, 
consisting  of  several  irregular  rows.  Then  comes  another  scattered  faint  row; 
then  a  ventral  or  sub-ventral  assemblage  consisting  of  several  rows.  There  is 
thus  produced  on  the  neck  as  well  as  elsewhere  quite  a  distinct  longitudinal 


THOONCHUS 


311 


"striping"  whose  presence  is  indicated  mainly  by  the  arrangement  of  these 
minute  yellowish  granules.  The  stout  tail  diminishes  rapidly  from  the  posterior 
lip  of  the  anus,  so  that  at  the  middle  it  has  a  diameter  about  two-thirds  as  great 
as  at  the  base;  thence  onward  it  is  nearly  cylindroid  to  the  rounded  terminus. 
The  caudal  glands  are  located  in  a  tandem  series  considerably  in  front  of  the 
anus;  the  hindermost  being  about  four  times  as  far  from  the  anus  as  the  termi- 
nus. The  two  anterior  glands  are  close  together  and  are  nearly  as  far  in  front 
of  the  hindermost  as  this  latter  is  in  front  of  the  anus.  From  the  elevated  vulva, 
the  vagina  extends  inward  half  way  across  the  body.  The  ovaries  reach  about 
one-third  the  distance  back  to  the  vulva  in  specimens  that  contain  three  eggs 
in  the  uterus.  Eggs  elongated,  about  twice  as  long  as  the  body  is  wide  and  about 
one-third  as  wide  as' long.  Each  of  the  twc  uteri  may  contain  three  eggs  at  one 
time.  Tail  of  the  male  more  strongly  arcuate  than  that  of  his  mate.  Clavate 
caudal  glands  about  as  long  as  the  body  is  wide  and  about  one-third  as  wide  as 
long,  arranged  some  distance  apart  in  a  tandem  series.  When  the  body  of  the 
male  is  closely  coiled,  the  ventral  surface  toward  the  posterior  end  becomes 
corrugated  in  a  definite  way  for  some  distance  in  front  of  the  anus,  suggesting 
that  this  area  may  be  systematically  innervated  and  serve  the  purpose  of  a  ven- 
tral series  of  about  two  dozen  subequidistant  supplementary  organs.  These 
corrugations  are  apparently  innervated,  but  no  distinct  corresponding  breaks 
or  openings  have  been  seen  in  the  cuticle.  On  the  ventral  side  at  a  distance 
in  front  of  the  anus  three  times  as  great  as  the  length  of  the  tail,  there  is  an 
elevated  supplementary  organ  in  the  form  of  a  transverse  ridge.  This  occurs 
in  the  midst  of  the  corrugations  just  described, — at  least,  it  appears  that  the 
corrugations  extend  beyond  it,  although  they  are  not  quite  so  close  together 
or  so  marked  in  this  region.  This  supplementary  organ  begins  near  the  sub- 
median  lines  and  extends  across  the  ventral  region.  Its  internal  structure  has 
not  been  satisfactorily  elucidated.  It  appears  probable  that  the  cuticle  on 

the  ventral  line  ^          mSllIm(txt\setCph(JOi  dd      CBBBte^^^ *SE  S* 

is  interrupted, 
but  even  this  is 
not  clearly  es-  " 
tablished.  This 
swelling  has  two 
to  three  times 
the  width  of  the 
corrugations  and 
occurs  at  the 
same  position  on 
three  different 

male   specimens, 

X750 


extn 


so    there  can  be 

no  doubt  about  its  being  a  distinct  supplementary  structure.  Opposite  the 
middle  of  the  spicula,  also,  there  is  a  pair  of  subventral  supplementary  papillae, 
accompanied  by  slender  subventral  setae  in  the  rear.  There  are  a  few  short 
delicate  setae  on  the  tail,  especially  on  the  submedian  lines,  but  also  in  front  of 
the  anus  for  some  distance,  where  they  are  longer,— more  nearly  the  size  of 
those  on  the  anterior  extremity.  About  a  dozen  pairs  of  copulatory  muscles 
occur  in  the  ventrally  submedian  region,  in  a  space  four  to  five  times  as  long  as 
the  tail.  Testes  relatively  small. 

Habitat:  Open-ocean  beach-sand,  South  California.     Bay  City,  Huntington 
Beach   U.  S.  A.     Fig.  91. 


312  ORDER   ANAXOXCHIA 


92.  Trilepta  guttata  n.  sp.  -J.  -5  -5  .5  ~~N  .4>(?!5-4"  Cuticle  naked  except 
for  the  cephalic  and  cervical  setae.  Lips  probably  three,  and  double,  rather  thick 
and  well-developed.  When  closed  the  pharynx  appears  as  if  longitudinally 
ribbed.  This  appearance,  however,  may  be  due  to  the  folding  of  the  rather 
massive  lips,  which  close  together  and  form  a  vestibule  nearly  one-half  as  long 
as  the  remainder  of  the  pharynx.  Neck  cylindroid.  The  cylindroid  oesophagus 
near  the  nerve-ring  is  one-half,  and  also  finally  one-half,  as  wide  as  the  base  of 
the  neck;  its  musculature  is  fine  and  its  lining  indistinct.  There  is  an  indistinct 
cardia  one-third  as  wide  as  the  base  of  the  neck.  The  thick-walled  intestine, 
set  off  by  a  collum  two-fifths  as  wide  as  the  neck,  and  presenting  a  faint  lumen, 
becomes  at  once  two-thirds  as  wide  as  the  body,  and  in  cross-section  is  made 
up  of  but  few  cells  containing  scattered  to  numerous,  small,  more  or  less  uniform, 
yellowish  granules.  Neither  spinneret  nor  caudal  glands  have  been  distinctly 
seen.  The  lateral  fields  are  one-fourth  as  wide  as  the  body.  Renette  unknown. 
From  the  raised  anus  the  tail  diminishes  rather  suddenly,  then  tapers  gently  to 
the  middle,  where  it  is  about  one-half  as  wide  as  at  the  base;  thence  onward  it  is 
cylindroid  to  the  terminus,  which  is  one-third  as  wide  as  the  base  of  the  tail. 
The  two  simple,  slender,  rather  frail  and  more  or  less  tapering,  acute  to  sub-acute 
spicula  are  arcuate  or  somewhat  bent,  and  are  one  and  one-half  times  as  long 
set  Ib  set  Jot  as  the  anal  body-diameter.  Viewed  in  profile  their 
proximal  ends  appear  to  lie  dorsad  from  the  body- 
axis.  The  inconspicuous  accessory  piece  lies  paral- 
lel to  the  spicula.  There  are  no  supplementary 
organs.  The  ejaculatory  duct  is  one-third,  the  vas 
deferens  one-half,  as  wide  as  the  body.  The  cyl- 
indroid testis  is  one-half  as  wide  as  the  body,  even 
at  its  rounded,  blind  end.  Oblong,  fusiform,  chro- 
matin  masses  are  to  be  seen  in  the  sperm  cells. 
IIM  OP  Habitat:  Sand,  below  low-tide  mark  Bathing 
Beach,  Woods  Hole,  Mass.,  U.  S.  A.  Sublimate  to  balsam.  Fig.  92. 


93.  Anoncholaimus  mobilis  n.  sp.  l-V  ^  l-6  *•"*  l-z  "The  cuticle  is 
so  very  thin  that  it  wrinkles  on  the  inside  of  the  curve  when  the  body  bends. 
Though  there  are  no  true  wings,  there  is  a  faint,  clear  wing-space  about  one-eighth 
as  wide  as  the  body.  The  thin,  flat  lips  resemble  those  of  Oncholaimus.  There 
is  a  vestigial  dorsal  onchium  opposite  the  bases  of  the  cephalic  setae, — faintly 
shown  in  the  illustration.  The  neck  is  cylindroid.  In  the  oesophagus  near  the 
base  of  the  pharynx  there  are  scattered  yellowish  granules.  The  oesophagus  is  a 
little  wider  at  both  ends  than  elsewhere.  Near  the  pharynx  it  is  two-thirds,  at 
the  nerve-ring  two-fifths,  and  finally  three-fifths,  as  wide  as  the  corresponding 
portion  of  the  neck.  It  has  a  distinct,  refractive,  apparently  corrugated  lining; 
among  its  radial  muscles  there  is  more  or  less  of  yellow  pigmented  matter,  which 
occurs  in  straightish  radial  lines.  There  are  at  least  two  submedian  glands  in 
the  tissues  of  the  oesophagus,  emptying  at  the  pharynx.  The  thick-walled  intes- 
tine is  set  off  by  a  constriction  half  as  wide  as  the  neck,  and  has  a  faint  ziz-zag 
lumen;  it  becomes  at  once  two-thirds  as  wide  as  the  body,  and  in  cross-section 
presents  about  ten  to  twelve  cells.  There  are  numerous  yellow  granules  of  vari- 
able size  in  the  cells  of  the  intestine,  the  largest  being  one-thirtieth  as  wide  as 
the  body;  owing  to  their  arrangement  there  is  a  faint  tessellated  effect.  From 
the  anus,  the  posterior  lip  of  which  is  elevated,  the  rather  prominent  rectum 
extends  a  distance  one  and  one-fourth  times  as  great  as  the  anal  body-diameter. 


ANONCHOLAIMUS,    ONCHULUS 


313 


The  convex-conoid  tail  tapers  from  the  anus  to  the  spinneret,  which  is  armed 
with  submedian  setae.  The  caudal  glands  lie  in  front  of  the  anus.  There  are 
practically  no  caudal  setae.  The  lateral  fields  are 
two-fifths  as  wide  as  the  body  and  contain  large 
ain/)/l  ce^ular  elements.  Anoncholaimus  has  eight  cervi- 
cal glands,  six  emptying  into  the  anterior  part  of 
the  pharynx  opposite  the  bases  of  the  setae  and  two 
smaller,  a  little  farther  back,  on  the  dorsally  sub- 
lateral  lines.  The  granular  contents  of  the  ducts 
of  these  glands,  increased  slightly  in  volume,  form 


move  back  and  forth  during  the  various  movements 
of  the  head.  Hence  the  specific  name  "mobilis." 
The  cervical  glands  lie  behind  the  nerve-ring,  since 
their  ducts  have  been  followed  backward  to  behind  the  nerve-ring.  There  are 
also  ducts  of  glands  to  be  seen  in  the  ventrally  submedian  sectors  of  the  oesoph- 
agus. The  pyriform  renette  cell,  which  lies  a  very  short  distance  behind  the 
base  of  the  neck,  empties  through  a  rather  distinct  ampulla  twice  as  far  back  as 
the  base  of  the  pharynx.  The  narrow  nerve-ring  is  accompanied  by  large  distinct 
nerve  cells  arranged  in  groups.  From  the  rather  large  and  conspicuous,  more  or 
less  elevated  vulva,  the  large  muscular,  non-cutinized  vagina  leads  inward  to 
the  two  straight  uteri.  The  eggs  are  twice  as  long  as  the  body  is  wide,  and  two 
and  one-half  times  as  long  as  wide.  Judging  by  their  size  when  empty,  the  uteri 
are  adapted  to  receive  one  egg  at  a  time,  possibly  two.  The  posterior  ovary  is 
a  little  the  smaller;  both  are  more  or  less  cylindroid,  finally  tapering,  of  medium 
size,  and  reach  three-fourths  the  distance  back  to  the  vulva.  The  ova  in  them 
are  arranged  single  file.  An  ovum  about  to  enter  the  oviduct  is  two  to  three 
times  as  long  as  the  body  is  wide,  and  about  one-fourth  as  wide  as  long. 

Habitat:  Sea-weed,  Squibnocket,  Martha's  Vineyard,  Mass.,  U.  S.  A.;  Bathing 
Beach,  Wood's  Hole,  Mass.,  U.  S.  A.;  not  common.  Examined  living,  in  water. 
Fig.  93. 


94.  Onchulus  longicaudatus  n.  sp.  1.6 


"1"  Cuticle  naked 


1.7         2.3  2- 

except  for  the  setae  on  the  head;  its  striae  very  difficult  of  resolution.  Whether 
the  onchium  is  hollow  and  perforated  remains  uncertain,  » 
but  seems  probable.  Neck  subcylindroid.  The  cylin- 
droid oesophagus  is  at  the  nerve-ring  three-fifths,  and 
finally  three-fourths,  as  wide  as  the  corresponding  por- 
tioh  of  the  neck.  Throughout  its  length,  the  colorless, 
coarse  musculature  is  interspersed  with  granular,  gland- 
ular  tissues,  as  in  Oncholaimus,  making  it  seem  probable 
that  the  pharyngeal  outlets  are  similar,  but  no  duct  has 
been  definitely  established  in  the  dorsal  onchium.  There 
is  a  cylindroid  cardia,  about  one-third  as  wide  as  the  oe 
base  of  the  neck.  Scattered  setae  having  a  length  equal 
to  the  breadth  of  two  annules  occur  on  the  tail.  There 
are  no  caudal  glands.  The  description  is  derived  from  a  single  young  specimen 
in  which  the  vulva  was  not  yet  developed.  The  immature  ovaries  reached  two- 
thirds  the  way  back  to  the  location  of  the  future  vulva. 

Habitat:  Soil  about  the  roots  of  living  plants  imported  from  Brazil  into  the 
United  States.     Flemming  to  glycerine  jelly.     Fig.  94. 


314  ORDER   ANAXONCHIA 

1-.  ..  .<-.«.  .1?-.  .  .'.'5.1'.'..  .»?.>2.4.. 

95.  Digitonchus  uniformis  n.  sp.     •»      l-5      1-9         *•          **5  Possibly  the 

transverse  striae  are  resolvable  into  exceedingly  minute  markings.  Cuticle 
naked  except  for  the  cephalic  setae.  Lips  three,  possibly  very  faintly  double. 
Onchium  spear-like,  solid.  Anteriorly,  the  neck  is  convex- 
conoid.  The  oesophagus  has  not  been  well  seen  but 
appears  to  bo  more  or  less  cylindroid;  its  diameter  at 
the  base  is  about  half  as  great  as  that  of  the  base  of  the 
neck.  Its  lining  is  subdistinct,  its  colorless  musculature 
fine  in  texture.  The  more  or  less  thick-walled  intestine, 
fuNe  "  x750  which  has  a  faint  lumen,  becomes  at  once  half  as  wide  as 
the  body.  Cardiac  collum  one-third  as  wide  as  the  base  of  the  neck.  From  the 
more  or  less  elevated  anus,  the  prominent,  cutinized  rqctum  is  about  as  long  as 
the  anal  body-diameter.  The  conoid,  arcuate  tail  tapers  from  the  anus  to  the 
rather  simple  spinneret.  The  rather  broadly  saccate  caudal  glands  are  packed 
behind  the  anus  in  the  anterior  third  of  the  tail;  they  empty  by  separate  ducts. 
The  lateral  fields  are  one-third  as  wide  as  the  body.  Renette  unknown.  The 
nerve-ring  is  accompanied  by  obscure  nerve  cells.  From  the  more  or  less  con- 
tinuous, inconspicuous  vulva,  the  vagina  extends  inward  three-fifths  the 
distance  across  the  body.  It  is  muscular  and  more  or  less  cutinized.  The 
medium-sized,  tapering  ovaries  reach  half  way  back  to  the  vulva. 

Habitat:  Beach  sand,  Squibnocket,  Martha's  Vineyard,  Mass.,  U.  S.  A.    Flem- 
ming  to  glycerine  jelly.     Fig.  95. 


.  . 
96.  Ypsilon  exile  n.  sp.    -1      V      %i         i6       L6  There  are 

cervical  setae  about  half  as  long  as  the  neck  is  wide.     Three  flat, 
minute,  confluent  lips  bear  a  circlet  of  six  forward-pointing  or 
somewhat  spreading  papillae  around  the  mouth  opening.     Though 
there  are  six  nerves,  one  to  each  papilla,  they  are  not  precisely 
equidistant,  but  seem  to  be  arranged  in  three,  somewhat  distinct 
pairs.     Pharynx  relatively  strongly  cutinized.     In  optical  con- 
tour, the  anterior  end  of  the  onchium  is  more  or  less  crescent- 
shaped;  this  cup-shaped  head  is  fixed  obliquely  on  the  strong, 
straight  element  that  forms  the  main  portion  of  the  dorsal  wall     x750 
of  the  pharynx.    The  head  of  the  onchium  is  yellowish  in  color.    The  neck  is 
cylindroid  posteriorly,  convex-conoid  anteriorly.     The  oesophagus,  narrow  and 
more  or  less  cephaloboid  in  form,  ends  in  a  somewhat  cylindroid  cardiac  swelling, 
two-sevenths  as  long  as  the  neck,  and  three-fifths  as  wide  as  the  base  of  the 
neck.    At  the  nerve-ring,  the  oesophagus  is  one-third,  just  in  front  of  the  cardiac 
swelling  also  one-third,  as  wide  as  the  corresponding  portion  of  the  neck.     The 
lining  of  the  oesophagus  is  rather  prominent.     The  colorless  musculature  of  the 
oesophagus  is  of  fine  texture;  in  it,  traces  of  oesophageal  glands  have  been  seen. 
There  is  a  distinct,  refractive,  cylindroid  cardia,  two-sevenths  as  wide  as  the 
base  of  the  neck.     The  intestine,  which  is  thick-walled  and  has  a  faint,  zig-zag 
lumen,  gradually  becomes  three-fourths  as  wide  as  the  body.     The  cardiac  col- 
lum is  one-third  as  wide  as  the  body.     The  anus  is  elevated,  and  the  rectum 
is  one  and  one-fourth  times  as  long  as  the  anal  body-diameter.     The  intestinal 
cells  are  packed  with  pearly  granules,  such  as  are  often  seen  in  Aphelenchus; 
the  largest  of  these  are  one-eighth  as  wide  as  the  body.    These  granules  tend  to 
be  larger  posteriorly  than  anteriorly,  and  sometimes  appear  to  be  polyhedral. 
The  posterior  part  of  the  body  tapers  from  in  front  of  the  anus,  is  at  first  conoid 
then  convex-conoid,  and  ends  in  a  spinneret  one-sixth  as  wide  as  the  base  of 


YPSILON,    GONIONCHUS  315 

the  tail.  The  ellipsoidal  to  broadly  saccate  caudal  glands  are  packed  in  a  close 
tandem  behind  and  opposite  to  the  anus  in  the  anterior  three-fifths  of  the  tail. 
Their  large,  distinct  ampullae  are  two-sevenths  as  long  as  the  tail.  There  are 
one  or  two  slender  setae  at  the  middle  of  the  tail,  and  near  the  terminus.  The 
lateral  fields  are  about  one-fourth  as  wide  as  the  body.  The  much  elongated 
renette  cell  lies  about  one  body-width  behind  the  neck.  The  frail,  strongly  arcu- 
ate, rather  slender,  tapering,  subacute  spicula  are  cephalated  by  a  constriction 
on  the  ventral  side  in  such  fashion  that  the  proximal  ends  appear  to  be  more  or 
less  barbed.  The  simple,  frail,  very  slender,  arcuate  accessory  piece  is  one-third 
as  long  as  the  spicula  and  presents  a  faint  apophysis;  its  proximal  end,  like  those 
of  the  spicula,  lies  dorsad  from  the  body-axis.  At  first  it  is  parallel  to  the  spicula, 
then  recedes  and  bends  away  at  an  angle  of  ninety  degrees.  There  are  three 
faint  and  minute  supplementary  organs  in  front  of  the  anus,  occupying  a  space 
one  and  one-half  times  as  long  as  the  body-diameter,— little  more  than  innerva- 
tions.  The  posterior  of  these  is  opposite  the  distal  ends  of  the  spicula.  The 
distance  between  the  first  and  second  is  equal  to  two-thirds,  that  between  the 
second  and  third,  to  one-half,  the  body-diameter.  At  the  posterior  end  of  the 
middle  fifth  of  the  tail  there  is  a  somewhat  raised  small  area  supplied  with  two 
subventral  nerve  endings. 

Habitat:  Coarse  sand,  Beach,  Devil's  Island,  Woods  Hole,  Mass,  U.  S.  A.  The 
sexual  organs  are  difficult  to  decipher  on  account  of  the  granules  in  the  intestine. 
It  does  not  seem  advisable  to  refer  this  species  to  Acmaeolaimus  Filipjev.  The 
following  differences  may  be  noted:  (1)  The  cuticle  is  coarsely  striated. 
(2)  The  cephalic  setae  are  in  one  circlet  only.  (3)  The  amphids  are  not  "split." 
(4)  The  pharynx  is  not  open.  (5)  The  dorsal  organ  is  "Y  "-shaped.  Possibly 
the  Filipjevian  specimen  might  have  been  referred  to  Camacolaimus  de  Man. 
Fig.  96,  p.  314. 

97.  Gonionchus  villosus  n.  sp.  Annules  separated  by  strongly  refractive  lines. 
Neck  conoid  in  the  anterior  half.  About  twice  as  far  from  the  anterior  extremity 
as  the  amphids  are  four  submedian  groups  of  hairs,  which  are  longer  than  the 
cephalic  setae.  These  groups  consist  of  three  each,  arranged  one  in  front  of  the 
other,  the  members  being  separated  by  a  distance  equal  to  the  width  of  one  of 
the  annules.  Similar  submedian  long  and  slender  hairs  occur  throughout  the 
length  of  the  body  and  are  so  numerous  as  to  con-  setqihdOJ  H)(6l 
stitute  a  very  striking  feature.  The  amphids  at 
first  appear  "O "-shaped;  in  reality,  however, 
they  are  spiral.  The  terminal  flaps  are  hinged  to 
the  lips,  and  the  anterior  portion  of  each  lip  appar- 
ently is  hinged  to  the  main  portion  of  the  wall  of  (Ufa  |jppsgj_. 00 

the  head,  which  is  itself  unusually  thin.     Onchia 

apparently  more  or  less  plate-like.    The  oesoph-  Mslficph(4)^iS£k     '    X  750 

agus  continues  to  have  the  same  diameter  until 

after  it  passes  through  the  nerve-ring;  thereafter, 

it  expands  very  little  so  that  finally  it  is  about   j.13._iq.4___24.____'_0-76_       ??•.>, J4.. 

two-thirds  as  wide  as  the  base  of  the  neck.    There    l6      *•«/«>«•«         M""'£~ 

is  a  distinct  conoid  cardia,  having  a  base  about    i..,___9.5___2_2-- .-A-". .._¥•*.>,, ,.. 

one-third  as  wide  as  the  base  of  the  neck.    The   "      ^  '"  2  J         2-4"^  2- 
intestine  becomes  at  once  about  two-thirds  as  wide  as  the  body.    It  is  rather 
thick-walled,    and    its   cross-section   would  present   about   four  to   six   cells. 
The   lining  of   the   intestine   is  refractive,  so   that  the  lumen  is  readily  fol- 
lowed; in  fact  it  is  a  rather  striking  feature.    The  cells  contain  scattered  yel- 


316  ORDER   ANAXONCHIA 

lowish  granules  of  variable  size,  arranged  irregularly.  The  posterior  lip  of  the 
anus  is  slightly  raised.  Rectum  only  about  two-thirds  as  long  as  the  anal  body- 
diameter.  The  tail  is  conoid  in  such  fashion  that,  at  a  distance  from  the  anus 
equal  to  eight  times  the  anal  body-diameter,  it  has  a  diameter  about  one-fourth 
as  great  as  at  the  anus.  The  remainder  of  the  tail  has  been  lost  from  the  speci- 
men from  which  the  description  was  drawn  and  is  therefore  of  unknown  form; 
hence  the  dimensions  given  in  the  formula  must  be  interpreted  accordingly.  The 
tail  is  just  as  distinctly  striated  as  the  body.  -The  lateral  fields  are  about  one- 
third  as  wide  as  the  body.  It  is  probable  that  the  renette  is  located  at  a  distance 
behind  the  base  of  the  neck  about  equal  to  two  body-diameters.  At  this  point 
there  is  an  elongated  structure  somewhat  longer  than  the  body  is  wide  and  about 
one-fifth  as  wide  as  it  is  long,  which  bears  a  general  resemblance  to  a  renette 
cell.  From  the  slightly  elevated  vulva,  the  vagina  extends  inward  and  forward. 
The  tapering  ovary  ends  somewhat  in  front  of  the  cardia  where  it  is  about  one- 
fourth  as  wide  as  the  corresponding  portion  of  the  neck.  The  eggs  are  about 
three  times  as  long  as  the  body  is  wide,  and  about  one-fourth  as  wide  as  long. 
There  is  a  small  posterior  rudimentary  branch  to  the  sexual  organs,  extending 
back  from  the  vulva  a  distance  equal  to  two  to  three  body-diameters.  This 
has  been  seen  to  contain  spermatozoa  and  may  function  as  a  spermatheca.  The 
presence  of  caudal  glands  remains  problematical.  Unfortunately,  also,  in  the 
case  of  the  only  male  specimen  available,  the  tail  is  broken,  but  that  portion  of 
it  remaining  is  about  two-thirds  as  long  as  the  neck.  It  tapers  a  little  more 
rapidly  at  first  than  it  does  farther  back, — in  fact,  toward  the  terminus,  it  must 
be  very  nearly  cylindroid.  It  seems  probable  that  caudal  glands  are  present, 
but  there  is  some  doubt  about  this.  There  are  no  special  supplements,  papillae 
or  setae  on  the  male.  The  long  and  slender  hairs  found  on  the  body  occur  also 
on  the  tail,  and  are  there  equally  long  and  slender  so  far  as  observed.  The 
proximal  ends  of  the  acute,  slender  spicula  present  the  peculiarity  of  being 
separated  from  the  remainder  of  the  spicula  by  straight  shafts,  having  a  length 
somewhat  greater  than  that  of  the  cephalic  portions.  The  cephalic  portion, 
together  with  this  shaft  constitutes  about  one-fourth  of  the  spiculum;  the  remain- 
ing portion  of  the  spiculum  is  uniformly  arcuate,  and  tapers  regularly  to  the  sub- 
acute  terminus.  The  proximal  ends  of  the  spicula  lie  toward  the  dorsal  side  of 
the  body.  There  are  inconspicuous  accessory  pieces  arranged  parallel  to  and 
close  by  the  spicula,  and  which  are  about  half  as  long  as  these  latter.  The  ejacu- 
latory  duct  is  one-third,  and  the  vas  deferens  about  one-half,  as  wide  as  the  body. 
Development  of  the  spermatozoa  in  the  two  testes  presents  rather  marked  con- 
trasts. From  the  blind  end  of  the  anterior  testis,  lying  near  the  base  of  the  neck, 
the  spermatozoa  develop  regularly  and  form  spermatocytes  half  as  wide  as  the 
body,  which  develop  into  spermatozoa  with  nuclei  that  stain  prominently.  The 
blind  end  of  the  posterior  testis  contains  spermatocytes  which,  for  a  short  dist- 
ance, resemble  those  already  described,  but  they  do  not  form  large  spermato- 
cytes. They  nevertheless  develop  into  spermatozoa  having  the  character  just 
described.  At  a  distance  in  front  of  the  anus  about  equal  to  the  length  of  the 
tail,  there  are  three  glands  on  each  side  of  the  body,  arranged  tandem.  These 
glands  are  accessory  to  the  male  organs.  Each  is  more  or  less  homogeneous  ante- 
riorly, and  granular  posteriorly,  the  granules  not  retaining  carmine  stain,  as  do 
the  nucleus  and  the  anterior  parts.  The  ducts  of  these  glands  lead  backward  to 
the  cloaca. 

Habitat:  Mud,  tide  pool,  near  low  tide  mark,  Portsmouth,  New  Hampshire, 
U.  S.  A.    Fig.  97,  p.  315. 


XANTHODORA  317 

98.  Xanthodora  nuda  n.  sp.  The  striae  of  the  yellow,  naked  cuticle  have  the 
appearance  of  a  series  of  hoops  that  are  considerably  wider  on  the  neck,  espe- 
cially toward  the  head.  The  anterior  half  of  the  neck  is  convex-conoid,  the 
convexity  increasing  steadily  toward  the  head.  From  the  point  where  the 

striae  cease  on  the  head,  the  cuticle  diminishes 
i'|-  •  •'"  •  -^Y  •  •  ''^V  •  •  y8->2-2»-     very  rapidly  in  thickness,  so  that  opposite  the 

dorsal  tooth,  it  is  not  more  than  one-third  as 
I'.l ' '  3*5  '  'Ts  "  "  ?j  ••>'£  9->2-  "     thick  as  a  little  farther  back;  thence  onward,  it 

is  thin  to  a  point  half  way  between  the  circlet  of 

setae  and  the  axis  of  the  mouth  opening.  At  this  point,  the  hard  cuticle  ceases 
and  there  is  a  very  minute,  faint  groove  encircling  the  lip-region.  The  lips  come 
together  so  as  to  form  a  vestibule  having  a  width  about  one-third  as  great  as  the 
diameter  of  the  circlet  of  setae.  The  tissues  of  the  lips  apparently  reach  back  a 
little  farther  than  the  apex  of  the  dorsal  tooth,  and  their  limits  are  rather  easily 
noted  on  account  of  the  fact  that  they  attract  carmine  stain  more  than  the 
surrounding  tissues  do.  The  lip-region  appears  to  be  longitudinally  striated 
internally,  and  probably  to  consist  of  about  a  dozen  elements  folded  together. 
When  the  mouth  is  open  and  the  onchium  thrust  forward,  the  labial  region  is 
seen  to  be  practically  continuous  and  entire  on  its  anterior  margin,  from  which 
it  follows  that  any  striations  appearing  when  the  mouth  is  closed  are  due  to 
foldings  of  the  lip-region.  When  the  mouth  is  open  and  the  lips  expanded,  the 
amphids  become  more  nearly  circular.  When  the  lips  are  closed,  the  vestibule 
widens  out  but  little  in  front  of  the  dorsal  tooth,  whose  apex  lies  in  the  axis  of 
the  vestibule.  The  pharynx  is  surrounded  by  muscles  which  appertain  particu- 
larly to  it,  as  is  indicated  by  the  fact  that  they  are  separated  from  the  oesoph- 
agus by  a  broad  but  fairly  distinct  constriction.  The  oesophagus  continues  to 
have  the  same  diameter  until  near  the  nerve-ring,  where  it  diminishes  somewhat 
in  diameter.  Very  soon  after  passing  through  the  nerve-ring,  it  enlarges,  some- 
times rather  suddenly,  to  form  the  elongated  posterior  three-fifths  of  the  organ. 
This  enlarged  part  averages  to  be  about 
three-fifths  as  wide  as  the  corresponding  por- 
tion of  the  neck,  and  contains  a  massive  lin- 
ing,  which,  when  viewed  in  optical  section, 
occupies  one-fifth  of  the  diameter.  This 
enlarged  portion  of  the  oesophagus  is  divided 
into  three  regions  by  breaks  in  its  radial  mus- 
culature,  of  which  one  region  comprises 
nearly  the  whole  of  the  anterior  half.  The 
other  two  parts  are  of  subequal  size.  Though 
the  lining  of  the  oesophagus  is  quite  distinct  . 
in  the  narrow  portion,  it  is  considerably  less 
so  in  the  wider  portion,  and  ceases  a  short 
distance  in  front  of  the  posterior  end  of  the  P 
oesophagus.  Cardiac  collum  less  than  one- 
third  as  wide  as  the  base  of  the  neck.  For  a  $?•• 
short  distance,  the  intestine  is  composed  of  small  cells  differing  from  those  which 
make  up  its  main  part.  These  cells  stain  more  strongly  with  carmine  and  con- 
tain nuclei  of  relatively  larger  size.  This  region  probably  may  be  regarded  as  a 
sort  of  cardia.  The  intestine  becomes  almost  at  once  two-fifths  as  wide  as  the 
body.  Its  cross-section  would  present  about  eight  cells.  The  cells  are  packed 


318  ORDER   ANAXONCHIA 

with  numerous  yellowish  granules.  In  the  body  cavity  at  the  cardiac  collura, 
there  are  three  ellipsoidal  groups  of  cells,  two  dorsally  submedian  and  one  ven- 
tral or  nearly  so.  These  groups  contain  eight  to  ten  nuclei,  and  one  of  them  is 
seen  to  be  connected  to  a  distinct,  refractive  strand,  extending  forward  along 
the  surface  of  the  oesophagus.  These  groups  of  cells  have  their  nuclei  close 
together  and  seem  to  have  a  general  membrane  covering  them.  In  addition  to 
these  groups  of  cells,  there  are  two  other  granular  bodies,  ventrally  submedian, 
each  containing  a  single,  strongly  staining  nucleus,  and  a  second  body  which 
does  not  stain  so  strongly.  The  structure  of  these  latter  is  suggestive  of  that  of 
the  ordinary  renette  cell,  but  their  connections  have  not  been  made  out.  Rec- 
tum somewhat  longer  than  the  anal  body  diameter.  The  three  caudal  glands 
are  arranged  in  a  close  tandem  in  front  of,  opposite  to  and  behind  the  anus. 
Each  is  a  large  cell  with  a  protoplasmic  network,  in  the  midst  of  which  the  single 
nucleus  is  slung.  The  lateral  fields  are  about  one  fourth  as  wide  as  the  body  and 
are  composed  of  two  ranges  of  cells  with  a  space  between  them,  in  which  lie 
nuclei  belonging  to  cells  of  a  different  group.  Renette  unknown.  From  the 
slightly  raised  anus,  the  arcuate  tail  is  conoid  to  the  terminus,  which  has  a 
diameter  about  one  third  to  one  half  as  great  as  that  of  the  base  of  the  tail. 
From  the  very  slightly  elevated  vulva,  the  well  cutinized  vagina  extends  fully 
half  way  across  the  body.  The  ovaries  reach  half  way  back  to  the  vulva  and 
contain  ten  to  fifteen  ova  arranged,  for  the  most  part,  single  file.  The  moder- 
ately thin-shelled  eggs  are  twice  as  long  as  the  body  is  wide  and  one-third  as 
wide  as  long.  They  occur  in  the  uteri  one  at  a  time.  The  spermatozoa  in  the 
uterus  are  one-seventh  as  wide  as  the  body.  The  conoid,  arcuate  tail  of  the 
male  begins  to  taper  from  a  short  distance  in  front  of  the  anus.  The  six  sup- 
plementary organs  occupy  a  distance  equal  to  the  length  of  the  tail.  The  pos- 
terior supplement  is  nearly  opposite  the  posterior  thirds  of  the  spicula;  the 
second,  third  and  fourth  succeed  each  other  without  intervening  spaces,  in 
such  a  way  that  the  third  and  fourth  are  pretty  nearly  opposite  the  proximal 
ends  of  the  spicula.  The  fifth  is  separated  by  a  greater  space  from  the  fourth, 
and  the  sixth  is  about  as  far  from  the  fifth  as  the  fifth  is  from  the  fourth.  The 
fifth  and  sixth  are  of  smaller  size  than  the  others,  the  inconspicuous  sixth  being 
the  smallest  of  all.  Their  apices  are  more  transparent  than  the  other  portions. 
An  unusual  feature  is  the  presence  of  nerve  endings  between  the  organs.  It 
is  possible  that  nearer  the  anus  still  than  any  described,  there  is  another  incon- 
spicuous organ  of  somewhat  the  same  character.  The  strongly  arcuate,  some- 
what acute,  yellowish  spicula  are  about  twice  as  long  as  the  anal  body-diam- 
eter. They  appear  to  be  widest  in  the  middle  and  to  taper  both  ways.  The 
cephalated  portion  of  the  spicula  are  cut  off  obliquely.  The  proximal  ends  lie 
a  little  to  the  dorsal  side  of  the  body-axis.  The  accessory  pieces  are  for  the 
main  portion  of  their  length  not  very  conspicuous.  Surrounding  the  distal 
ends  of  the  spicula,  however,  there  is  a  rather  prominent  portion  which  must 
be  reckoned  a  portion  of  the  accessory  apparatus.  Oblique  copulatory  mus- 
cles are  present  for  a  distance  twice  as  great  as  the  space  occupied  by  the  sup- 
plementary organs.  The  ejaculatory  duct  is  about  one-third,  and  the  vas 
deferens  a  little  more  than  one-third,  as  wide  as  the  body.  It  remains  uncer- 
tain whether  there  is  one  testis  or  two,  but  the  evidence  seems  to  favor  the 
supposition  that  there  is  one  only,  and  that  its  blind  end  lies  about  as  far  behind 
the  base  of  the  neck  as  the  nerve-ring  is  in  front  of  it. 
Habitat:  Larat,  East  Indies.  Marine.  Fig.  98,  p.  317. 


ANAXONCHIUM,    BOLBOLAIMUS 


319 


1.6       7.6±17.1  .    .    .'*.    .    .  90..  ?11.. 

99.  Anaxonchiwn  liiorium  n.  sp.  Li  '  Vi-'  2.3  '  '  2.47^*1.9  '  Cuticle  thin, 
but  considerably  thicker  near  the  head.  Striae  resolvable  with  difficulty  into 
dot-like  elements,  which  are  close  together  on  the  body,  more  distant  on  the 
head.  The  striae  are  altered  on  the  lateral  fields  so  as  to  give  rise  to  a  ladder-like 
pattern,  with  the  "rungs"  very  close  together.  Cephalic  setae  two-jointed.  No 
pores  are  seen  in  the  cuticle;  nevertheless,  they  may  have  been  present  and  escaped 
notice.  The  lips  are  thick  and  double.  In  the  single  male  specimen  examined, 
the  conical  branches  of  the  lips  end  in  minute  setae,  each  about  as  long  as  the 
labial  setae,  and  terminating  in  a  "blob, " — this  latter  hardly  an  artefact.  Dor- 
sal onchium  opposed  on  the  ventral  side  by  several  irregularly  arranged,  small 
denticles,  among  which  probably  two  submedian  ones  dominate.  Apparently 


somewhat  similar  denticles  occur 


setlb(6) 


trm 


behind  and  above  the  dorsal 
onchium.  Amphids  peculiar,  large, 
faint.  The  plain  oesophagus,  near  on 
the  nerve-ring  is  one-half,  and  fin- 
ally three-fourths,  as  wide  as  the 
corresponding  portion  of  the  neck. 
Its  lining  appears  corrugated;  its 
colorless  musculature  is  more  or  less 
coarse,  but  there  seem  to  be  no  indi- 
cations of  the  presence  of  glands, 
and  there  is  no  distinct  cardia.  The 
thin-walled  intestine,  which  has  a 
rather  faint,  though  distinctly  visi- 
ble lumen,  becomes  at  once  half  as  *750 
wide  as  the  body,  and  in  cross-section  would  present  four  to  six  cells.  Cardiac 
collum  one-half  as  wide  as  the  neck.  The  cells  of  the  intestine  contain  scattered 
yellow  granules  of  variable  size,  having  a  diameter  about  equal  to  the  width  of 
two  annules  of  the  cuticle.  The  tail  tapers  from  the  anus,  and  is  at  first  conoid 
then  cylindroid  in  the  posterior  third,  where  it  is  about  one-fourth  as  wide  as  at 
the  anus.  A  few,  rather  small,  tapering,  subacute  setae  occur  on  the  tail.  The 
lateral  fields  are  about  one- third  as  wide  as  the  body.  The  non-granular  ellip- 
soidal renette  cell  lies  only  a  short  distance  behind  the  neck,  and  is  three-fourths 
as  long  as  the  body  is  wide,  and  one-third  as  wide  as  long.  The  rather  pronounced 
clavate  ampulla  empties  through  the  distinct  pore  lying  close  to  its  anterior  end. 
The  nerve-ring  is  accompanied  by  obscure  nerve  cells.  The  yellowish  spicula 
are  guided  by  two  separate,  strong,  rather  wide,  more  or  less  arcuate,  somewhat 
shoe-shaped  pieces  near  the  anus,  with  a  single  median  piece  between  and  behind 
them.  Ejaculatory  duct  one-fourth,  testis  two-thirds,  as  wide  as  the  correspond- 
ing portion  of  the  body. 

Habitat:  Marine;  Belmar,  N.  J.,  U.  S.  A.,  below  low  tide  mark  in  beach  sand. 
Female  unknown.  Anaxonchium  bears  considerable  resemblance  to  Cyatho- 
laimus,  but  differs,  among  other  ways,  in  the  almost  obsolete  amphid  (?),  the 
reflexed  testis,  and  in  the  large  number  of  small  supplementary  organs.  Fig.  99. 

lOOa.  Bolbolaimus  pellucidus  n.  sp.  Type  species.  Naked  except  for  the  setae 
on  the  head;  possibly  there  are  very  inconspicuous  wings.  Lips  subdistinct,  the 
region  elastic  and  finely  subdivided.  Margin  of  the  lip-region  serrated  by  the 
forward  projection  of  about  fifteen  papillae  (?)  with  minute  bristles  outside  the 
serrations.  The  appearance  is  as  if  each  papilla  is  armed  with  a  pair  of  minute 


320  ORDER   ANAXONCHTA 

bristles  very  difficult  to  see.  Onchium  capable  of  being  protruded  past  the  lips. 
Opposite  the  onchium  is  a  pseudo-onchium,  somewhat  smaller,  and  more  dis- 
tinctly visible  in  some  attitudes  of  the  pharynx  than  in  others.  Amphids  exceed- 
ingly inconspicuous,  nearly  circular,  a  little  the  wider  transversely,  apparently 
circular  but  really  consisting  of  spirals  of  one  wind  slightly  open  behind.  At 
the  nerve-ring,  the  oesophagus  is  three-fifths,  just  in  front  of  the  cardiac  bulb 
one-half,  and  finally  five-sixths,  as  wide  as  the  base  of  the  neck.  This  latter 
measurement  is  that  of  the  elongated,  ellipsoidal  cardiac  bulb.  The  rather 
prominent,  apparently  corrugated  lining  of  the  oesophagus  is  distinctly  visible. 

sefMfSfi.9      6.6     u.9      -46.6-     ,  The    musculature 

>  1.2,,  becomes   coarse  near 

the  cardiac  bulb. 

7.2     M.7       "-M       91.6  ^ ^  ^     There  is  a  transverse 
z.4/     2^s_ .       2.5  -fNM  division  of  the  muscu- 

lature of  the  .cardiac  bulb  near  the  middle.  The 
wall  of  the  intestine  is  of  variable  thickness;  the 
lumen  is  distinct.  Gradually  the  intestine  becomes 
two-thirds  to  three-fourths  as  wide  as  the  body ;  its 
spa  ^rncoe^  nd'.  * 750  cross-section  would  present  five  to  six  cells.  Often 

the  lumen  of  the  intestine  presents  the  appearance  of  having  certain  cells  bulging 
inward.  Cardiac  collum  one-sixth  as  wide  as  the  neck.  From  the  more  or 
less  elevated  anus,  the  cutinized  rectum  extends  inward  for  a  distance  five- 
sixths  as  great  as  the  body-diameter.  From  the  anus,  the  tail  is  conoid  to  the 
rather  blunt  terminus.  The  long,  simple  spinneret  is  in  its  basal  part  one- 
third  as  wide  as  the  base  of  the  tail.  The  broadly  saccate  caudal  glands  form 
a  loose  tandem  behind  the  anus  in  the  anterior  half  of  the  tail;  they  empty 
through  separate  ducts  and  ampullae,  the  latter  elongated.  The  lateral  fields 
are  one-third  to  two-fifths  as  wide  as  the  body.  The  ellipsoidal,  non-granular 
renette  cell  lies  close  behind  the  neck,  and  is  two-thirds  as  long  as  the  body 
is  wide  and  two-thirds  as  wide  as  long.  The  ampulla  is  one-third  as  long  as 
the  neck  is  wide,  and  three-fourths  as  wide  as  long.  The  nerve-ring  is  accom- 
panied by  obscure  nerve  cells.  From  the  small,  inconspicuous,  rather  contin- 
uous vulva,  the  small  tubular  vagina  extends  inward  one-third  the  distance  across 
the  body.  Its  inner  wall  is  cutinized,  so  that  its  rectangular  furcation  is  plainly 
to  be  seen.  The  ellipsoidal  eggs  are  one  and  one-half  times  as  long  as  the  body 
is  wide  and  appear  to  begin  segmentation  before  being  deposited.  One  or  two 
at  a  time  occur  in  the  uteri,  which  are  five  times  as  long  as  the  body  is  wide. 
The  somewhat  narrow,  tapering  ovaries  contain  about  a  dozen  ova  arranged 
single  file  for  the  most  part,  but  irregularly  near  the  blind  end.  The  faint, 
acute,  tapering,  stoutish  spicula  are  colorless  and  one  and  one-half  times  as  long 
as  the  anal  body-diameter.  They  are  so  located  that  their  proximal  ends  appear 
to  be  opposite  the  body-axis.  The  simple,  strong,  separate  accessory  pieces 
are  somewhat  slender.  They  are  yellow  and  quite  as  conspicuous  as  the  spic- 
ula. Their  applied  parts  are  two-thirds  as  long  as  the  spicula,  from  which  they 
recede  a  little.  Their  proximal  ends  appear  to  lie  dorsad  from  the  body-axis. 
The  six,  very  small  and  inconspicuous,  equidistant  supplementary  organs  occupy 
a  distance  somewhat  less  than  the  length  of  the  tail.  The  last  is  opposite  the 
proximal  parts  of  the  spicula.  The  spaces  between  them  are  about  equal  to 
half  the  body-diameter.  They  hardly  disturb  the  ventral  contour  of  the  body. 
Possibly  there  is  also  one  near  the  anus.  They  are  papilloid  and  have  but  slight 
elevation.  The  ejaculatory  duct  is  one-half,  the  vas  deferens  one-half,  and 


BOLBOLAIMUS,   ACANTHONCHUS  321 

the  testes  two-thirds,  as  wide  as  the  corresponding  portion  of  the  body,  but  the 
testes  taper  so  that  at  their  blind  ends  they  are  only  one-half  as  wide  as  the  body. 
The  various  regions  of  the  male  sexual  organs  are  separated  from  each  other  by 
narrower  channels.  After  synapsis,  the  spermatozoa  grow  and  become  granular. 
Habitat:  Sand,  below  low  tide  mark,  Belmar,  N.  J.,  U.  S.  A.  Sublimate  to 
balsam.  Fig.  lOOa,  p..  320. 

b.  Bolbolaimus  punctatus  n.  sp.  r6~~~2."8/"";~lT~ j~3  XJ*1*"  Striae  resolvable 
into  rows  of  dots,  of  which  about  every  third  row  is  a  trifle  coarser,  thus  indi- 
cating the  real  width  of  the  annules.  Labial  papillae  six,  setose,  about  one-third 
as  long  as  the  cephalic  setae.  Around  the  mouth,  there  are  fine,  longitudinal 
striations  due  to  foldings  in  the  vestibule.  The  punctate  walls  of  the  pharynx 
are  well-cutinized.  There  are  two  very  small  ventrally  submedian  projecting 
onchia  opposite  the  dorsal  onchium.  The  oesophagus  near  the  nerve-ring  is 
two-fifths,  just  in  front  of  the  cardiac  bulb  a  little  more  than  two-fifths,  and 
finally  three-fourths,  as  wide  as  the  base  of  the  neck.  This  latter  measurement 
is  the  diameter  of  the  somewhat  elongated  cardiac  bulb,  which  is  two-sevenths 
as  long  as  the  neck.  There  is  an  obscure,  elongated,  two-parted  valve  in  the  car- 
diac swelling,  one-third  as  wide  as  the  swelling  m>[ 
itself.  The  cardiac  valve  is  divided  into  three 
parts,  corresponding  to  breaks  in  the  muscula-  on  SU/ml 
ture,  the  anterior  part  inconspicuous,  the  other 
two  each  occupying  nearly  one-half  the  length  n 
of  the  bulb.  The  thick-walled  intestine  becomes 
at  once  three-fifths  as  wide  as  the  body.  Its  ^ 
cross-section  would  present  three  to  four  cells, 
containing  scattered  granules  of  variable  size,  / 
the  largest  of  which  are  about  one-twenty-fifth 
as  wide  as  the  body.  Cardiac  collum  one-fourth 
as  wide  as  the  base  of  the  neck.  From  the  con-  $ 
tinuous,  inconspicuous  anus,  the  rectum  extends  inward  a  distance  two-thirds 
as  great  as  the  anal  body-diameter.  The  conoid  tail  tapers  from  the  anus  to  the 
blunt,  conoid,  symmetrical,  unarmed  spinneret.  The  broadly  saccate  caudal 
glands  lie  behind  and  opposite  the  anus  in  the  anterior  half  of  the  tail.  Meas- 
ured near  the  neck,  the  lateral  fields  are  one-fourth  as  wide  'as  the  body. 
The  ellipsoidal,  non-granular  renette  cell,  one  body-width  behind  the  neck,  is 
one-half  as  long  as  the  body  is  wide  and  five-sixths  as  wide  as  long.  From  the 
small,  inconspicuous,  continuous  vulva,  the  rather  weak  vagina  extends  inward 
two-fifths  the  distance  across  the  body.  The  elongated  eggs  are  as  long  as  the 
body  is  wide  and  three-fourths  as  wide  as  long,  and  are  packed  three  to  five  in 
each  uterus  at  once.  The  tapering  ovaries  contain  about  twenty  ova  arranged 
single  file. 

Habitat:  Marine  sand,  Nobsca  Beach,  Woods  Hole,  Mass.,  U.  S.  A.  Flemming 
to  glycerine  jelly.  Fig.  1006. 

101.  Acanthonchus  viviparus  n.  sp.  There  are  distinct  wings,  whose  presence 
is  indicated  by  about  four  to  six  longitudinal  striations,  resolvable,  at  least  the 
outer  ones,  into  rows  of  dots.  The  wings  extend  from  near  the  head  to  near 
the  tail.  Neck  conoid.  Setae  two-  (or  three-)  jointed.  The  lip-region  appears 
to  be  divided  into  twelve  parts,  or  into  six  parts,  each  of  which  is  double.  The 
mouth  cavity  is  cyathiform  and  shallow  when  the  lips  are  closed  and  is  entered 


322  ORDER   ANAXONCHIA 

through  a  narrow  vestibule.  The  cavity  itself  is  very  small,  and  a  good  deal 
wider  than  it  is  high  when  the  lips  are  closed.  In  fact,  when  the  lips  are  closed 
they  appear  to  form  a  depression  on  the  front  of  the  head,  so  that  their  interior 
margins  actually  rest  on  the  dorsal  tooth  and  on  the  base  of  the  pharynx.  The 
pharynx  actually  continues  to  twice  the  depth  indicated  in  the  formula,  though 
when  the  mouth  is  closed  this  posterior  portion  appears  to  be  very  similar  to 
the  lumen  of  the  oesophagus.  The  oesophagus  swells  a  little  in  the  anterior 
third,  then  diminishes  almost  imperceptibly,  and  finally  swells  toward  the  pos- 
terior extremity  where  it  is  two-thirds  as  wide  as  the  base  of  the  neck.  The 
thick-walled  intestine  becomes  at  once  two-thirds  as  wide  as  the  body,  and 
expands  so  as  soon  to  be  three-fourths  to  four-fifths  as  wide  as  the  body.  Its 
cross-section  would  probably  present  about  eight  cells.  The  elongated  ventral 

7.4+  15.      "W"      92.3  >16      gland  lies   im- 

'%J '*"'•' i;i 2'6'    '  "  mediately  be- 

8.1.^15.        "-M         91.9  y. ,      hind  the  cardiac 

'&'*"* W^iV     '  -    constriction. 

The  lateral  fields  are  about  one-third  as  wide 
as  the  body,  and  are  composed  mainly  of  a 
double  row  of  very  prominent  ellipsoidal  cells, 
which  in  the  females  at  least,  may  be  most 
clearly  seen  in  the  region  of  the  neck.  From 
X750  the  slightly  raised  vulva,  the  vagina  leads 
inward  about  half  way  across  the  body.  The  uteri  are  generally  about  one  and 
one-half  times  as  long  as  the  neck,  and  contain  numerous  developing  eggs  or 
embryos.  The  ovaries  are  reflexed  for  a  distance  about  twice  as  great  as  the 
body-diameter,  and  contain  a  dozen  or  more  ova  arranged  in  several  series.  This 
species  is  viviparous.  Tail  of  the  male  is  very  much  like  that  of  the  female,  but 
more  arcuate.  Its  terminus  has  a  diameter  one-fifth  as  great  as  the  diameter 
of  the  base  of  the  tail.  The  equidistant  supplements  are  of  unequal  size,  those 
more  distant  from  the  anus  being  much  the  larger.  The  first  is  opposite  the  prox- 
imal ends  of  the  spicula  and  is  very  minute.  It  is  visible  mainly  on  account  of 
the  refractive  nature  of  the  material  of  which  it  is  composed.  The  second  is 
about  twice  as  far  from  the  anus  as  the  first  and  of  about  the  same  size.  The 
third,  which  is  three  times  as  far  from  the  anus  as  the  first,  is  very  much  larger, 
having  a  length  half  as  great  as  the  body-diameter;  its  internal  walls  are  brown 
and  strongly  lined  and  refractive.  It  is  somewhat  curved  and  passes  inward 
and  forward;  its  proximal  portion  is  slightly  cephalated.  The  fourth  of  these 
organs  is  more  than  four  times  as  far  from  the  anus  as  the  first,  and  is  more  than 
twice  as  long  as  the  third,  having  a  length  approximately  equal  to  the  body- 
diameter.  Its  internal  walls  are  strongly  cutinized,  and  it  is  a  very  prominent 
feature,  almost  as  much  so  as  the  spicula.  Where  it  passes  through  the  cuticle, 
its  point  is  curved  backward;  thence  inward,  it  is  somewhat  sigmoid,  enlarging 
all  the  time,  so  that  its  proximal  portion  is  about  one-fifth  as  wide  as  the  cor- 
responding portion  of  the  body.  The  slightly  arcuate,  rather  uniform  spicula 
are  somewhat  longer  than  the  anal  body-diameter.  Their  proximal  ends  are  not 
distinctly  cephalated.  Parallel  to  the  spicula,  and  extending  inward  from  the 
prominently  raised  anus  for  a  distance  three-fourths  the  length  of  the  spicula, 
are  the  accessory  pieces,  whose  distal  extremities  are  two  to  three  times  as  wide 
as  the  spicula,  but  which  decrease  in  size  internally.  They  are  considerably 
more  prominent  than  the  spicula.  The  ejaculatory  duct  is  about  half  as  wide 
as  the  body. 


ACANTHONCHUS,    XENONEMA  323 

Habitat:  Marine  mud,  San  Pedro,  California.     Possibly  another  species  exists 
at  Woods  Hole,  Mass.,  U.  S.  A.    Sublimate  to  balsam.    Fig.  101,  p.  322. 

-1jl--!--6-t_1?-A___l6?l ®-5  >  .95  .. 

102.  Xenonema  obesum  n.  &p.  \I~(.>2-9~VM  "  7.T"  T.  "  Striae  resolvable 
with  high  powers  into  rows  of  dots  or  elongated  markings  which  are  altered  some- 
what on  the  lateral  field,  where  there  is  a  wing  extending  from  near  the  base  of 
the  neck  to  the  base  of  the  tail.  There  are  setae  on  all  parts  of  the  body,  but 
they  do  not  appear  to  be  very  numerous.  Pharynx  apparently  consisting  of  a 
cavity  whose  walls  are  folded  and  which  is  capable  of  being  opened  outward. 
The  oesophagus  continues  to  have  the  same  diameter  until  near  the  posterior 
end,  where  it  contracts  slightly  and  then  expands  to  form  the  pyriform  cardiac 
bulb,  four-fifths  to  five-sixths  as  wide  as  the  base  of  the  neck.  There  is  no  car- 
dia.  The  intestine  at  first  is  only  one-fourth  as  wide  as  the  oesophageal  bulb. 
Its  cross-section  presents  about  four  or  five  cells;  that  those  next  the  oesophagus 
are  physiologically  different  from  those  following  is  shown  by  the  way  in  which 
they  stain.  The  intestine  soon  enlarges  so  that  its  maximum  diameter  is  twice 
as  great  as  that  presented  near  the  bulb,  but  nowhere  does  the  intestine  become 
more  than  about  half  as  wide  as  the  body.  Its  cells  contain  a  few  yellowish  or 
brownish  granules  of  variable  size,  the  largest  of  which  have  a  diameter  about 
equal  to  the  distance  between  two  striae  of  the  cuticle,  the  smallest  being  not 
more  than  one-tenth  as  wide;  otherwise,  the  cells  of  the  intestine  are  very  trans- 
parent so  that  their  nuclei  can  readily  be  seen.  These  latter  are  of  large  size 
and  each  presents  a  distinct  nucleolus;  the  average  diameter  of  one  of  these  nuclei 
is  rather  more  than  double  the  distance  between  two  successive  striations.  The 
anus  is  elevated;  the  rectum  is  two  and  one-half  to  three  times  as  long  as  the  anal 
body-diameter.  Immediately  behind  the  anus,  the  tail  diminishes  abruptly  in 
diameter,  and  in  this  region  for  a  short  distance  near  the  anus  on  the  ventral  sur- 
face, the  striations  of  the  cuticle  are  much  less  conspicuous.  The  location  of 
the  excretory  pore  and  the  ventral  gland  remains  uncertain,  but  it  appears  pos- 
sible that  the  latter  lies  a  short  distance  in  front  of  the  cardiac  bulb.  The 
lateral  fields  are  about  one-fourth  as  wide  as  the  body,  corresponding  approxi- 
mately in  width,  at  least  in  the  anterior  part  of  the  body,  with  the  alterations 
in  the  transverse  striae  which  exist  along  the  sides  of  the  body.  The  tail  is 
conical  from  a  short  distance  behind  the  anus.  Behind  ^  ^m^^  (imph 
the  anus,  the  tail  diminishes  so  rapidly  in  diameter,  espe- 
cially  on  the  ventral  side,  that  it  becomes  almost  at  once  ™— 
only  about  two-thirds  as  wide  as  at  the  anus;  thence  am. 
onward,  it  is  conical.  The  three  caudal  glands  are  located 

in  a  tandem  series  in  front  of  the  anus.     From  the  enor-  ^ 

mously  developed  vulva,  the  vagina  leads  inward  and  forward  at  an  angle  of 
forty-five  degrees  with  the  body-axis  a  distance  equal  to  the  span  of  eight  to 
ten  striae.  The  walls  of  the  vagina  are  brownish,  thick,  and  highly  refractive. 
There  is  a  single  uterus  connected  with  two  short  ovaries,  each  containing  three 
to  four  ova.  This  entire  system  of  organs  is  clustered  near  the  vulva  and  occu- 
pies a  distance  about  five  times  as  great  as  the  average  body-diameter.  The 
size  and  nature  of  the  eggs  remains  to  be  discovered.  Overhanging  the  vulva  is 
a  flap-like  expansion  of  the  cuticle  which  adds  much  to  the  ventral  prominence. 
Tissues  of  the  body-wall  are  contained  also  in  the  cavity  of  this  peculiar  expan- 
sion of  the  cuticle.  Owing  to  the  peculiar  development  in  this  region,  the 
diameter  of  the  body  here  is  more  than  twice  the  average  body-diameter.  In  fact 


324  ORDER   ANAXONCHIA 

these  structures  are  so  very  peculiar  as  to  suggest  abnormality,  but  as  there  is 
no  evidence  of  any  disease  or  malformation  in   the  single,  very  transparent 
specimen  examined,  it  seems  best  to  regard  it  as  the  normal  form  of  a  very 
exceptional  species. 
Habitat:  Salt  River,  Jamaica,  in  six  inches  of  water.     Fig.  102,  p.  323. 

1.8        10.          16.                Y  88. 
......... .^  .g  „ 

103.  Amphispira  rotundicephala  n.  sp.  *•        •*•?      1i?         •*•?       5-  Contour 
plain,  or  exceedingly  finely  crenate.     Apparently  there  are  very  faint  subce- 
phalic  setae  near  the  base  of  the  "cuirasse."     At  the  mouth  opening  of  the  single 
specimen  examined  there  are  three  punctate  spherical  elements,  as  shown  in  the 
illustration.     The  significance  of  these  remains  problematical;  while  they  may 
possibly  be  fixation  products,  such  a  supposition  is  doubtful.     Neck  conoid. 
The  oesophagus  retains  the  same  diameter  until  it  expands  to  form  the  flattish- 
pyriform  cardiac  bulb,  which  has  a  faint  valve  one-third  as  wide  as  itself.     There 
appears  to  be  an  almost  imperceptible  break  in  the  musculature  near  the  middle 
of  the  oesophagus,  and  a  corresponding  very  slight  swelling.     The  thick-walled 
intestine  has  a  faint  lumen  and  soon  becomes  one-half  as  wide  as  the  correspond- 

jj  ing  portion  of  the  body.  Its  cross-section  pre- 
sents few  cells.  From  the  apparently  contin- 
uous anus  the  prominent  rectum  extends  a 
«  distance  equal  to  the  anal  body-diameter.  The 
scattered  to  rather  numerous,  spherical  gran- 
™  ules  found  in  the  cells  of  the  intestine  are  of 
variable  size,  the  largest  being  one-thirty- 
sixth  as  wide  as  the  body.  Tail  arcuate,  co- 
X  750  noid,  ending  in  a  spinneret  one-third  as  wide  as 
its  base.  The  broadly  truncate  caudal  glands  are  located  opposite  to  and  behind 
the  anus  in  the  anterior  third  of  the  tail.  The  lateral  fields  are  one-third  as 
wide  as  the  body.  What  appears  to  be  the  renette  cell  is  located  about  three 
body-widths  behind  the  neck;  it  is  one-third  as  long  as  the  body  is  wide  and  one- 
half  as  wide  as  long.  The  location  of  the  excretory  pore  remains  unknown. 
Nerve-ring  oblique.  From  the  location  of  the  rudimentary  sexual  organs  in  the 
single  young  specimen  seen  it  seems  probable  that  they  will  develop  to  be  double 
and  symmetrically  reflexed. 

Habitat:  Soil,  Arlington  Farm,  opposite  the  District  of  Columbia,  U.  S.  A. 
Flemming  to  glycerine  jelly.  This  species  almost  seems  out  of  place  in  the 
habitat  in  which  it  was  discovered,  as  it  is  most  closely  related  to  marine  forms. 
.Fig.  103. 

104.  Micromicron  cephalatum  n.  sp.    2-8      3-7      %7         3.8  '">  V«    '  "  Neck  short, 
cylindroid.     There  seems  little  doubt  that  the  mouth  cavity  is  armed  with  a 
single,  dorsal  tooth,  which  can  be  placed  so  closely  against  the  dorsal  wall  of  the 
pharynx  as  to  be  difficult  of  detection,  although  the  tooth  itself  is  of  considerable 
magnitude.     It  appears  to  have  an  acute  apex,  located  opposite  to  or  a  little 
behind  the  labial  constriction.     Oesophagus  cylindroid,  ending  behind  in  a  pro- 
late or  pyriform  cardiac  bulb  four-fifths  as  wide  as  the  base  of  the  neck.     Cardia 
faint.     The  intestine,  which  joins  the  middle  of  the  posterior  surface  of  the 
cardiac  bulb,  is  at  first  about  one-third  as  wide  as  the  neck.     It  widens  out  grad- 
ually so  as  to  become  about  half  as  wide  as  the  body,  and  its  cross-section  would 
appear  to  be  composed  of  about  six  to  eight  cells  containing  yellowish  granules 
of  rather  uniform  size.     The  lateral  fields  are  about  one-fourth  as  wide  as  the 


MICROMICRON,    MESODORUS  325 

body.  Just  behind  the  base  of  the  neck,  there  are  cells  which  stain  a  little  more 
strongly  than  the  adjacent  structures,— possibly  renette  cells.  The  tail  of  the 
male  is  conoid  to  the  terminus,  where  it  has  a  width  one-fourth  as  great  as  at 
its  base.  The  caudal  glands  seem  to  be  located  in  the  base-of  the  tail.  The  pres- 
ence of  a  series  of  ventral  supplementary  organs  is  indicated  by  corrugations 
occurring  in  the  cuticle  on  the  ventral  surface  when  the  posterior  extremity  is 
incurved.  This  series  extends  from  the  anus  forward  a  distance  about  equal 
to  twice  the  length  of  the  tail,  and  must  be  composed  of  about 
twenty  elements.  Each  probably  consists  of  an  inconspicuous 
modification  of  the  ordinary  cuticle,  in  the  midst  of  which  there 
is  a  nerve  ending.  In  front  of  the  anus  on  the  ventrally  sub- 
median  lines  there  are  series  of  setae,  each  seta  being  nearly  one- 
third  as  long  as  the  body  is  wide.  There  is  one  of  these  setae 
in  front  of  the  anus  on  each  side,  a  second  pair  nearly  opposite 
the  proximal  ends  of  the  spicula,  and  so  on.  Similar  setae  occur  on  the  anterior 
two-thirds  of  the  tail  on  the  submedian  lines.  When  seen  in  profile,  the  spicula 
appear  at  the  middle  to  be  about  one-third  as  wide  as  the  body.  They  taper 
rapidly  to  the  acute  distal  extremities.  The  proximal  ends  are  slightly  arcuate 
in  a  ventral  direction.  Near  the  proximal  extremities  there  is  a  break  in  the 
framework  on  the  ventral  side.  The  framework  of  the  spicula  is  rather  frail, 
considering  the  size  of  the  spicula  themselves.  Muscular  fibers  appear  to  pass 
from  the  inner  free  end  of  the  accessory  piece  backward  to  the  ventral  surface 
of  the  anterior  portion  of  the  tail. 

Habitat:  Punta  Arenas,  Pacific  Coast  of  Costa  Rica.     The  intestine  contained 
a  considerable  number  of  diatoms.     Sublimate  to  balsam.     Fig.  104. 


105.  Mesodorus  cylindricollis  n.  sp.  ^  ]-7  ^  1.9^1.7  '"  Naked  cuticle 
traversed  by  exceedingly  fine,  plain  transverse  striae.  Neck  cylindroid.  In 
certain  aspects,  the  amphids  appear  to  consist  of  one  circlet  within  another, 
but  are  in  reality  true  spirals.  No  doubt  the  papillae  surrounding  the  mouth 
opening  correspond  with  folds  in  the  lip-region;  these,  however,  are  so  very  mi- 
nute as  to  be  difficult  of  resolution.  From  the  base  of  the  onchium  backward,  the 
pharynx  is  narrow  and  tapering,  and  joins  the  lumen  of  the  oesophagus  in  an 
indefinite  way  at  a  point  distant  from  the  anterior  extremity  nearly  equal  to  the 
diameter  of  the  front  of  the  head.  From  behind  the  pharyngeal  swelling,  the 
oesophagus  continues  with  about  the  same  diameter  until  it  expands  to  form  the 
rather  obscurely  pyriform  cardiac  bulb,  which  is  fully  three-fourths  as  wide  as 
the  base  of  the  neck,  and  contains  a  relatively  large  s^cph(14)  Mj^  se(J6f6) 
though  rather  simple  valvular  apparatus,  having  a  diam- 
eter half  as  great  as  that  of  the  bulb  itself.  This  valve 

is  about  twice  as  long  as  wide.     The  relatively  narrow         .  ^     ( 

intestine  joins  the  middle  of  the  posterior  surface  of  the  M  fljJaHBH^1  ~  'j m^ 
cardiac  bulb  and  soon  enlarges  so  as  to  be  two-fifths  as  _^ 

wide  as  the  body.     There  is  no  distinct  cardia.     In  cross-  Sftwcph     *750  9" 

section,  the  intestine  presents  six  to  eight  cells.  The  lateral  fields  are  about 
one-fourth  as  wide  as  the  body.  Nothing  is  known  concerning  the  renette  or 
the  excretory  pore.  The  nerve-ring  surrounds  the  oesophagus  squarely.  The 
tail  of  the  male  is  strongly  arcuate  and  conoid  from  the  prominently  raised  anus. 
The  terminus  is  blunt  and  bears  a  simple  spinneret.  The  caudal  glands  are 
packed  together  in  the  anterior  third  of  the  tail,  extending  a  little  in  front  of  the 


ORDER   ANAXOXCHIA 


anus.  The  twenty-five  supplements  are  rather  simple  and  when  the  body  is 
curved,  take  on  the  form  of  semi-cylindroid,  transverse  elevations,  the  distance 
between  them  increasing  anteriorly.  There  are  two  opposite  the  spicula  and  a 
third  a  short  distance  in  front  of  the  proximal  ends  of  the  spicula;  and  then  for 
a  distance  equal  to  four  times  the  length  of  the  tail,  the  organs  are  separated  by 
spaces  not  greater  than  their  own  width.  Thence  forward,  the  organs  are  sepa- 
rated by  wider  spaces,  and  occasionally  one  of  the  series  appears  to  be  missing. 
The  two  anterior  ones  are  separated  by  a  distance  about  twice  as  great  as  the 
width  of  one  of  the  organs.  The  entire  series  occupies  a  distance  about  eight 
times  as  long  as  the  tail.  No  special  papillae  or  setae  have  been  seen  on  the 
tail  end,  either  in  front  of  the  anus  or  behind  it.  The  proximal  ends  of  the  strongly 
arcuate,  slender-looking  spicula  appear  to  lie  nearly  opposite  the  body-axis. 
Apparently  connecting  the  cephalic  expansions  with  the  anus  are  slightly  curved, 
refractive  lines,  indicating  that  the  spicula  may  be  broader  than  would  appear 
from  an  examination  of  only  the  more  striking  portions  of  the  framework.  Acces- 
sories parallel  to,  and  two-fifths  as  long  as  the  spicula.  Ejaculatory  duct  one- 
third  as  wide  as  the  body.  The  blind  end  of  the  testis  is  about  half  as  wide  as 
the  body. 

Habitat:  Mud,  tide  pool,  Portsmouth,  N.  H.,  U.  S.  A.,  near  low  tide  mark. 
This  genus  resembles  Onyx.  Fig.  105,  p.  325. 

106.  Polysigma  uniforme  n.  sp.  Cuticle,  if  striated  at  all,  very  finely  so. 
Body  naked  except  for  the  setae  on  the  head.  Lips  minute,  more  or  less  conflu- 
ent, relatively  thick,  six  and  double,  or  possibly  twelve.  Near  the  nerve-ring 
and  just  in  front  of  the  cardiac  bulb,  the  oesophagus  is  one-half,  and  finally 
three-fourths,  as  wide  as  the  corresponding  portion  of  the  neck,  this  latter  figure 
being  the  measurement  of  the  pyriform  cardiac  bulb.  The  refractive  lining  is 
one-twentieth  as  wide  as  the  oesophagus.  In  the  posterior  half  of  the  oesoph- 


agus,  there  are  pigment  granules  in 
the  fine-textured  musculature.  The 
two  elongated  masses  of  brown  pig- 
ment granules  begin  suddenly  at  the 
middle  of  the  cardiac  bulb  and  end 
suddenly  near  the  middle  of  the  neck. 
There  are  quite  prominent,  pigmented 
submedian  glands  in  the  oseophagus, 
but  apparently  no  dorsal  one.  The 
thick-walled  intestine,  which  has  a 
faint  lumen,  becomes  at  once  half  as 
wide  as  the  body,  and  in  cross-section 
would  present  three  to  four  cells. 
Very  minute,  but  distinct,  yellowish 
granules  of  uniform  size  are  scattered 
in  the  intestinal  cells.  The  cardiac 
collum  is  two-fifths  as  wide  as  the 
X  750  neck.  The  medium-sized  nerve-ring 
is  accompanied  by  distinct  nerve  cells,  not  very  definitely  grouped.  From  the 
more  or  less  elevated  vulva,  the  fairly-well  cutinized  vagina  extends  inward  half 


POLYSIGMA,    ALAIMONEMA 


327 


way  across  the  body.     The  eggs  are  probably  about  three  times  as  long  as  the 
body  is  wide.     The  broad,  tapering  ovaries,  which  contain  about  ten  ova  arranged 


mostly  in  single  file, — but 
irregularly  near  the  blind 
end, — reach   about  half 
way  back  to  the  vulva.  mw 
The  tail  of   the  male    is 
conoid  to   the   spinneret,   Off  <M 
which  is  nearly  one-third 
as  wide  as  the  base  of  the 
tail   itself.     The   slightly 
yellowish,    rather   strong, 


mph 


subslender,    rather    acute 


X750 


cmm 


nn(3) 


spicula  appear  to  have  their  slightly  expanded  proximal  extremities  nearly  oppo- 
site the  body-axis.  There  are  seventy-six  yellowish,  refractive  supplementary 
organs  in  two  subventral  rows  of  thirty-eight  each.  They  are  subequidistant, 
but  somewhat  wider  apart  anteriorly.  They  appear  to  be  more  or  less  protrusile. 
Ejaculatory  duct  one-third  to  two-fifths,  the  testis  one-half,  as  wide  as  the 
body.  The  testis  is  cylindroid,  but  tapers  near  its  blind  end. 

Habitat:  Marine  mud,  twenty-five  fathoms  deep,  Woods  Hole,  Mass.,  U.  S.  A. 
Fig.  106a,  p.  326;  Fig.  1066. 

.5.     _2.7    s    5.7        "-H  95.    j21-. 

107.  Alaimonema  multicinctum  n.  sp.  i'.^  i.5"!"iVi" i.'i'^'i.'.*     '""  Striae  over 

1500  to  the  millimeter,  resolvable  with  difficulty  into  very  exceedingly  fine  dot- 
like  elements.  Cephalic  and  subcephalic  setae  sixteen,  in  four  sets  of  four. 
Cervical  setae  scattered,  the  first  four  to  eight  larger  than  the  cephalic  setae,  the 
others  smaller.  Somatic  setae  scattered,  inconspicuous,  about  one-sixth  as  long 
as  the  body  is  wide.  In  two  series  on  the  borders  of  the  lateral  fields,  every 
amph  t  set  sibcph  twenty  to  thirty  annules  throughout  the  nema, 
there  are  round,  pore-like  markings,  twice  as  wide 
as  the  annules.  The  two  rows  of  pores  opposite 
^ne  lateral  nelds  are  removed  from  each  other  by 
a  Distance  about  equal  to  three-fifths  the  body- 
diameter.  There  are  no  lips.  The  simple,  more  or 
jegg  triquetrous  pharynx  is  so  small  as  to  be  very 
easily  overlooked.  The  three  very  small  onchia  are  more  or  less  equal  in  size. 
Their  forward-pointing,  acute  apices  are  about  opposite  the  anterior  borders  of 
the  amphids.  The  oesophagus  is  at  first  three-fifths,  near  the  nerve-ring  and  in 
front  of  the  cardiac  bulb  two-sevenths,  and  finally  three-fourths,  as  wide  as  the 
corresponding  portion  of  the  neck.  The  pyriform  cardiac  bulb  contains  a  more  or 
less  spheroidal,  simple  valve,  two-sevenths  as  wide  as  the  bulb  itself.  The  oeso- 
phagus has  a  subdistinct,  narrow  lining,  and  a  fine  musculature.  The  intestine, 
which  has  a  more  or  less  thick  wall  and  a  faint  lumen,  soon  becomes  half  as  wide 
as  the  body.  In  cross-section  it  presents  but  few  cells.  The  cardiac  collum  is  one- 
fourth  as  wide  as  the  base  of  the  neck.  The  widest  of  the  variable,  colorless  gran- 
ules found  scattered  in  the  intestinal  cells  are  twice  as  wide  as  one  of  the  annules. 
The  longitudinal  fields  are  three-fifths  as  wide  as  the  body.  The  tail  is  conoid  from 
the  rather  prominently  raised  anus.  The  large,  rather  frail,  tapering,  somewhat 
blunt  spicula,  at  their  widest  parts,  near  the  proximal  ends,  are  one-fourth  as 
wide  as  the  corresponding  portion  of  the  body.  There  is  a  rather  frail,  slender 
accessory  piece.  The  elevated,  "campanulate,"  subequidistant  supplementary 
organs  begin  opposite  the  proximal  parts  of  the  spicula  and  are  stationed  at  a 


328  ORDER   ANAXONCHIA 

distance  from  each  other  varying  from  one-sixth  of  one,  to  one,  entire  body- 
diameter.  The  organs  are  nearly  as  high  as  they  are  wide,  and  are  more  or  less 
asymmetrical.  Each  is  connected  with  an  internal,  refractive  piece,  a  little 
farther  forward.  They  somewhat  resemble  the  well-developed  supplementary 
organs  of  Chromadora.  The  ejaculatory  duct  is  one-half,  the  vas  deferens  three- 
fifths,  as  wide  as  the  body.  A  considerable  portion  of  the  male  sexual  organs  is 
filled  with  spherical  granular  spermatocytes,  one-third  as  wide  as  the  body,  and 
having  a  distinct  ectosarc. 

Habitat:  Beach  sand,  Bathing  Beach,  Woods  Hole,  Mass.,  U.  S.  A.     Flemming 
to  water.  Fig.  107,  p.  327. 

.6       10.5      tf-  -*-*'       95.    >.  6 

108.  Cophonchus  ocellatus  n.  sp.  i._/  1.9  *•«  3-  T^i-9  '  Transverse 
striae  exceedingly  minute;  the  cuticle  is  also  longitudinally  striated.  The  some- 
on  what  cylindroid  neck  is  almost  imperceptibly  convex- 
conoid  in  its  anterior  part.  Cuticle  relatively  thicker 
on  the  head.  A  few  short  setae  occur  here  and  there  on 
the  neck.  There  appear  to  be  three  somewhat  confluent 
lips  with  papillae  on  their  outer  margins,  probably  to 
the  number  of  six.  There  are  two  dark-brown  dorsally 
\~aiSC  submedian  eye-spots  and  opposite  them  in  the  ventral 
portion  of  the  oesophagus  a  linear  collection  of  pig- 
^  mented  granules,  from  which  there  also  extends  backward 
a  line  of  scattered  granules.  Similar  granules  occur 
1  ^throughout  the  oesophagus  in  groups  of  a  score  or  more. 
Spear-like  onchium  very  slightly  sigmoid.  It  is  probable  that  the  pharynx 
extends  back  to  opposite  the  row  of  cephalic  setae.  The  cuticle  on  the  anterior 
surface  of  the  head,  as  far  back  as  the  cephalic  setae  or  a  little  farther,  reminds 
one  of  the  covering  on  the  head  in  Thoracostoma,  but  the  thickening  is  less  pro- 
nounced, and  the  cuticle  here  is  not  materially  different  in  color  or  texture  from 
that  elsewhere  on  the  body.  Where  the  cuticle  reaches  its  maximum  thickness, 
near  the  lips,  it  is  three  to  four  times  as  thick  as  elsewhere  on  the  body.  From 
this  point  backward  to  near  the  base  of  the  head,  it  gradually  grows  thinner. 
The  oesophagus  continues  to  have  the  same  diameter  until  after  it  passes  through 
the  nerve-ring;  there  it  begins  to  enlarge,  so  that  finally  it  is  two-fifths  as  wide 
as  the  base  of  the  neck.  The  intestine,  set  off  by  a  deep  constriction,  becomes 
at  once  about  two-thirds  as  wide  as  the  body.  Its  cross-section  would  present 
four  to  six  cells  packed  with  minute  granules.  The  conoid  cardia  is  one-fourth 
as  wide  as  the  corresponding  portion  of  the  body.  The  renette  cell  is  about 
half  as  wide  as  the  body,  and  is  located  on  the  ventral  side  just  in  front  of  the 
cardia;  its  pyriform  ampulla  is  one- fifth  as  wide  as  the  corresponding  portion  of 
the  neck.  The  lateral  fields  appear  to  be  about  one-third  as  wide  as  the  body, 
and  to  contain  numerous,  rather  small,  scattered  nuclei.  The  nerve-ring  sur- 
rounds the  oesophagus  squarely.  Tail  of  the  male  conoid  in  the  anterior  four- 
fifths;  thence  cylindroid  for  a  short  distance  to  the  almost  imperceptibly  swollen 
terminus.  The  caudal  glands  are  apparently  located  opposite  to  and  a  little 
behind  the  anus,  and  present  the  peculiarity  that  one  of  them,  the  one  on  the 
ventral  side,  has  a  separate  duct  leading  to  the  separate  smaller  ampulla  in  the 
slightly  enlarged  spinneret,  while  the  other  two  have  their  ducts  parallel  and 
close  together  and  appear  to  join  in  a  single,  much  larger  ampulla  opposite  the 
smaller  one.  From  these  ampullae,  minute  ducts  lead  backward  to  the  pore 
of  the  spinneret,  which  presents  a  minute,  conoid  depression  on  the  terminus. 
Supplementary  organ  tubular,  of  about  the  same  diameter  as  the  spicula,  extend- 


COPHONCHUS,    ISONEMELLA  329 

ing  first  inward,  then  directly  forward.  It  is  about  one-third  as  long  as  the  cor- 
responding body-diameter.  Its  outlet  is  opposite  the  middle  of  the  spicula. 
There  appear  to  be  some  obscure  papillae  on  the  tail,  evidenced  by  almost  imper- 
ceptible ventral  elevations.  Mention  may  be  made  of  one  of  these  near  the 
beginning  of  the  middle  third,  and  another  near  the  beginning  of  the  posterior 
third.  Spicula  slender,  uniform,  acute,  one  and  one-half  times  as  long  as  the 
tail,  and  five  to  six  times  as  long  as  the  anal  body-diameter.  Their  proximal 
ends  are  cephalated  by  expansion.  They  are  accompanied,  both  in  front  and 
behind,  at  their  distal  extremities,  by  accessory  pieces  two-thirds  as  long  as  the 
anal  body-diameter.  The  ejaculatory  duct  is  one-fourth  as  wide  as  the  body, 
and  extends  forward  to  near  the  middle  of  the  body,  where  it  joins  the  testes. 

Habitat:  Shoal  in  Kingston  Harbor,  Jamaica,  in  about  one  foot  of  water.     This 
genus  bears  a  very  considerable  resemblance  to  Digitonchus.     Fig.  108,  p.  328. 


109.  Isonemella    acuta    n.   sp.    '7/  Body-wall  thick 

and  muscular;  in  the  middle  of  the  single  specimen  seen  it  takes  up  about  three- 
fifths  of  the  radius.  There  are  a  few  exceedingly  minute  setae  to  be  seen  on 
the  tail;  otherwise  than  these,  and  those  shown  in  the  illustration,  no  others  are 
known.  There  appear  to  be  three  lips,  but  they  are  so  small  and  so  thoroughly 
amalgamated  that  it  is  very  difficult  to  decide  on  their  structure,  and  it  is  possible 
that  there  is  no  division  of  the  margin  of  the  mouth  into  lips.  The  mouth  opening 
is  nearly  as  wide  as  the  front  end  of  the  head.  Between  the  thin  lips  there  is  a 
very  short  vestibule,  whose  limits  are  marked  by  the  presence  of  an  internal 
refractive  structure  on  the  inner  wall  of  the  pharynx  very  near  the  margin  of  the 
lips.  It  is  impossible  to  say  from  the  observations  so  far  made  whether  this 
refractive  marking  is  a  circular  affair  or  whether  it  is  dis-  setl/ffl 
continuous  and  represents  special  thickenings  on  the  inner  ^ 
surface  of  the  three  components  of  the  lip-region.  The 
result  of  this  thickening  is  a  sudden,  but  very  slight  nar-  amP" 
rowing  of  the  vestibule.  The  very  short  vestibule,  there-  DC  . 
fore,  begins  nearly  as  wide  as  the  front  of  the  head,  widens  ^ 
out  posteriorly  and  then  soon  suddenly  narrows  to  the 
beginning  of  the  pharynx  proper.  At  its  base  this  lat-  *" 
ter  tapers  to  join  the  lumen  of  the  oesophagus.  At 
first  sight  it  appears  that,  with  the  exception  of  the  above- 
mentioned,  excessively  minute,  cutinized  processes  at  the 
base  of  the  vestibule,  the  pharynx  does  not  present  any 
feature  suggestive  of  a  particular  armature,  but  there  is  spn  x750 

nevertheless  a  minute,  forward-pointing  ventral  (?)  onchium  of  small  size.  The 
walls  of  the  pharynx,  though  distinctly  outlined  by  the  refractive  nature  of 
the  cuticle,  are  very  thin  throughout.  The  lip-region  stains  more  strongly 
than  any  of  the  succeeding  tissues  of  the  head,  or  of  the  anterior  part  of  the 
neck.  All  that  portion  of  the  lip-region  in  front  of  the  middle  of  the  pharynx 
takes  part  in  this  staining,  and  the  posterior  contour  of  the  stained  portion 
extends  outward  and  backward  from  the  front  part  of  the  pharynx.  Behind 
this  stained  portion,  indicated  in  the  illustration,  there  are  two  elongated  "cavi- 
ties," beginning  opposite  the  middle  of  the  pharynx  and  ending  a  little  behind 
the  eye-spots,  one  dorsal  and  one  ventral,  and  the  outer  contour  of  the  head 
opposite  these  "cavities"  is  very  slightly  elevated,  in  the  single  specimen  so  far 
examined.  When  viewed  in  profile  these  "cavities"  have  a  size  and  contour 


330  ORDER   ANAXONCHIA 

somewhat  similar  to  that  of  the  pharynx.  The  amphids,  difficult  to  observe, 
have  a  somewhat  elongated,  inward,  refractive  extension,  as  shown  in  the  illus- 
tration. Eye-spots  colorless  or  slightly  yellow.  There  are  rather  inconspicu- 
ous collections  of  golden  brown  pigment  granules  in  the  anterior  portion  of  the 
oesophagus.  This  latter  continues  with  much  the  same  diameter  for  some  dis- 
tance, but  gradually  enlarges.  After  it  passes  through  the  nerve-ring  it  is  two- 
fifths  as  wide  a's  the  corresponding  portion  of  the  neck,  and  it  finally  becomes 
three-fifths  as  wide  as  the  base  of  the  neck.  Its  radial  musculature  is  very 
strongly  marked  in  the  posterior  half,  reminding  one  to  some  extent  of  the  oesoph- 
agus in  Bolbella.  The  nerve  cells  both  before  and  behind  the  nerve-ring  are  an 
unusually  prominent  feature.  A  little  more  than  half  way  from  the  head  to  the 
nerve-ring  the  foremost  of  these  cells  occur  as  two  lateral  ellipsoidal  granular 
cells  half  as  wide  as  long,  and  having  a  length  one-third  as  great  as  the  corre- 
sponding width  of  the  neck.  Almost  on  a  level  with  these  is  a  ventral  cell,  and 
immediately  behind  them  are  other  lateral  cells  of  somewhat  smaller  size,  and 
thence  onward  the  neck  is  packed  with  cells  of  the  same  character,  which  gradu- 
ally become  globular  and  continue  behind  the  nerve-ring  and  cease  about  half 
way  between  the  nerve-ring  and  the  cardia.  There  is  a  collection  of  similar  cells 
in  front  of  and  behind  the  anus.  The  cardia  is  convex-conoid  and  about  one- 
third  as  wide  as  the  corresponding  portion  of  the  body.  The  intestine  becomes 
at  once  about  two-  to  three-fifths  as  wide  as  the  body.  The  anus  is  almost 
continuous,  though  the  posterior  lip  is  very  slightly  raised.  The  refractive, 
narrow  rectum  is  about  one  and  one-half  times  as  long  as  the  anal  body-diameter. 
The  tail  begins  to  taper  from  a  little  in  front  of  the  anus,  and  tapers  at  much  the 
same  rate  behind  the  anus,  in  such  a  fashion  that  at  its  middle  the  diameter  is 
about  one-third  as  great  as  at  its  base;  thence  onward,  it  tapers  but  little  and 
ends  in  a  terminus  about  one-fourth  as  wide  as  its  base.  Caudal  glands  appear 
to  be  located  in  the  base  of  the  tail.  The  renette  cell  is  located  just  behind  the 
base  of  the  neck.  The  lateral  fields  appear  to  be  about  one-half  as  wide  as  the 
body,  and  are  characterized  by  a  succession  of  groups  of  cells,  which  are  larger 
than  usually  seen  in  these  regions.  These  groups  contain  dozens  of  nuclei  packed 
rather  closely  together.  The  groups  do  not  seem  to  be  very  regularly  arranged, 
but  succeed  each  other  with  intervals  between  them  that  are  shorter  than  the 
length  of  the  groups.  The  groups  are  of  rather  uneven  size,  and  are  most  con- 
spicuous between  the  neck  and  the  anus. 
Habitat:  Larat,  East  Indies.  Marine.  Fig.  109,  p.  329. 

.7        5.6          9.        S-W.          ».7 


110.  Synonema  braziliense  n.  sp.  1.3 /    i.5       ij         l-s       J-2  Cuticle  naked 

except  for  the  setae  at  the  anterior  end.  Mouth  depressed.  Lips  subdistinct, 
flat,  rather  thin,  fairly  developed,  flap-like;  lip-region  apparently  twelve-ribbed, 
closing  nearly  together  over  the  rather  small  pharynx,  which  may  be  reckoned 
to  extend  at  least  a  short  distance  behind  the  base  of  the  dorsal  onchium.  The 
oesophagus  near  the  nerve-ring  is  one-half,  just  in  front  of  the  cardiac  bulb  one- 
half,  and  finally  three-fourths,  as  wide  as  the  base  of  the  neck.  This  latter 
measurement  represents  the  diameter  of  the  valveless,  pyriform  cardiac  bulb. 
The  musculature  of  the  oesophagus  is  colorless,  with  no  indication  of  the  pres- 
ence of  glands.  There  is  a  cylindroid  cardia  one-third  to  two-fifths  as  wide  as 
the  base  of  the  neck,  and  two-thirds  as  long  as  the  body  is  wide.  The  thick-walled 
intestine,  which  has  a  distinct,  refractive  lining,  becomes  at  once  three-fourths 
as  wide  as  the  body,  and  in  cross-section  would  present  about  four  cells.  Cardiac 
collum  one-half  as  wide  as  the  neck.  From  the  more  or  less  depressed  anus,  the 


SYNONEMA,  ANTIC YCLUS  331 

prominent  cutinized  rectum  extends  inward  a  distance  equal  to  the  anal  body- 
diameter.  Anal  muscles  are  dimly  to  be  seen.  The  intestinal  cells  have  conspic- 
uous nuclei,  and  as  there  is  an  almost  entire  absence  of  granules,  the  intestine 
is  very  transparent.  Tail  arcuate,  conoid.  The  three  saccate  caudal  glands 
form  a  close  tandem  in  the  anterior  half  of  the  tail;  they 
empty  through  separate  ducts  and  ampullae.  No  caudal 
setae  are  to  be  seen.  The  lateral  fields  have  not  been 
clearly  seen;  they  are  probably  one-third  as  wide  as  the 
body  and  composed  mainly  of  two  rows  of  cells.  The 
granular  renette  cell  is  three  times  as  long  as  the  body  is 
wide  and  one-sixth  as  wide  as  long.  It  is  placed  from  two 
to  six  body-widths  behind  the  neck,  and  seems  to  be  com- 
posed of  about  six  ellipsoidal,  granular  cells,  arranged  more  or  less  in  pairs. 
The  excretory  pore  is  two-fifths  the  way  back  to  the  nerve-ring;  there  is  no 
ampulla.  The  nerve-ring  is  accompanied  by  distinct  nerve  cells  arranged  in 
groups.  The  following  description  of  the  sexual  organs  is  derived  from  an 
immature  specimen:  The  tubular,  muscular,  more  or  less  cutinized  vagina 
extends  obliquely  forward  two-thirds  the  distance  across  the  body,  where  it 
joins  the  straight  uterus,  which  is  about  twice  as  long  as  the  body  is  wide.  Ova 
prolate;  the  maturest  six  to  eight  being  arranged  single  file,  the  others  irregu- 
larly,— about  thirty  in  all.  Ovary  medium-sized  and  tapering.  Male  unknown. 
Habitat:  Algae,  near  lighthouse,  Bahia,  Brazil.  Sublimate  to  balsam.  The 
multicellular  renette  is  highly  peculiar.  Fig.  110. 

111.  Anticyclus  exilis  n.  sp.    Cephalic  setae  sixteen,  subcephalic  four;  cuticle 

otherwise  naked.     The  rather  thin  lips,  apparently  six  in  number,  arch  together 

over  the  pharynx,  somewhat  as  in  Oncholaimus.     According  to  the  state  of  the 

muscular  contraction   in   the  lips,    the   head   is 

_J — ti — ^1 -i|_ — 55^  >  2.2-  slightly  convex  on  the  front  surface,  or  slightly 

70  concave.     Margins  of  the  amphids  strongly  refrac- 

•jj* — |;^    H Tsu-vts*2-9"  tive>  so  that  their  contours  are  exceedingly  dis- 
tinct.   At  first,  the  oesophagus  has  a  diameter 

fully  two-thirds  as  great  as  that  of  the  corresponding  portion  of  the  neck,  and 
it  retains  this  diameter  until  after  it  passes  through  the  nerve-ring;  about  half 
way  between  the  nerve-ring  and  the  intestine,  it  begins  to  expand,  and  continues 
to  do  so  very  gradually,  so  that  finally  it  is  about  three-fourths  as  wide  as  the 
base  of  the  neck.  The  anterior  cells  of  the  intestine  are  more  transparent  and 
otherwise  different  in  appearance  from  those  which  succeed,  and  it  not  infre- 
quently happens  that  they  present  a  strong  resemblance  to  the  oesophagus, 
so  that  the  real  position  of  the  cardiac  constriction  is  likely  to  be  mistaken. 
The  intestine  is  at  first  about  two-thirds  as  wide  as  the  body.  It  soon,  how- 
ever, becomes  three-fourths  to  four-fifths  as  wide  as  the  body,  and  is  composed 
of  rather  massive  cells,  so  that  the  lumen  is  narrow.  Its  cross-section  prob- 
ably presents  about  six  cells.  These  contain  numerous  granules,  rather  uni- 
form in  size  and  so  arranged  as  to  give  rise  to  an  indistinct  tessellation.  From 
the  inconspicuous  anus,  the  rectum,  which  has  about  the  same  length  as  the 
anal  body-diameter,  extends  inward  and  forward.  The  lateral  fields  are  one- 
third  as  wide  as  the  body.  Renette  unknown;  it  is  possible  that  the  renette  cell 
is  unusually  small  and  located  near  the  cardiac  constriction.  The  tail  of  the 
female  is  supposed  to  be  like  that  of  the  male  described  below,  but  there  is 


332  ORDER   ANAXONCHIA 

uncertainty  on  this  point,  as  all  the  female  specimens  so  far  examined  have 
lacked  the  posterior  portion  of  the  tail;— the  portion  present  has  the  same  form 
as  the  corresponding  portion  of  the  tail  of  the  male.  From  the  inconspicuous 
vulva,  the  vagina  leads  inward  and  probably  slightly  forward.  The  eggs  are 
about  three  to  four  times  as  long  as  the  body  is  wide  and  about  one-fourth  as  wide 
as  long.  The  tail  of  the  male  is  conoid  in  the  anterior  fourth  in  such  fashion 
that  at  the  beginning  of  the  second  fourth,  its  diameter  is  about  one-third  as  great 
as  at  the  anus;  thence  onward,  it  tapers  much  less  rapidly,  and  in  the  posterior 
half  hardly  tapers  at  all,  the  diameter  for  a  considerable  distance  in  front  of  the 
terminus  being  no  greater  than  that  of  the  thickness  of  the  body-wall.  There 
is  present  behind  the  anus  a  collection  of  cells  which  bear  some  resemblance 
to  caudal  glands,  but  whether  they  really  are  caudal  glands  and  empty  through 
a  spinneret  at  the  terminus  remains  uncertain.  The  seventeen  equidistant 
supplementary  organs  are  rounded,  low,  conoid  papillae  separated  by  distances 
about  equal  to  their  own  diameters,  and  occupy  a  distance  from  two  to  three 
times  as  great  as  the  corresponding  body-diameter.  These  organs  appear  to  be 
innervated,  but  they  at  times  closely  resemble  mere  transverse  corrugations 
of  the  cuticle.  Behind  the  anus,  at  least  when  the  tail  is  incurved,  there  are 
folds  in  the  cuticle  that  present  a  very  similar  appearance  to  those  just  described 
as  supplementary  organs,  occurring  in  front  of  the  anus;  these  are  confined  to 
the  wide  and  muscular  portion  of  the  tail,  and  do  not  extend,  as  a  rule,  as  far 
backward  as  the  corresponding  appearances  in  front  of  the  anus  extend  forward. 
Spicula  somewhat  longer  than  the  anal  body-diameter, 
more  strongly  arcuate  toward  their  proximal  extremities 
than  near  the  anus.  They  extend  about  two-thirds  the 
distance  across  the  body  and  then  curve  around  toward 
body-axis.  There  extend  from  the  proximal  ends 
toward  the  anus  nearly  straight  refractive  elements  that 
'^fofii  pill  06  mav  possibly  indicate  that  the  spicula  are  much  wider 
V-^^ffil  ™  *^e  middle  than  at  either  extremity.  The  spicula  are 

accompanied  by  accessory  pieces  which  extend  inward 
f  7"tt4ifx  IdWluin 06  from  the  anus  pretty  nearly  at  right  angles  and  end  near 
the  body-axis.  The  ejaculatory  duct  is  two-fifths  as  wide  as  the  body.  Pos- 
terior testis  much  the  smaller. 

Habitat:  Bath  Tub  Springs,  Jamaica,  near  Salt  River.  These  are  salt  springs 
having  about  body  temperature.  Fig.  111. 

_1._6  _  _5.3_  jqa  _  _^'_61t^  _  J5  9  ^ 

112.  Croconema  cinctum  n.  sp.  2.3  2.6/(,,  2.6  3.6  i.s72"  "  Cuticle  thick 
transparent,  yellow,  composed  of  about  500  annules  imparting  to  the  contour 
of  the  body  throughout  a  distinctly  crenate  appearance,  and  bearing  numerous 
short,  stiff,  slightly  curved  bristles,  having  a  length  somewhat  greater  than  its 
own  thickness.  The  cuticle  of  the  head  seems  to  consist  of  a  single,  somewhat 
hemispherical  helmet-like  piece.  In  all,  there  must  be  at  least  six  irregular  longi- 
tudinal rows  of  setae  on  the  "helmet,"  but  it  seems  impossible  to  pick  out  any 
single  circlet  of  these  setae  that  particularly  merit  the  term  cephalic  setae. 
The  spreading  setae  on  the  neck  curve  backward.  Both  here  and  toward  the 
tail  end,  these  setae  are  shorter  than  near  the  middle  of  the  body  where  they 
are  tapering,  acute,  nearly  twice  as  long  as  the  cuticle  is  thick  and  have  a  base 
one-fourth  as  wide  as  the  distance  between  two  successive  annules  of  the  cuticle. 
When  the  mouth  is  closed,  the  tips  of  the  lips  are  bunched  at  the  middle  of  the 
front  of  the  head.  There  appear  to  be  about  twelve  of  these  tips.  The  pharynx 


CROCONEMA 


333 


is  about  one-eighth  as  wide  as  the  base  of  the  head  and  is  fairly  well  filled  by 
the  apices  of  the  teeth.  Two  of  these  onchia  (?)  have  been  distinctly  seen, 
a  dorsal  one  which  extends  to  the  base  of  the  lips  and  has  a  subacute,  conical, 
refractive  apex,  and  whose  base  is  about  one-eighth  as  wide  as  the  corresponding 
diameter  of  the  head,  and  a  larger  submedian  one  with  a  conical,  refractive 
apex,  and  having  a  base  somewhat  wider  than  that  of  the  dorsal  one.  This 
latter  has  a  length  somewhat  greater  than  the  width  of  the  amphids,  and  its  base 
lies  near  the  center  of  the  head  and  rather  behind  the  middle  of  the  pharyngeal 

bulb.    The   pharynx    is   strongly  aaipli  on          f Ib  setqih 

cutinized,  and  manifestly  extends 
backward  through  the  greater  part 
of  the  region  surrounded  by  the 
"helmet."  The  rather  obscure 
change  from  pharynx  to  oesoph- 
agus takes  place  suddenly  along 
two  loci  which  extend  obliquely 
outward  and  forward  from  the 
lumen  of  the  oesophagus.  The 
oesophagus  retains  the  same  diam- 
eter until  after  it  passes  through 
the  nerve-ring;  soon  after  that  it 
begins  to  enlarge  gradually  in 
diameter,  so  that  finally  it  is  three- 
fourths  as  wide  as  the  base  of  the  X  750 
neck.  The  intestine  is  at  first  very  narrow,  about  one-fifth  as  wide  as  the  body, 
and  for  a  short  distance  has  a  different  structure  from  the  portion  that  follows. 
Possibly  this  first  part  should  be  considered  a  cardia.  In  this  cardiac  portion, 
there  are  no  cells  containing  granules.  Immediately  behind  the  "cardiac" 
portion,  the  intestine  is  half  as  wide  as  the  body  and  would  present  eight  to 
ten  cells  in  cross-section.  The  cells  contain  brownish  granules  of  uniform  size, 
so  arranged  as  to  give  rise  to  a  distinct  tessellation.  The  intestine  is  moder- 
ately thick-walled.  From  the  raised  anus,  the  strongly  cutinized  rectum,  which 
is  somewhat  longer  than  the  anal  body-diameter,  extends  inward  and  then 
almost  directly  forward,  so  that  it  joins  the  intestine  considerably  ventrad  from 
the  body-axis.  The  tail  is  arcuate-conoid,  and  presents  the  peculiarity  that 
the  annules  of  the  cuticle  cease  in  front  of  the  middle;  thence  onward,  the  cuticle 
is  considerably  thicker  and  is  traversed  by  radial  markings,  which  pass  out- 
ward and  a  little  backward  and  give  to  the  surface  of  this  portion  of  the  tail 
a  distinctly  punctate  appearance,  which,  however,  is  less  marked  than  the 
similar  appearance  on  the  head.  The  caudal  glands  are  arranged  tandem  imme- 
diately in  front  of  the  anus,  extending  from  the  end  of  the  intestine  proper  to 
a  little  behind  the  anus.  There  is  apparently  a  small  renette  cell  imme- 
diately behind  the  oesophagus.  The  nerve-ring  surrounds  the  oesophagus 
obliquely.  From  the  slightly  elevated,  rather  inconspicuous  vulva  the  vagina 
extends  nearly  half  way  across  the  body.  The  ovaries  reach  more  than  half 
way  back  to  the  vulva,  and  contain  a  dozen  to  twenty  developing  ova,  arranged 
irregularly. 

Habitat:  Sand  and  marine  algae,  in  surf,  shore  of  small  island  off  Port  Eoyal, 
Jamaica.     Fig.  112. 


334  ORDER   ANAXONCHIA 

113.  Nudora  lineata  n.  sp.  Cuticle  two  to  three  times  as  thick  at  the  head 
end  as  elsewhere;  more  or  less  like  that  of  Desmodora,  but  with  longitudinal 
striae  somewhat  like  those  of  Monoposthia.  The  annules  increase  in  width, 
and  are  more  accentuated,  toward  the  head.  Each  of  the  ten  longitudinal  wings 
appears  to  comprise  a  series  of  "V"-like  markings  on  the  anterior  portion  of 
the  body,  which  are  reversed  on  the  posterior.  Following  the  serrate  contour 
of  the  head  it  is  discovered  that  this  reversal  takes  place  not  far  behind  the 
neck.  There  seem  to  be  twelve,  subdistinct,  more  or  less  conoid,  minute,  blunt 
labial  elements.  The  labial  papillae  are  more  or  less  setose,  one  seta  between 
each  pair  of  labial  elements.  Limits  of  the  pharynx  rendered  very  definite  on 
account  of  the  elongated  pharyngeal  swelling.  Anterior  part  of  the  pharynx 
cyathiform,  posterior  triquetrous-tubular.  Posterior  part  of  the  neck  cylin- 

setqM4)  J-l-l-W13---:?9 ?2l"  >i.76..  droid,  anterior  convex-co- 

lh\\     ;V\ktf*^^ •     "I/A    '"  noid.     The  amphids  appear 

1     J-l  _  1-^t.  _  _  _* »y  >:  48     to  be  oylindroid  depressions 

E.2         2.9         3.2  3.4     r^Z.?  «  ,  ,,  ,.    , 

about  as  deep  as  the  cuticle 

is  thick.  In  front  of  the  wide  annule  bearing  the  amphids, 
there  is  another  about  as  wide  as  those  on  the  neck, 
which,  however,  does  not  thin  out  on  its  anterior  edge, 
X756  "^^strJongity  spn  as  do  the  regular  annules.  Following  this  annule  comes 
the  lip-region,  which  in  contra-distinction  takes  a  carmine  stain.  The  elon- 
gated, pharyngeal  bulb,  one-half  as  wide  as  the  neck,  is  set  off  from  the  remainder 
of  the  oesophagus  by  a  constriction.  The  oesophagus  is  at  first  one-third,  near 
the  nerve-ring  one-third,  preceding  the  cardiac  bulb  one-third,  and  finally  five- 
sixths,  as  wide  as  the  corresponding  portion  of  the  neck.  The  cardiac  bulb  is 
cylindroid  and  makes  up  one-third  of  the  oesophagus.  Its  musculature  is  coarse 
and  colorless.  The  oesophageal  tube  expands  suddenly  to  form  the  cardiac 
bulb,  which  is  divided  into  two  main  parts  by  a  break  in  its  musculature.  There 
are  smaller  breaks,  also,  near  each  end.  The  lining  of  the  oesophagus  appears 
to  occupy  one-sixth  of  its  width.  The  rather  thin-walled,  narrow  intestine 
becomes  at  once  one-fifth  as  wide  as  the  body.  At  the  cardiac  constriction  the 
intestine  joins  the  center  of  the  posterior  surface  of  the  oesophageal  bulb. 
Minute  granules  are  scattered  in  the  intestinal  cells.  The  conoid  tail,  on  which 
there  are  obscure  longitudinal  striae,  tapers  from  the  anus  to  the  non-striated, 
simple,  symmetrical  spinneret.  The  broadly  saccate  caudal  glands  form  a  close 
tandem  in  the  anterior  half  of  the  tail.  Slender  caudal  setae  occur  on  the  tail 
end,  both  preanal  and  postanal,  three  to  four  ventrally  submedian,  and  three  to 
four  dorsally  submedian.  just  in  front  of  as  well  as  behind  the  anus,  about  one 
and  one-half  body-widths  apart,  and  shorter  on  the  male  than  on  the  female. 
The  rather  broad  ovary  tapers  near  its  blind  end.  The  flattish  ova  are  arranged 
for  the  most  part  single  file.  The  spicula  are  frail,  very  slender,  mostly  uniform, 
but  finally  tapering  and  acute.  Their  proximal  ends  appear  to  lie  about  opposite 
the  body-axis.  The  yellow  accessory  pieces  are  somewhat  longer  than  the 
spicula.  They  are  arcuate  and  stoutish,  and  their  proximal  ends  appear  to  lie 
somewhat  dorsad  from  the  body-axis.  There  are  two  obscure  supplementary 
organs,  the  anterior  of  which  is  located  at  a  distance  in  front  of  the  anus  equal 
to  one  and  one-half  body-diameters,  the  posterior  being  opposite  the  middle  of 
the  spicula.  These  consist  of  slight  elevations  further  accentuated  by  small 
alterations  in  about  three  consecutive  annules. 
Habitat:  Sand,  below  low  tide  mark,  Hull,  Massachusetts,  U.  S.  A.  Fig.  113. 


RHINEMA  335 

114.  Rhinema  retrorsum  n.  sp.  Cuticle  thick,  interrupted  at  twelve  places  so 
as  to  form  exceedingly  distinct  longitudinal  wings,  which  when  brought  into 
focus  give  a  somewhat  "fishbone "-like  effect.  The  annules  and  their  modifica- 
tions give  a  retrorse  appearance  to  the  entire  cuticle,  but  in  reality  the  striae 
are  retrorse  in  the  posterior  part  of  the  body,  and  the  reverse  in  the  anterior  part. 
Some  of  the  cuticular  markings  cease  in  front  of  the  anus  on  the  male  and  are 
not  continued  on  the  tail,  so  that  the  tail  has  a  somewhat  unusual  appearance. 
There  are  submedian  longitudinal  striations  extending  to  the  middle  of  the 
tail.  Neck  for  the  most  part  cylindroid.  Opposite  the  dorsal  tooth  there 
is  a  distinct  junction  with  the  cuticle  of  the  lip-region  indicated  by  an  almost 
imperceptible  constriction  encircling  the  head.  In  front  of  this  constriction 
there  are  two  others,  close  together,  connected  with  the  lip-region.  Lips  with 

outward-curved  api-  j.£  _io.  ___». l''5?'l*_  J>i-* 

ces,    surrounding   a  ^      2'8     3" 

cyathiform   cavity  J-L  _  M^J?^ r^n  _  _?Ai-  >"12,. 

having  a  diameter  2'-9      3'5     «         ^  ~*  •¥»    JUKSJH*  ,  *,*• 

about  three-fifths  as  great  as  that  of  the  front  of  J^Wlj/jj||  iH^JrifQfflfc 
the  head,  and  a  depth  not  more  than  half  that 
amount.  Into  the  midst  of  this  shallow  cavity  the 
dorsal  onchium  projects.  Sometimes,  however,  this  p/L. 
cavity  is  deeper,  namely,  when  the  dorsal  tooth  is 
withdrawn  to  a  greater  extent.  Then  the  cavity 
is  about  half  as  wide  as  the  head,  and  about  as  deep  75°  *  lmlte  'apndal^Lpspn 
as  wide,  and  the  lip-region  is  manifestly  more  closely  folded.  Onchium  faintly 
spear-like.  Muscles  of  the  pharynx  of  an  entirely  different  character  from 
those  of  the  oesophagus,  which  begins  as  a  tube  about  half  as  wide  as  the  cor- 
responding portion  of  the  neck,  and  continues  to  have  this  diameter  until  after 
it  passes  through  the  nerve-ring,  thereafter  expanding  gradually,  but  finally 
somewhat  faster,  so  that  at  the  end  it  becomes  two-thirds  as  wide  as  the  base 
of  the  neck.  The  posterior  swelling  is  of  such  a  character  that  one  might  speak 
of  it  as  a  bulb.  There  is  no  very  distinct  cardia.  Renette  unknown.  Vagina 
reaching  half  way  across  the  body.  Mature  ova  at  the  flexure,  ready  to  enter 
the  uterus,  are  one  and  one-half  times  as  long  as  the  body  is  wide  and  about  half 
as  wide  as  long,  with  nuclei  one-third  as  broad  as  themselves.  The  narrow  ova- 
ries are  more  or  less  cylindroid  and  contain  comparatively  few  ova,  apparently 
arranged  more  or  less  single  file.  Anus  of  the  male  distinctly  raised.  Tail 
arcuate  and  conoid  to  the  naked  terminus,  which  has  a  length  about  equal  to 
that  of  five  of  the  preceding  annules.  Position  of  the  caudal  glands  doubtful, 
but  it  seems  quite  possible  that  they  are  located  in  the  base  of  the  tail.  There 
are  a  few  inconspicuous  hairs  on  the  smooth  terminus  that  are  not  shown  in  the 
illustration,  of  which  two  have  been  seen  in  the  ventrally  submedian  position, 
having  a  length  about  two-thirds  as  great  as  the  corresponding  diameter  of  the 
terminus.  No  supplements  or  special  papillae  or  setae  have  been  seen,  though 
it  is  possible  that  very  small  setae  may  have  escaped  observation.  The  slender, 
slightly  arcuate,  rather  uniform  spicula  have  their  proximal  ends  almost  imper- 
ceptibly cephalated  by  expansion.  The  uniform  proximal  three-fourths  of  the 
spicula,  when  viewed  in  profile  appear  to  have  approximately  the  width  of  one 
of  the  adjacent  annules.  In  the  distal  fourths  the  spicula  taper  to  an  acute 
point.  There  is  a  single,  nearly  straight  but  slightly  "S "-shaped  accessory 
piece,  two-thirds  as  long  as  the  spicula,  which  is  acute  at  its  distal  extremity 
and  capable  of  protrusion  to  a  certain  extent.  It  is  fully  as  wide  as  the  spicula. 


336  ORDER   ANAXONCHIA 

Its  proximal  half  curves  away  from  the  spicula  and  then  recurves,  and  is  con- 
nected with  the  ventral  part  of  the  body-wall  a  short  distance  behind  the  anus 
by  means  of  oblique  muscles. 

Habitat:  Coral  sand,  New  Hebrides.  This  genus  differs  from  Chromadora, 
Spilophora  and  Euchromadora  in  the  possession  of  distinct  circular  amphids, 
and  also  in  the  possession  of  twelve  longitudinal  cuticular  costae.  In  this  latter 
respect  it  resembles  Monoposthia,  but  here  the  spicula  are  double,  and  there 
are  no  supplementary  organs  or  swellings.  The  lip-region  and  pharynx  also  pre- 
sent contrasts  with  any  of  the  above  genera.  The  striking  differences  are:  (1) 
The  continuation  of  the  pharynx  in  its  narrow  part  as  a  definite  well  lined  pos- 
terior chamber,  ending  definitely  opposite  the  point  where  the  pharyngeal  bulb 
is  separated  from  the  oesophagus  by  a  distinct  constriction.  (2)  By  the  form  of 
the  lips,  which,  instead  of  being  soft  and  internally  folded  so  as  to  give  rise  to 
about  twelve  refractive  ribs,  or  folds,  are  more  strongly  built,  cutinized  and  out- 
wardly recurved,  and  are  only  six  in  number.  (3)  -M-Fig.  114,  p.  335. 

A-.5. . .  9.7 .;.  i6:6  ...'*-* aq. .  4>  4  _ 

115.  lotadorus  punctulatus  n.  sp.mj*  5-*  :  5J  6.5  "*•  5.9  '  Striae  of  the 
naked  cuticle  resolvable  into  rows  of  dots,  which  are  modified  a  little  on  the 
lateral  fields,  where  there  are  distinguishable  two  longitudinal  rows  of  markings 
close  together  on  each  side  of  the  lateral  line,  at  least  toward  the  anterior  extrem- 
ity and  on  the  neck.  The  neck  is  cylindroid.  There  are  probably  four  or  six 
short  and  inconspicuous  cephalic  setae  in  the  midst  of  the  labial  constriction. 
There  are  twelve  lips  of  the  character  usually  found  in  the  genus  Cyatholaimus, 
but  smaller,  and  in  such  a  position  in  the  specimen  examined  that  it  is  impos- 
sible to  make  out  the  details,  except  that  when  the  mouth  is  open  about  twelve 
papilla-like  lips  of  small  size  are  to  be  seen  toward  the  margin  of  the  head. 
Behind  the  pharyngeal  bulb  the  oesophagus  is  about  one-half  as  wide  as  the 
base  of  the  head.  It  continues  to  have  this  diameter  until  after  it  passes  through 
Ub  _  M  Hi  the  nerve-ring,  when  it  expands  to  form  the  pyriform  cardiac 

bulb,  which  contains  a  distinct  but  simple  valvular  apparatus. 

The  intestine  joins  the  middle  of  the  posterior  surface  of  the 

3~~fjgK3r  /«  cardiac  bulb,  and  is  at  that  point  only  about  one-fourth  as  wide 
g|l  Qg  as  the  base  of  the  neck;  it  gradually  widens  out  so  as  to  become 
half  as  wide  as  the  body.     It  would  present  few  cells  in  cross- 
750  section,  perhaps  only  two.    The  renette  cell  is  about  one-third 
as  wide  as  the  body,  and  fully  twice  as  long  as  wide,  and  lies  a  short  distance 
behind  the  base  of  the  neck.    The  tail  of  the  male  is  conoid  in  the  anterior  three- 
fourths;  thence  onward  it  tapers  more  rapidly  to  the  minute  spinneret.     The 
posterior  fourth  of  the  tail  is  more  finely  striated  than  the  remainder.     Caudal 
setae  few,  minute,  and  scattered.    The  proximal  ends  of  the  uniform  spicula  are 
bent  over  toward  the  ventral  side  of  the  body.     The  spicula  are  of  very  peculiar 
form,  the  proximal  halves  being  much  more  strongly  arcuate  than  the  distal 
halves.    At  the  distal  extremity  each  spiculum  is  bifurcated,   one  fork,   the 
anterior,  being  rudimentary,  while  the  other,  the  posterior,  is  somewhat  S-shaped 
and  acute  distally.    The  finger-shaped  apophysis  of  the  accessory  extends  back- 
ward nearly  parallel  to  the  body-axis.     The  apophysis  is  nearly  as  strongly  cutin- 
ized as  the  spicula  themselves,  and  has  a  length  nearly  equal  to  that  of  the  anal 
body-diameter.    The  apophysis  is  nearly  twice  as  wide  as  the  spicula,  which 
have  a  width  about  equal  to  that  of  three  of  the  adjacent  annules  of  the  cuticle. 
Ejaculatory  duct  about  one-third  as  wide  as  the  body;  vas  deferens  about  half. 
Habitat:  Punta  Arenas,  Pacific  coast  of  Costa  Rica.     Marine.     Fig.  115. 


PTYCHOLAIMELLTJS  337 

116.  Ptycholaimellus  carinatus  n.  sp.  Cuticle  rather  thin  and  naked,  resolvable 
near  the  anterior  extremity  into  elements  which  are  interrupted  on  the  lateral 
fields.  Near  the  middle  of  the  body,  the  division  line  between  the  annules  is 
resolvable  into  dotlike  elements;  these  are  interrupted  by  two  prominent  lateral 
wings.  These  wings  begin  near  the  head  and  end  behind  the  middle  of  the  tail, 
and  near  the  middle  of  the  body  occupy  a  space  about  equal  to  the  width  of  one 
of  the  annules.  l-9__8^  •  j.5.5  "'49."  90. 
Neck  conoid ;  A3  ^  '  ~«  ~  ~  *-3~  "  ~2l>  L 

£.£?  Td  #-^±V-3S~-  — .  .  .  .^•£;.:.-, 
connected  with  the  anterior  margin  of  the  cer- 
vical cuticle  by  a  thin,  flexible  membrane. 
When  the  mouth  is  closed,  it  is  surrounded  by 
twelve  folds  in  the  lip-region,  which  come 
together  and  form  a  striated,  somewhat  tubu- 
lar vestibule,  having  a  length  about  equal  to 
the  width  of  two  of  the  adjacent  annules  of  the 
cuticle.  The  lip-region  stains  strongly  with 
carmine,  and  is  a  very  striking  feature  in 
stained  specimens.  The  lips  arch  together  V1  ^  :;-:m'f:  nX  750 

over  the  somewhat  spheroidal  anterior  portion  of  the  pharynx,  which  is  about 
one-third  as  wide  as  the  front  of  the  head  and  contains  the  strongly  cutinized 
apex  of  the  massive  dorsal  onchium,  which  has,  passing  backward  from  it,  dis- 
tinct refractive  extensions  that  gradually  merge  into  the  structures  of  the  oesoph- 
agus. The  narrow  portion  of  the  pharynx  merges  gradually  into  the  lumen  of 
the  oesophagus.  The  pharyngeal  swelling  contains  special  muscles  for  the  oper- 
ation of  the  lips  and  dorsal  onchium;  these  are  much  more  strongly  developed 
on  the  dorsal  side,  and  the  pharyngeal  swelling  presents  the  peculiarity  of  being 
widest  near  its  anterior  part,  and  tapering  gradually  nearly  half  way  to  the  nerve- 
ring,  where  the  diameter  has  been  so  reduced  as  to  be  one-third  that  of  the 
corresponding  portion  of  the  neck.  The  oesophagus  continues  to  have  this  width 
until  after  it  passes  through  the  nerve-ring,  where  it  enlarges  rather  gradually 
for  a  short  distance,  and  then  more  rapidly  to  form  the  clavate,  or  elongated- 
pyriform,  strongly  developed  cardiac  bulb,  which  occupies  the  posterior  three- 
sevenths  of  the  neck,  and  becomes  three-fourths  as  wide  as  the  base  of  the  neck. 
This  bulb  is  divided  into  two  approximately  equal  parts  by  a  transverse  division 
of  the  musculature  and  its  valvular  apparatus  is  correspondingly  divided.  This 
latter  consists  essentially  in  a  plain  expansion  of  the  lining  of  the  oesophagus, 
which  is  in  its  widest  part,  about  one-third  as  wide  as  the  bulb.  There  is  no  dis- 
tinct cardia.  The  intestine  joins  the  middle  of  the  posterior  surface  of  the  car- 
diac bulb,  and  at  this  point  is  only  one-fifth  as  wide  as  the  neck.  It  gradually 
widens  out  so  as  to  become  half  as  wide  as  the  body  and  then  diminishes  again 
to  give  place  to  the  enormously  developed  renette  cell,  behind  which  it  again 
becomes  about  half  as  wide  as  the  body.  The  intestine  is  rather  thin-walled,  its 
cross-section  presenting  about  four  to  six  cells  containing  scattered  yellowish 
granules  of  variable  size,  the  largest  of  which  have  a  diameter  nearly  as  great  as 
the  width  of  one  of  the  adjacent  annules  of  the  cuticle.  From  the  slightly  raised 
anus,  the  rectum  extends  inward  a  distance  equal  to  the  anal  body  diameter. 
The  lateral  fields  are  fully  one-third  as  wide  as  the  body.  The  renette  cell,  two- 
thirds  to  three-fourths  as  long  as  the  neck,  is  clavate,  and  at  its  widest  part  half 


338  ORDER   ANAXONCHIA 

as  wide  as  the  body.  It  contains  a  single  nucleus,  which  is  swung  centrally  in 
the  protoplasmic  network.  The  renette  cell  has  two  spherical  ellipsoidal  com- 
panion cells  in  the  rear.  The  excretory  pore  lies  at  the  base  of  the  lips,  and  is 
connected  with  the  elongated,  fusiform  ampulla  by  means  of  a  duct  which  extends 
from  the  base  of  the  lips  to  nearly  opposite  the  base  of  the  pharynx.  Some- 
times the  ampulla  is  much  elongated,  and  one-fourth  as  wide  as  the  corresponding 
portion  of  the  neck,  reaching  nearly  to  the  nerve-ring.  The  tail  begins  to  taper 
from  far  in  front  of  the  anus,  and  tapers  at  about  the  same  rate  for  some  little 
distance  behind  the  anus,  then  tapers  more  rapidly  for  a  short  distance,  and 
then  finally  tapers  gradually  to  the  terminus.  The  caudal  glands  are  located 
in  the  base  of  the  tail.  The  vulva  is  massive  and  yet  does  not  project  much 
beyond  the  main  ventral  contour.  It  is  prominent  on  account  of  a  depression 
which  surrounds  it.  From  the  vulva  the  large  vagina  leads  inward  half  way 
across  the  body.  The  tapering,  reflexed  ovaries  reach  half  way  back  to  the  vulva 
and  contain  upwards  of  ten  ova  arranged  single  file.  The  prolate  eggs  are  nearly 
as  long  as  the  body  is  wide  and  have  been  seen  in  the  uterus  one  at  a  time.  The 
distance  between  the  wings  on  the  cuticle,  near  the  anus  of  the  male,  is  about 
equal  to  the  width  of  two  of  the  annules.  The  tapering,  yellowish  spicula  are 
more  strongly  arcuate  in  their  proximal  halves  than  elsewhere.  At  their  widest 
part  they  are  about  one-sixth  as  wide  as  the  corresponding  portion  of  the  body. 
Their  proximal  ends,  when  viewed  laterally,  appear  to  lie  opposite  the  body- 
axis.  An  indistinct  refractive  line  passes  from  the  proximal  ends  of  the  spicula 
to  the  distal  ends,  indicating  that  the  spicula  may  be  wider  than  would  be  judged 
by  a  consideration  of  only  the  main  portion  of  their  framework.  The  accessory 
pieces  are  one-half  as  long  as  the  spicula  and  in  the  main  parallel  to  them  and 
are  arranged  in  comparatively  close  contact.  Near  the  anus,  however,  the  frame- 
work of  the  accessory  pieces  bends  away  from  the  spicula.  Each  accessory  piece 
ends  in  an  acute  protrusile  point,  which  is  rather  suddenly  and  rather  markedly 
bent  forward.  The  spicula  present  the  same  arcuate  appearances  at  their  tips 
as  do  the  accessory  pieces.  Both  the  ejaculatory  duct  and  vas  deferens  are  about 
one-third  as  wide  as  the  corresponding  portion  of  the  body. 

Habitat:  Larat,  East  Indies.  Marine;  apparently  very  common.  Sublimate 
to  balsam.  Fig.  116,  p.  337.  An  examination  of  sloughed  cuticle  of  the  head 
gave  equally  satisfactory  evidence  of  the  existence  of  joints  in  the  setae. 

117.  Actinonema  pachydermatum  n.  sp.  Cuticle  naked,  very  thick,  occupying 
one-half  the  radius  as  measured  at  the  base  of  the  neck.  Annules  alike  except 

-35  8.6  -it__  _V1L_?i'_>  83  .  tnat  tney  grow  narrower  toward 
T8~~ir~3Tj  4.«  2-5  '  ""  the  extremities,  especially  the  head 
.35  9.z  _i6.  -x  85.  end;  resolvable  with  difficulty  into 

T.~~i.l~7.7  M^S,*!"  *S"  rod-like  markings,— with  less  diffi- 
culty on  the  anterior  half  of  the  body.  The  prominent  wings,  begin- 
ning  on  the  neck,  end  near  the  middle  of  the  tail.  As  there  are  deep, 
narrow  grooves  between  the  annules,  the  contour  of  the  body  is  irreg- 
ularly crenate.  Head  set  off  by  contraction  and  a  deep  constric- 
tion, subtruncate ;  mouth  more  or  less  depressed.  The  lip-region  is  one-half  as  high 
as  wide,  and  appears  to  be  composed  of  three  fairly  well  developed,  rounded,  sub- 
distinct  lips,  which  are  set  off  by  constriction.  This  lip-region  appears  as  if 
protruding  from  within  the  thick  cuticle,  and  stains  in  carmine  while  the  cuticle 
remains  quite  colorless.  On  the  lips  there  are  no  obvious  signs  of  a  cuticle.  The 


ACTINONEMA,    RHIPS  339 

pharynx  is  very  small  and  inconspicuous,  or  even  absent  apparently.  There  seems 
to  exist,  however,  a  minute,  more  or  less  arcuate  dorsal  onchium,  to  be  seen  in 
balsam  specimens  only  when  -exserted.  The  neck  is  conoid,  the  head  convex- 
conoid.  Amphids  nearly  straight  transverse  slits,  four-fifths  as  long  as  the 
corresponding  diameter  of  the  head,  and  apparently  eight  times  as  long  as  wide. 
One  of  the  foremost  annules  appears  to  be  more  or  less  dislocated;— that  is  to 
say,  the  regular  succession  of  the  fore-most  annules  is  somewhat  disturbed  by 
X?50  \>\  SP  ^ne  Presence  °f  the  amphids,  which  are  otherwise  almost 

invisible.  Oesophagus  more  or  less  conoid,  but  decidedly 
clavate  posteriorly.  Near  the  head  it  is  two-fifths,  near 
the  nerve-ring  about  one-fourth,  and  finally  one-half,  as 
wide  as  the  corresponding  portion  of  the  neck.  There  is 
no  distinct  cardia.  The  rather  thin-walled  intestine,  which 
becomes  at  once  two-fifths  as  wide  as  the  body,  has  a  dis- 
tinct lumen.  Its  cross-section  presents  four  to  six  cells. 
Cardiac  collum  one-fifth  as  wide  as  the  body.  From  the 
depressed  anus  the  prominent  cutinized  rectum  is  one  and 
one-fourth  times  as  long  as  the  anal  body-diameter.  The 
cells  of  the  intestine  contain  numerous,  very  fine,  colorless  granules.  The  co- 
noid, subarcuate  tail  tapers  from  in  front  of  the  anus  to  the  simple,  unarmed,  con- 
vex-conoid, rather  blunt  spinneret.  The  ellipsoidal  caudal  glands  are  small 
and  inconspicuous,  more  or  less  unsymmetrical,  and  apparently  lie  in  a  close  tan- 
dem opposite  the  anus.  The  elongated  to  fusiform,  granular  renette  cell  lies 
behind  the  neck  a  distance  equal  to  one  and  one-half  body-diameters;  it  is  as 
long  as  the  body  is  wide  and  one-fifth  as  wide  as  long.  Female  sexual  organs 
double.  The  tapering  ovaries  are  of  moderate  size  and  extend  half  way  back  to 
the  vulva.  They  contain  few  ova  arranged  for  the  most  part  single  file.  The 
simple,  strong,  tapering,  rather  stout  spicula  are  at  their  widest  part  about  one- 
sixth  as  wide  as  long.  Their  proximal  ends  appear  to  lie  more  or  less  opposite 
the  body-axis.  The  simple,  rather  frail,  slender  accessory  piece  is  about  two- 
thirds  as  long  as  the  spicula.  There  are  no  supplements  or  special  papillae. 
Habitat:  "Seagrass,"  shoal,  two  miles  off  Key  West,  Florida,  U.  S.  A.  Fig.  117. 


118.  Rhips  ornata  n.  sp.  1.3  i.i/~  2~._6. 3-  1.9  '  "  Cuticle  thick,  contour 
more  or  less  crenate.  Striae  resolvable  into  rod-like  markings,  ygf//n/  ._  ppl(l)l 
changing  so  as  to  produce  a  basketwork-like  effect  on  the  neck. 
On  the  posterior  half  of  the  body  on  each  lateral  field  each 
annule  presents  two  forward-pointing,  "V  "-shaped  marks  of 
unequal  size,  the  ventral  being  the  larger;  these  are  inconspicu- 
ous, but  are  less  so  posteriorly.  These  markings  occur  also  on 
the  anterior  half  of  the  body,  but  are  there  reversed.  On  a  par 
with  the  celphalic  setae,  and  just  in  front  of  the  ends  of  the 
amphids,  there  are  four  sublateral,  special  scales,  or  short, 
more  or  less  conical  horns,  about  half  as  long  as  the  setae,  (ppl  Fig.  118a.)- 
What  function  is  associated  with  these  peculiar  appendages  is  unknown.  Lips 
very  minute,  apparently  six  and  double.  The  neck  has  the  peculiarity  of  dimin- 
ishing more  rapidly  from  the  middle  forward  for  a  short  distance.  The  dorsal 
onchium  is  opposed  by  one  or  two  very  minute  ventrally  submedian  ones.  The 
oesophagus  is  conoid,  though  there  is  a  more  or  less  pronounced  clavate  cardiac 
swelling.  At  the  nerve-ring,  the  oesophagus  is  one-half,  and  finally  three-fourths, 


340 


ORDER   AXAXOXCHIA 


as  wide  as  the  corresponding  portion  of  the  neck.     The  rather  prominent  lining 
of  the  oesophagus  finds  expression  in  about  three  parallel  refractive  lines,  occu- 


pying a  space  equal  to  two-fifths  its  width.  The 
fine  musculature  is  more  or  less  pigmented.  There 
is  a  decided  thickening  of  the  lining  in  the  cardiac 
swelling.  There  is  no  cardia.  The  thin-walled 
intestine  presents  a  faint  lumen,  and  becomes  at 
once  three-fifths  as  wide  as  the  body.  Cardiac  col- 
lum  one-fourth  as  wide  as  the  neck.  From  the 
more  or  less  continuous  anus,  the  inconspicuous 
rectum  leads  inward  a  distance  one  and  one-fourth 
times  as  great  as  the  anal  body-diameter.  The 
postanal  region  has  the  appearance  of  lacking  one 
of  the  regular  striae.  Colorless  granules  of  vari- 
able size  are  scattered  in  the  intestinal  cells.  The 
largest  of  them  are  about  half  as  wide  as  one  of  the 
annules.  The  conoid,  subarcuate  tail  tapers  from 
in  front  of  the  anus  to  the  convex-conoid  spinneret. 
Apparently,  the  caudal  glands  lie  in  the  anterior 
third  of  the  tail.  Though  the  renette  has  not  been 
clearly  seen,  it  appears  to  lie  two  body-widths 
behind  the  neck,  to  be  elongated  and  twice  as  long 
as  the  body  is  wide.  The  large,  elevated,  conspic- 
uous vulva,  occupying  twenty-five  to  thirty  annules 


sutait 


X7 


of  the  cuticle,  leads  to  a  medium-sized  vagina.  The  female  sexual  organs  are 
double  and  symmetrically  reflexed.  The  eggs  are  probably  rather  large,  since 
an  ovum  which  has  not  yet  entered  the  uterus,  but  appears  to  be  mature,  is 
three  times  as  long  as  the  body  is  wide.  Spherical,  granular  spermatozoa, 
.9  7-5  .  i*.  _  -x"  90.  one-half  as  wide  as  the 

-1:2"- ."T"i:-  "     body,   were  seen  in  the 

uterus.  Spicula  two-jointed,  as  shown  in  the  illus- 
tration. A  mature  specimen  was  seen  in  which  the 
spicula  were  lacking,  suggesting  that  possibly  they 
are  Tost  at  the  time  of  copulation.  See  adjacent  illustra- 
tion. Accessory  pieces,  two  in  front  of  the  spicula  and 
two  behind,  with  an  additional  median  one  behind,— 
that  is  to  say,  five  in  all.  The  ventral,  longitudinal  opti- 
cal section,  about  twenty-five  annules  in  front  of  the 
anus,  is  such  that  the  subcuticle  appears  more  or  less  as 
if  retrorsely  serrate.  This  alteration  in  the  annules  is 

co-extensive  with  the  oblique  copulatory  muscles,  so  that  no  doubt  these  struc- 
tures must  be  regarded  as  indicating  the  presence  of  supplementary  organs. 

Habitat:  Marine  mud,  Ocean  Beach,  Florida,  U.  S.  A.    Fig.   118a,  p.  339; 
Figs.  1186  and  c. 


X750 


ABBREVIATIONS  USED  IN  ILLUSTRATIONS 

Frequently  the  abbreviations  are  combined,  thus:  set  trm,  seta  terminalis,  terminal  hair;  set  vph 
dxt  subl,  seta  cephalicadextra.  sublateralis,  right  sublateral  cephalic  seta. 


Ac,  accessory 
af,  afferent 
al,  wing 

fr,  front,  frontal 
frt,  fertile,  fertilized 
furc,  furcation,  forked 

post,  posterior 
pp,  ppl,  papilla,  papillate 
prerct,  prerectum 

amp,  ampulla 

prm,  primary,  first 

amph,  amphid 
an,  anus,  anal 
anak,  anakinesis,  anaphase 

Gam,  gamete 
gl,  gland,  glandular 
glot,  glottis,  glottoid 

•prok,  prokinesis,  prophase 
prtph,  protophyte 
prtz,  protozoon 

ann,  annule 

gub,  gubernaculum,  guide,  ac- 

prx, proxima,  proximal 

ant,  anterior 

cessory  piece 

pseudon,  pseudonchium 

anus,  anus 

gnd,  gonad 

punct,  point,  bead,  dot 

apic,  apiculum 

gng,  ganglion 

pyl,  pylorus,  pyloric 

apnd,  appendage 
apph,  apophysis 
or,  area,  field 

grn,  granule,  granular 
Tm,  immature 

Rack,  rachis,  axial  strand 
rcpt,  receptacle,  sack 

asp,  aspect,  view 

^-  ing,  ingested 

ret,  rectum,  rectal 

ast,  aster 

int,  intestine,  intestinal 

red,  reduction,  reduced 

axil,  axil,  axillary 

intnl,  internal,  inner 

reg,  region 

ax,  axis,  axis 

intr,  interior 

rem,  lost,  discarded 

ren,  renette,  ventral  gland 

1>as,  base 
•O  birefr,  birefringent 
bib,  bulb,  bulbous 

Tnc,  junction,  junctional 

res,  resv,  reservoir 
ret,  reticulum,  reticular 

brs,  bursa,  bursal 

Kar,  karyokinetic  figure 

rtr,  retrorse,  reversed 

fal,  lime,  calcareous 
*-*  cav,  cavity 

rtrct,  retractor,  retracting 
rud,  rudiment,  rudimentary 

cd,  cdl,  tail,  caudal 
cer,  ceratin,  ceratinous 

*-*     lac,  lacuna,  pit,  depression 
lam,  lamina,  plate,  laminate 

Sal,  saliva,  salivary 
sb,  sub 

cere,  cervical 
chrm,  color,  chromatio 
chrmt,  chromatin 
chrsm,  chromosome 
chrt,  chromatin 
cir,  cirrus,  cirri     * 
cl,  cell,  cellular 
clc,  cloaca,  cloacal 
dv,  cleavage,  cleft 

lat,  lateral,  laterad 
Ib,  lip,  labial 
Ins,  lens  (of  eye) 
lob,  lobe,  lobate 
longt,  longitudinal 
In,  larva,  larval 
Ingt  sec,  longitudinal  section 
lum,  lumen,  luminal 

sc,  scale,  scaly 
sec,  section,  cross-section 
secnd,  second,  secondary 
se(7,  segment,  segmented 
sem,  semen,  seminal 
set,  seta,  setaceous 
snst,  left,  left-hand 
som,  soma,  body,  somatio 

cntr,  centrosome 
col,  collum,  constriction 
com,  commissure 
comp,  companion 
constr,  constriction 
cop,  copulatory 
corp,  body,  thing,  corpus 
cost,  costa,  rib,  costal 
cph,  cephalum,  cephalic 
cpl,  hair,  capillary 
crd,  cardia,  cardiac 
crib,  sieve,  mesh 
crp,  corpus,  body,  thing 
en,  neck,  cervical    . 
cryst,  crystal,  crystalline 

Ma/,  major,  the  larger 
mat,  mature 
marg,  margin,  edge,  marginal 
md,  middle,  median 
mesok,  mesokinesis,  mesophase 
metak,  metakinesis,  metaphase 
micrph,  microphyte 
micrz,  microzoon 
min,  minor,  the  lesser 
mit,  mitosis,  mitosis-figure 
mnd,  mandible,  jaw,  mandibula 
monast,  monaster 
msc,  muscle,  muscular 
mur,  wall,  mural 

sp,  spiculum,  spicula 
sphnc,  sphincter 
spir,  spireme,  spiral 
spm,  sperm,  spermatozoa 
spmct,  spermatocyte 
spmtd,  spermatid 
spn,  spinneret 
spndl,  spindle 
spthc,  spermatheca 
sq,  scale,  squamule 
st,  stoma,  mouth,  pore 
str,  stria,  striated 
sub.  sub,  nearly,  almost 
subd.  subdorsal 
subl,  sublateral 
subm,  submedian 

cut,  cuticle,  cuticular 
cutn,  cutin,  cutinous 
cytp,  cytoplasm 

N  nerve 
ncl,  nucleus,  nuclear 
nema,  nema,  nematode 
n  r,  nerve-ring 

subst,  substance,  matter 
subv,  subventral 
sup,  supplement,  supplementary 
sut,  suture 

T-|C<,  duct 

•"-*  dep,  deposit,  deposited 

nud,  naked 

rpfc,  tube,  tubular 

diast,  diaster 

•*•    teg,  shell,  tegument 

dir,  directrix,  guide 
dnt,  tooth,  dental 

f\c,  eye,  ocular 
"  oe,  oesophagus,  oesophageal 

telek,  telekinesis,  telephase 
tesl,  tessellation 

dntcl,  denticle,  little  tooth 
dsc,  disc,  discoid 

on,  onchium,  tooth,  spear 
onch,  onchium,  spear,  onchial 

trans,  transverse 
trm,  end,  blind  end,  terminal 

dsl,  dorsal,  dorsad 

ocyt,  oocyte 

ttrd,  tetrad,  four-fold 

dst,  distal,  far,  farther 

or,  mouth,  oral 

turn,  tumor,  swelling,  swollen 

dxt,  right,  right-hand 

org,  organ 
orgf,  organ  in  doubt,  doubtful 

Ut,  uterus,  uterine 

IT1/,  efferent 

os,  ostium 

•*-'  elast,  elastic  spring,  springy 

or,  ovum,  egg 

elev,  elevation 

our,  ovary,  ovarian 

V  vessel 

elmt,  element,  component 
emb,  embryo,  embryonic 

Ppor,  pore 

'       vag,  vagina,  vaginal 
valv,  valve,  valvular 

eg,  equator,  equatorial 
ex,  excreta,  excretory 
ex  p,  excretory  pore 

par,  parasite,  parasitic 
pet,  pectoral 
pclr,  peculiar,  remarkable 

DOS,  vessel 
ras  def,  v  def,  vas  deferens 
vesic,  vesicle,  vesicular 

extn,  extension,  extended 

pgm,  pigment,  pigmented 

vlv,  vulva 

extnl,  external 

ph,  pharynx,  pharyngeal 

vnt,  ventral,  ventrad 

extr,  exterior,  outer 

phs,  phase,  state,  condition 
pigm,  pigment,  pigmented 

vst,  vestige,  vestigial 
nstbl,  vestibule,  vestibular 

"CVjfe,  fb,  framework 

pip,  palp 

vstg,  vestige,  vestigial 

"  fasc,  fascicle 

plr,  polar 

fibr,  fibre,  fibrous 

pnct,  point,  dot,  punctate 

Zon,  zone,  zonal 

fix,  flexure 

par,  pore 

341 


INDEX 


Acanthonchus 

page 

...  321 

cephalata 
Pseudolella  

page 

...  268 

fissidens 
Daptonema  

page 

acanthurum 
Zanema  
Actinonema 

...  283 
...  338 

Xennella  
cephalatum 
Micromicron  
Cephalobellus 

...  233 

...  324 

flexile 
Cyartonema  
Rhadinema  
fontinalis 

.  242 
.  256 

245 

Colpurella 

257 

...  308 

acuta 

329 

microbivorum  

...  270 

Crystallonema  

.  282 

i 

264 

Gammanema 

...  234 

Chambersiella 

ferox  

.  291 

aequalis 

250 

rodens  

...  278 

glabra 
Asymmetrella  

.  287 

Alaimella 

simplex  

...238 

Gonionchus 

315 

cincta  

234 

Alaimella 

233 

granulifera 

Leptonemella  

...244 

Pseudolella  

.  268 

multicinctum  
americanum 

...  327 
252 

Cinctonema 
tenue  

...  244 

granulosus 
Leptonchus  
guttata 

.  304 

Amphispira 
rotundicephala  
amplicolle 

...  324 
...  305 

Croconema  
Rhynchonema  
Coinonema 

...  332 
...  260 

...  259 

Trilepta  
guttatus 
Nannolaimus  

.  312 
.  255 

Anaxonchium 

.  319 

Colpurella 
fontinalis 

257 

macrurus  

.  266 

Anoncholaimus 
mobilis  
Anticyatbus 

...  312 
245 

Cophonchus 
ocellatus  
Croconema 

...328 
332 

spinosum  
heterurus 
Myolaimus  

.  267 
.  274 

Anticyclus 
exilis.  

...331 

Crystallonema 
fuscacephalum  

...  282 
...  283 

Hyalaimus 
brevicollis  

.  238 

241 

exile 

261 

flexile                   

.     242 

mollis.  

...301 

cylindricolle 

...  298 

lotonchium  

.  302 

...  277 

cylindricollis 

r^mnvlaimus 

232 

Aponchium 

..298 

Mesodorus  

...  325 

lonema 

235 

Asymmetrella 
glabra           

...  287 

Triplonchium  

...  SCO 

lotadorus 

336 

i     if        is 

262 

T   t   1    ' 

Cpramonema 

264 

P   t   1    'miiiTn 

lotaiaiinus 

239 

251 

s  triatus  

Protrellus  
Axonchium 

...  256 
305 

"rvactylaimus 
JLJ    aequalis 

250 

imperfectum  (Butschli) 
Ironella 

.    302 
277 

-plattophila 

Daptonema 
fimbriatum  

fissidens 

...  282 
...  281 

Isolaimium 
papillatum  

.  258 

•*-*    sphaerolaima  
Bolbella 

....  271 
308 

Dasynema 
sexalineatum  

...  253 

acuta  

.  329 

Bolbinium 
brevicolle  
Bolbolaimus 

....  240 

demonstrans 
Campydora  
Didelta 

...  307 

longicauda  
Laxonema 

.  261 
?43 

...  319 

maj  i 

punctatus  

....  321 

314 

pellucfda  

.  249 

Bolbonema 

....  264 

Dorylaimus  Dujardin 

Leptonchus 

304 

braziliense 
Synonema  

brevicolle 

....  330 
...240 

Doryllium 
uniforme  

...  303 

Leptonemella 
cincta  
lineata 

..  244 
334 

Bolbonema  
Stilbonema  

....  264 
....  242 

Catanema  

...  271 
251 

Linhomoella 
exilis          

254 

brevicollis 

'  Illium  

...  261 

Litinium 

Polylaimium  
Ypsilon  

...  274 
...  314 

aequale  
Litonema 

237 

^    demonstrans  
Campylaimus 

....  307 
232 

Anticyclus  
Linhomoella  
Schistodera 

...331 

...  254 
231 

litorium 
Anaxonchium  
Omicronema  

,.  319 

carcinicolum  (Baylis) 
Tripylium  
carinatus 
Ptycholaimellus  

....  288 
....  337 

.fecundum 
1    Synodontium  
ferox 

...  280 

Litotes 
minuta  
longicauda 
Laimella  

..  230 
..  261 

Catalaimus 
acuminatus  
Catanema 
exile... 

....  308 
...  271 

Gammanema  
Thoonchus  
fimbriatum 
Daptonema  

...  291 
...  310 

...  282 

longicaudatus 
Onchulus  
longicollis 
Dorylaimus  Dujardin.  . 

.  313 
..  306 

342 


INDEX 


343 


ryiacrurum 
Rhabdocoma.... 

page 
252 

pacificum 
Apodontium  
papillatum 

page 

277 
258 

spinosum 

page 

macrurus 
Halanonchus  
maculatum 
Didelta  

266 
252 

Stilbonema 
brevicolle  
striata 

...  242 

papilliger 
Cephalobellus  
pellucida 

245 
249 

majutn 
Laxonema  
Margonema 
ringens  

243 
248 

Xyala 

...  289 
...  247 

Zygonemella  
striatus 

pellucidum 
Antomicron  
Pepsonema  
pellucidus 
Bolbolaimus  
Myctolaimus  
Pepsonema 
pellucidum  
perfectum 
Xinema  
Polylaimium 
exile  

241 
295 

319 
276 

295 
263 
274 

Mesodorus 
cylindricollis  
Mesonchium 

325 
294 

...  250 
.  .  .  280 
...  290 
...330 

Synodontium 
fecundum  
Synonchium 
obtusum  
Synonema 
braziliense  

microbivorum 
Cephalobium  

270 

minuta 
Litotes  
mobilis 

230 
312 

4-enue 
L    Cinctonema  
tenuicaudatus 
Anticyathus  
tenuidens 
Bolbella  
Thoonchus 
f  erox  
transitans 
Monhystrium  
Trilepta 
guttata  

cylindricum  
Tripylium 
carcinicolum  (Baylis)  .  , 
Trissonchulus 
oceanus  
Trogolaimus 
uniformis  
truncata 
Alaimella  
Tycnodora 

...  244 
.  .  .  245 
...  308 
...  310 
...284 
...312 
...300 
.  .  288 
...  297 
...  293 
...  234 
231 

Polysigma 

326 

mollis 
Aphelenchulus  
Monhystrium 
transitans  
wilsoni  
multicinctum 
Alaimonema  
Myctolaimus 
pellucidus 

301 

...  284 
285 

327 
276 

poriferum 
Mesonchium  
Porocoma 
striata 

.....  294 
236 

prismatolaima 
Ironella  
Protrellus 

277 
256 

Pseudolella 
cephalata  
granulifera  
Pseudonchus 
rotundicephalus  
Ptycholaimellus 
carinatus  
punctatum 
Coinonema  
punctatus 
Bolbolaimus  
punctulatus 
lotadorus  
Pycnolaimus 
pygmaeus  
pygmaeus 
Pycnolaimus  

•petrorsum 
Rhinema  
Rhabdocoma 

...  268 
268 

273 
337 
259 
321 
336 
258 
258 

335 
252 

Myolaimus 
heterurus  

Nannolaimus 
guttatus  
Nemanema 
simplex  
Nemella 
ocellata  
Neurella  ' 
simplex  
nuda 

274 

255 
230 
236 
246 
317 

iiniforme 
Doryllium  

...  303 
...  326 

...  262 
...  314 
...  293 

...  315 
...  321 

...  285 

...  317 
233 

Nudora 
lineata  
nudum 
Litonema  
Zalonema  

Obesum 
Xenonema  
obtusum 
Synonchium  
oceanus 
Trissonchulus  
ocellata 
Nemella  
Onchulella  
ocellatum 

Onchium  
ocellatus 
Cophonchus  
Omicronema 
litorium    
Onchium 
ocellatum  
Onchulella 
ocellata  
Onchulus 
longicaudatus  
ornata 
Rhips 

334 

...  237 
272 

323 
290 
297 

.....  236 
.  .  .      306 

235 
303 

328 
265 
303 
306 
313 
339 

uniformis 
Cynura  
Digitonchus  
Trogolaimus  

Villosus 
Gomonchus  
viviparus 
Acanthonchus  

Wilsoni 
Monhystrium.  .  .  . 

Xanthodora 
nuda  
Xennella 

macrurum  
Rhadinema 
flexile 

252 
256 

Rhinema 
retrorsum  
Rhips 

335 
339 

Rhynchonema 
cinctum  
ringens 
Margonema  
rodens 
Chambersiella  
rotundicephala 
Amphispira  
rotundicephalus 
Pseudonchus  

Schistodera 
exilis  
sexalineatum 
Dasynema  
simile 
Crystallonema  
simplex 
Choronema  
Nemanema  
Neurella  
sphaerolaima 
Blattophila  

260 
248 
278 
324 
273 

231 
253 
283 

238 
230 
246 

271 

Xenolaimus 
striatus  
Xenonema 
obesum  
Xinema 
perfectum  
Xyala 

...250 
...  323 
...  263 
289 

Vpsilon 
i     exile  

..  314 

.  272 
283 

^alonema 
t*    nudum  
Zanema 

rjachydermata 
"    Tycnodora  
pachydermatum 
Actinonema  

231 
338 

Zygonemella 
striata  

..  247 

HOWARDULA  BENIGNA 

A  nemic  parasite  of  the  Cucumber-beetle,  (Diabrotica) 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  X 

BY  N.  A.  COBB 

Howardula  Cobb,  '21.  Characters  of  Tylenchus  Bastian,  1865,  but  without 
oesophageal  bulb  and  with  a  non-bulbous  onchium  and  much  reflexed  ovary. 
Female  finally  a  flaccid,  cylindroid  sack,  without  distinct  alimentary  canal,  and 
otherwise  very  much  deteriorated.  Amphigonic;  male,  free-living.  Howardula 
is  probably  related  to  Bradynema  zur  Strassen  1892.  The  latter  however  is 
anonchial,  and  even  lacks  a  mouth  opening. 

Howardula  benigna  Cobb,  '21.  i:i  (?)^  ....  (?)         <98-      (?)99-     3  5  c  BB 

2.5      ,4.0'"    4.7          4.1          L9 

Anus  none  or  vestigial;  vulva  sometimes  terminal;  uterus  nearly  filling  the 
body-cavity,  posteriorly  packed  with  larvae  and  ante- 
riorly with  segmenting  eggs,  near  the  head  in  the  vicinity 
of  the  small  spermatheca  narrowed  and  reflexed  to  the 
middle  of  the  body,  whence  the  narrow  ovary  turns  for- 
ward and  ends  blind  near  the  head;  onchium  of  adult 
obscure  but  the  minute  mouth  opening  still  persisting. 
Inert,  viviparous,  usually  all  of  about  the  same  stage  of 
development  in  any  individual  host-insect,  each  when 
mature  containing  about  two  thousand  embryos  and  seg- 
menting eggs;  the  larvae,  of  two  kinds,  sometimes  ten 
to  twenty  thousand  of  them,  proceeding  from  the  mother 
nemas  into  the  body-cavity,  and  thence  into  the  sexual 
apparatus,  of  the  host,  and  so  becoming  deposited  with 
the  eggs  of  the  latter.  See  Figs.  3,  6  and  7. 

2.         16.    (?)24.       -95.      (?)97.     n  = 

Larval  formula : 0.5-™ 

2.        4X       5.  4.  2.6 

These  are  the  measurements  of  the  larvae  as  they  issue 

from  the  vulva.     Those  within  the  mother  nema  and  in 

the  anterior  part  of  the  uterus  are  considerably  shorter.     FHgitl 

Anus  none  or  vestigial;  tail  conoid,  straight,   broadly   ture  and 

rounded  or  subtruncate  at  the  terminus.     After  deposi- 

tion  along  with  the  beetle  eggs,  the  young  nemas  moult   ^^J^  actual  length  of 

with    little   increase  in   size;  after  mating,   the  female 

drills  into  the  body-cavity  of  even  very  young  beetle  larvae  of  both  sexes, 

sometimes  to  the  number  of  thirty,  but  more  often  five  or  six.    The  following 

Waverlv  Press.  Baltimore,  Md..  June  9.  1928.    Revised  and  continued  from  Nematology  X,  Aug.  8. 
1921,  Waverly  Press.    See  Science,  Dec.  30,  1921. 


346 


DISTRIBUTION    OF    HOWARDULA 


are  the  dimensions  and  other  details  of  these  young  but  already  spermatized 
individuals,  as  found  both  in  the  soil  and  in  very  young  beetle-larvae,  which 
in  the  body-cavity  of  the  host  reach  the  above  seven  to  ten  times  longer,  mature 

3.4  (?)12.         28.         -91.      (?-)94.8 
form:— — 7  0  :::::   7  7  ^         ^~7  0.54™ 


3.7 


2.8 


Fig.  2.  Map  showing  distribution  of  the  nema 
Howardula  benigna  as  disclosed  by  examinations  in 
1921  The  aim  was  to  examine  at  least  100  cucumber- 
beetles  from  each  locality.  This  aim  was  achieved 
in  most  cases.  The  map-figures  give  the  percentage 
of  beetles  found  infested  by  Howardula.  The  figures 
for  different  localities  a  few  miles  apart  in  any  given 
region  usually  were  in  substantial  agreement,  but  the 
figures  for  different  regions  varied  much.  Where  the 
percentage  of  infestation  was  highest,  the  nematism 
was  highest.  The  presence  of  the  nema  does  not 
exclude  other  internal  parasites,  such  as  other  insects 
and  gregarines.  Only  one  other  nemic  parasite  was 
observed,  represented  by  a  single  Nova  Scotian  speci- 
men. About  1500  D.  tittata  were  examined.  Below 
are  the  addresses  of  those  who  kindly  contribut  J 
insects  for  examination. 


Balduf,  W.  V.  Marietta,  O. 
Campbell,  R.  Alhambra,  Cal. 


Hall,  Dr.  M.  C.  Chevy  Chase,  Md.    Ross,  W.  A.  Vineland  Sta.,  Ont. 
Harned,  R.  W.  Agr.  College,  Miss.     Smith,  C.  E.  Baton  Rouge,  La. 

Thomas,  W.  A.  Chadbourn,  N.  C. 

Walters,  M.  J.  New  London,  Ct. 


Cobb,  Dr.  F.  Ann  Arbor,  Mich.  High,  M.  M.  Kingsville,  Texas. 
Cobb,  V.  Whitman,  Mass.  Kelsall,  A.  Annapolis  Royal,  N.  S. 

Centner,  L.  Lansing,  Mich. 


,     . 
Raps,  E.  M.  Oakton,  Va. 


Watson,  J.  R.  Birmingham,  Al. 


Habitat:  Common  in  the  body-cavity  (abdomen,  thorax  and  even  head)  of 
all  stages  of  Diabrotica  vittata,  trivittata,  and  12-punctata,  especially  the  two  for- 
mer, infesting  the  two  sexes  about  equally. 

My  attention  was  called  to  this  nema  by  Mr.  W.  V.  Balduf,  Assistant  Ento- 
mologist, Ohio  Agricultural  Experiment  Station,  Marietta,  Ohio,  where  he  dis- 
covered the  larvae  in  the  course  of  experiments  on  Diabrotica.  Owing  to  the 
economic  aspect  of  the  subject,  beetles  sent  me  by  Mr.  Balduf  were  exhibited, 
dissected,  at  the  Washington  Helminthological  Society's  meeting,  March  17, 
1921.  Examination  revealed  the  adult  female  form,  which  is  so  flaccid  and 
otherwise  deceptive  as  to  cause  it  rather  easily  to  be  confused  with  the  internal 
organs  of  the  host  by  one  not  already  versed  in  both  insect  and  nemic  anatomy. 
With  the  aid  of  Dr.  F.  H.  Chittenden  and  colleagues,  Federal  Bureau  of 
Entomology,  and  others,  the  geographical  distribution  of  the  nema  was 
studied  with  results  shown  on  the  accompanying  map,  which  indicates  that  the 
distribution  in  the  spring  and  summer  of  1921  was  probably  nearly  coextensive 
with  that  of  the  main  hosts,  Diabrotica  vittata  Fab.  and  trivittata  Mann.  The 
nematism  is  often  high  and  affects  on  the  average  about  20%  (0%-70%)  of  the 
insects.  Beetles  from  a  locality  where  they  are  not  nematized  are  larger,  brighter, 
more  vigorous.  Thus  twenty-five  beetles  from  an  uninfested  lot  were  much 


INTENSITY  AND  EFFECT  OF  THE  NEMATISM  347 

larger  and  averaged  seventy  per  cent  heavier  than  a  similarly  chosen  twenty-five 
from  a  fifty  per  cent  infested  lot.  Anatomical  evidence  shows  the  infested  female 
beetles  to  be  less  fertile  than  the  non-infested,  doubt  as  to  diminished  fecundity 
vanishing  where  the  female  host  harbors  a  dozen  or  more  adult  nemas.  In  such 
cases  the  mere  relative  volume  of  the  parasites  is  convincing  evidence  of  handi- 
cap. See  Fig.  1.  Mr.  Balduf  in  a  letter  speaks  of  beetles,  many  of  which  "died 
of  nemas."  I  have  no  rigid  proof  of  such  deaths,  but  believe  them  very  probable 
and  at  times  numerous.  Among  the  grubs  the  mortality  may  be  heavy. 

In  none  of  the  numerous  lots  of  beetles  examined  was  the  rate  of  infesta- 
tion by  any  other  zoo  parasite  as  high  as  by  Howardula,  with  the  single  excep- 
tion of  a  forty-three  per  cent  dipterous  infestation;  but  no  note  was  made  of 
degrees  of  phyto-infestation  (cucumber-wilt  organism,  etc.). 

As  many  as  thirteen  thousand  nemic  larvae,  by  count,  have  been  removed 
from  the  body-cavity  of  a  single  Diabrotica  vittata,  and  no  doubt  the  number 
may  go  much  higher.  On  several  occasions  twenty  or  more  adult  Howardulas 
were  taken  from  a  single  beetle.  Theoretically  these  should  produce  some  forty 
thousand  larvae  or  more.  The  older  female  beetles,  when  nematized,  deposit 
from  a  few  to  upwards  of  fifty  nemic  larvae  with  each  egg.  See  Fig.  3.  These 
soon  mature  on  the  eggs  or  in  the  soil  (where  they  can  live  several  weeks),  moult 
and  copulate,  the  female  developing  a  more  perfect  spear,  and  by  its  aid  drilling 
into  the  body-cavity  of  the  beetle  grubs  soon  after  the  latter  hatch  out.  See  Figs.  3 
and  4.  That  it  is  most  improbable  the  nemas  enter  the  host  by  way  of  the 
mouth  and  alimentary  canal  is  well  illustrated  in  Fig.  8.  The  active  young  beetle 
larvae  are  armed  with  sharp-toothed,  well  developed  mandibles.  That  the 
fragile  young  nemas  could,  in  any  considerable  numbers,  pass  so  relatively  small 
a  throat  and  mouth,  armed  as  the  latter  is,  one  hesitates  to  believe. 

In  plant-infesting  triplonchs  I  have  shown  the  devel- 
opment of  the  so-called  salivary  glands  to  be  greatest 
in  species  noted  for  their  efficiency  in  destroying  the 
tissues  of  the  host,  e.g.,  Tylenchus  dipsaci,  Caconema 
radicicola,  and  suggested  that  these  glands  aid  in  dis- 
solving the  host  tissues  and  thus  supplement  the  mechani- 
cal action  of  the  spear  or  onchium,  which  therefore  should 
then  act  also  as  a  spewing  channel.  In  light  of  this,  it 
may  not  be  without  significance  that  the  salivary  glands 
of  Howardula  benigna,  at  the  time  of  entering  its  host, 
appear  better  developed  than  in  some  of  its  nearest  known 
relatives.  Conceivably  this  secretion  is  also  antiseptic. 
Nemas  of  very  many  kinds  make  their  way  through  the  Fig.3.  Egg  of  a  c 
tissues  of  their  hosts  without  causing  fatal  infections.  ^ 

For  instance,  I  have  observed  the  most  important  abdomi- 
nal  and  thoracic   organs,   heart  excepted,  of  Dasyurus 

literally  sewn  through  and  through  by  long  and  slender  nemas  without  apparent 
infection.  The  existence  of  an  antiseptic  nemic  secretion  or  excretion  might  ex- 
plain this.  In  the  case  of  Diabrotica,  there  is  no  known  trace  left  of  the  relative- 
ly large  breach  made  by  the  parasite  (see  Fig.  4),  a  benignant  result  perhaps 
facilitated  by  the  parasite  itself  in  the  way  indicated. 


348 


ANATOMY   OF   ADULT   HOWARDULA 


THE  SOIL-INHABITING  MALE  AND  FEMALE  HOWARDULA,  FIG.  4. 


Female.  ££ X3.§  : '-  "iS " '         '^8  '  '  '  "III    °-57™m  The  colorless 

cuticle  is  traversed  by  plain  transverse  striae,  all  alike,  1.3  microns  apart,  some- 
what difficult  of  resolution  except  with  the  highest  powers.  Very  slightly  oblique 
longitudinal  striae,  due  to  the  attachment  of  the  musculature,  are 
visible  in  most  regions  of  the  body.  Xo  series  of  pores  have  been 
seen  in  the  cuticle.  The  lips  are  amalgamated;  the  lip  region  has 
no  apparent  framework.  Xo  labial  papillae  have  been  seen.  Be- 
hind the  pharynx  the  oesophagus  is  about  one-fourth,  at  the  nerve- 
ring  about  one-fifth,  as  wide  as  the  corresponding  part  of  the  neck. 
The  beginning  of  the  intestine  is  somewhat  indefinite;  but  proba- 
bly is  indicated  by  the  anterior  limits  of  the  minute,  elongate  bire- 
fringents,  grn  bif,  Fig.  4.  A  dorsal  oesophageal  gland  empties 
through  a  duct  and  ampulla  near  the  base  of  the  spear.  Two  large 
coarser  glands  empty  a  trifle  farther  back.  These  glands,  Fig.  4, 

Fig.    4.    Profile    view    of    the   soil-inhabiting   male   and 
female    of    Howardula    benigna.    The    female    has    a    well 
developed  spear;   the  male  none.    The  female  has  three 
strongly    developed    cesophageal    glands;    the    male    none. 
As    in    some    mermithids,    and    in    some    triplonchs,  the 
oesophageal    glands    are    of    two    kinds,    the    dorsal   gland 
differing    in    structure    from    the    two    submedian    ones. 
See  gl  sal  dsl  and  gl  sal  subm.     This  difference  in  struc- 
ture    suggests     a     double     function.    The     abbreviations 
are    self    explanatory. 
The     different     zones 
in    the    vas    deferens 


tsl  mvmm 


generations  of  sperma- 
tidia,  somewhat 
as  in  Spirina.  on 
xst,  vestigial  onchium 
of  the  male. 

J 


X400 


are  reminiscent  of  those  in  the  neck  of  mermithidae  (e.g.  Agamermis  larvae)  and 
of  Tylenchus  and  Heterodera.     The  striking  difference  in  the  composition  of  the 


DEVELOPING    PARASITIC    FEMALE 


349 


glandular  secretions  sug- 
gests two  functions ;  e .g. ,  (1 ) 
solvent  action  on  the  chitin 
of  the  host  at  the  time  the 
nema  drills  into  the  host, 
and  (2)  an  aseptic  effect  to 
aid  in  healing  the  wound 
thus  inflicted  on  the  host. 
Small,  irregularly  poly- 
hedral birefringents  occur 
among  the  spherical  gran- 
ules of  the  intestine.  Very 
small  amphids  are  believed 
to  occur.  There  are  no 
eyespots.  Sometimes  the 
terminus  of  the  female  is 
marked  by  the  presence  of 
one  or  two  small,  back- 
ward-pointing, short,  trun- 
cate, cylindroid  mucronea, 
about  one  micron  long  and 
about  equally  wide.  The 
blind  end  of  the  gonad,  half 
as  wide  as  the  body,  lies 
near  the  middle  of  the 
nema  and  is  directed  for- 
ward. Passing  backward 
two  body  widths,  the  gonad 
becomes  one-third  as  wide 
as  the  body;  five  body 
widths  back  it  is  only 
about  one-fifth  as  wide  as  nrt  rnt 
the  body.  It  then  expands 
a  little,  and  is  separated 
from  the  large  sperm  recep- 
tacle comprising  the  rest  of 
the  gonad,  by  a  rather  dis- 
tinct constriction.  Begin- 
ning narrow  near  the  head, 
the  lateral  chords  widen 
regularly  until  they  reach 
their  full  width, — about 
one-third  that  of  the  body, 
— a  little  behind  the  nerve- 
ring.  Here,  at  intervals 
equalling  the  body  diam- 
eter, the  lateral  chords 
carry  broad  ellipsoid  cells 
about  one-fourth  as  wide 
as  the  body,  containing 


'Iff 


Fig.  5.  Quarter  grown 
Howardula  benigna  removed 
from  the  body  cavity  of  the 
cucumber  beetle,  Diabrotica 
vittata.  The  striations  of 
the  cuticle  are  much  too 
fine  to  be  shown  in  a  figure 
of  this  magnification;  the 
features  shown  at  ruga  are 
folds  in  the  cuticle  depend- 
ent on  the  attitude  of  the 
nema.  The  narrow,  imma- 
ture sexual  organ  is  shown 
dark.  The  spermatheca, 
spthc,  with  its  excessively 
minute  sperm  elements,  is 
shown  overlaid  by  the  much 
coarser  tissues  of  the  body 
wall.  A  few  sperms  occur 
near  the  vulva.  The  uterus 
ultimately  enlarges  so  as 
nearly  to  fill  the  body  cav- 
ity; the  ovary,  ovr,  mean- 
time, is  shoved  forward  into 
the  front  end  of  the  body, 
trm  ovr,  present  position  of 
blind  end  of  ovary. 


X320 


350 


ANATOMY   OF   THE    MALE    HOWARDULA 


spherical  nuclei  two-thirds  as  wide  as  the  cells  themselves;  and  these  nuclei 
carry  spherical  nucleoli  half  as  wide  as  the  nuclei  themselves.  The  inter- 
spaces in  the  chord  are  nearly  filled  by  granules  of  variable  size,  the  largest  one- 
sixth  as  wide  as  the  nema.  The  chords  narrow  in  the  tail  to  near  the  terminus. 
Possibly  there  are  faint  refractive  elements  in  the  inconspicuous  lining  of  the 
oesophagus  indicating  the  presence  of  a  vestigial  bulbous  body.  In  the  specimen 
under  examination  the  cells  near  the  blind  end  of  the  gonad  have  considerable  size, 
being  about  one-fourth  as  wide  as  the  body. 

Male:  *J ^    -Z-  *J£ ^ ?£J    O.G1™  Striae,  1.2  mi- 

crons  apart,  rather  readily  resolvable  with  high  powers.     As  in  the  female,  there  is 

no  perceptible  framework  to  the  lip  re- 
v  gion,  but  six  very  flat  lips  can  be  faintly 
M  seen.  No  papillae  have  been  distin- 
guished on  the  lips.  The  tail  presents  a 
terminal  dimple.  There  is  very  little 
vestige  of  a  spear  in  the  pharynx  (Fig. 
4)  but  the  limits  of  the  pharynx  usually 
can  be  made  out, — its  length  being  a 
little  greater  than  the  width  of  the  base 
of  the  head.  Behind  the  pharynx,  the 
OfT  oesophagus  can  be  seen  to  be  about  one- 
third  as  wide  as  the  base  of  the  head, 
and  it  continues  at  first  more  or  less  nor- 
mal, but  becomes  indefinite.  There  is 
no  distinct  O3sophageal  swelling,  nor  has 
any  vestige  of  such  been  seen.  At  the 
nerve-ring,  the  oesophagus  is  probably 
'IKflKI  less  than  one-third  as  wide  as  the  corre- 
sponding portion  of  the  neck.  The 
cesophagus  is  indefinite  behind,  but 
spherical  granules,  such  as  are  charac- 
teristic of  the  intestinal  cells,  occur 
about  one  body  width  behind  the  nerve- 
ring.  However,  it  seems  likely  that,  as 
in  the  female,  the  first  appearance  of 
birefringents  probably  indicates  the  be- 
ginning of  the  vestigial  intestine.  The 
blind  end  of  the  testis,  about  one-third 
as  wide  as  the  body,  is  indistinct,  and  a 
little  more  than  twice  as  far  from  the 
'  anterior  extremity  as  the  nerve-ring. 
For  about  two  to  three  body  widths  the 


X18 


Fig.  6.  Gonads  of  the  female  cucumber  beetle, 
Diabrotica  tittata,  previous  to  egg-laying,  when  the 
nemic  larvae  swarm  into  the  ovaries. 


testis  increases  in  diameter,  becoming 
half  as  wide  as  the  body,  this  portion 
being  rather  coarsely  and  irregularly 
granular.  The  anal  region  is  very  slightly  raised.  There  are  two,  nearly  straight, 
tapering,  blunt  spicula,  nearly  as  long  as  the  anal  body  diameter.  These  are 


INFESTED   MALE    CUCUMBER   BEETLES 


351 


vaguely  cephalated,  and  at  their  cephalated  ends  are  a  little  wider  than  anywhere 
else.  They  taper  rather  regularly  to  the  blunt  distal  ends.  There  is  a  short,  sim- 
ple, narrow,  refractive  gubernaculum,  about  one-third  as  long  as  the  spicula.  No 
definite  ribs  or  special  papillae  have  been  seen  on  the  tail,  or  in  front  of  the  anus. 
The  wings  project  sufficiently  so  that  the  cross  section  of  the  nema  in  the  vicinity 
of  the  anus  must  be  thrown  out  of  dorso-ventral  symmetry  considerably.  The  pos- 
terior extremity  of  the  male  is  more  or  less  helical,  and,  oppo- 
site the  anus,  the  somewhat  raised  wing  occupies  nearly  one- 
fourth  the  corresponding  width  of  the  body.  The  contour  of 
the  wing  is  almost  imperceptibly  and  very  finely  crenate,  the 
corresponding  annules  of  the  cuticle  here  averaging  about  one 
micron. 

Habitat:  Garden  soils  near  cucurbits,  and  especially  near 
eggs  and  very  young  larvae  of  D.  vittata;  widespread.  The 
spherical  and  refractive  intestinal  granules  hinder  an  examina- 
tion of  other  anatomical  and  histological  features. 

Possible  transfer  of  nemas  by  beetles  in  copula. 

Males  and  females  of  D.  vittata  were  gathered  and  examined 
for  their  nematization  with  H.  benigna.  Of  15  females,  7  were 
infested;  8  not  infested.  Of  29  males,  17  were  infested;  12  not 
infested.  Roughly  speaking,  therefore,  there  was  a  50  per  cent 
nematization,  of  which  each  sex  had  about  half  its  individuals 
nematized.  This  seemed  a  suitable  case  to  scrutinize  with  re- 
gard to  the  transfer  of  larval  Howardulas  from  the  male  beetle 
to  his  mate. 

Of  19  infested  males,  7  had  nemas  in  the  genitalia,— the 
number  of  nemas  varying  from  1  to  14.  The  nemas  seemed  to 
tend  to  gather  in  the  distal  end  of  the  genitalia,  though  found 
in  all  parts. 

Following  up  this  observation,  beetles  in  copula  were  gath- 
ered and  the  females  examined.     If  the  female  was  infested  in  malTcucumb7rl:>eetle* 
the  body  cavity,  she  was  not  further  examined;  if  not  infested  tst,  testis;  gl,  glands, 
in  the  body  cavity,  then  her  more  external  genitalia  were  scru-  Note  nemas  in  cavity 

,..,.,  ,  u-T-Tr          j  uu  j  j.      °f      genitalia,       genit 

tinized  for  larval  nemas,  which,  if  found,  could  be  assumed  to  (white)  and  ros 
have  been  placed  there  by  the  males  with  which  these  females  (black)'.  Nemas  seem 
were  known  to  have  copulated.  less  abundant  in  male 

Examination  of  13  such  non-nematized  females  disclosed  no  ge 
larvae  of  Howardula  in  the  distal  genitalia.  This  might  seem  to  indicate  that 
such  transfer  of  Howardula  larvae  from  male  beetle  to  female  was  improbable. 
On  the  other  hand,  no  sperms  were  found  in  these  females,  although  they  were  pres- 
ent in  all  the  males  examined.  The  fact  that  no  sperms  were  transferred  to  the  fe- 
males seems  to  indicate  that  the  copulation  was  a  mere  gesture,  which  did  not 
result  in  fertilization.  The  females  were  not  yet  at  the  egg-laying  stage,  as  was 
indicated  by  the  condition  of  their  ovaries.  In  only  one  female  examined  dur- 
ing the  whole  of  these  examinations  was  an  egg  found  lower  down  than  the 
ovaries.  This  egg  was  in  an  infested  female  and  had  two  or  three  nemas  on  its 
surface;  the  egg  was  in  the  oviduct.  This  experiment  should  be  repeated. 


nan 

Fig.    7.  Gonads    of 


352 


GUIDE  ECOLOGY  TO  FAVOR  AGRICULTURE 


The  present  investigations  suggest  how  far  we  are  from  appreciating  the 
abundance  and  importance  of  insect  parasites  and  how  backward  in  attempting 
their  control.  Howardula  is,  beyond  any  reasonable  question,  ages  old,  for 
on  no  other  supposition  can  the  remarkable  relationship  of  host  and  parasite 
be  explained.  It  is  only  one  of  a  consider- 
able number  of  parasites  of  the  same  destruc- 
tive insect  that  have  much  to  do  with  the 
welfare  of  the  host.  Intelligently  increasing 
the  incidence  of  the  parasite  will  decrease 
the  ravages  of  the  host.  When  we  come  to 
understand  these  relationships,  these  "bal- 
ances" between  host  and  parasites,  doubtless 
we  can  do  much  toward  inclining  the  "bal- 
ance" in  our  favor.  We  hear  more  or  less  of 
organisms  introduced  to  new  areas  without 
their  enemies  and  parasites,  and  in  conse- 
quence becoming  frightful  pests;  and  we  have, 
very  painfully  and  slowly  it  seems  to  some  of 
us,  learned  that  searching  for  and  introduc- 
ing these  same  enemies  and  parasites  affords 
relief.  Marked  successes  of  this  kind  at  last 
place  it  beyond  doubt  that  this  portion  of 
the  field  of  economic  parasitology  will  be  Jjfe  8gru£e*ddof  *^^ 

Carefully     explored.      But     there     is     another   entering  the  grub.    The  sharp  active  man- 

very  important  part  of  the  field  of  which  we  Jgft?g •n^uald'eemtaberatherimPass- 
hear  little  if  anything,  and  that  is  the  com- 
prehension and  watchful  control   of  what   may  be  termed  indigenous  or  long- 
established  "balances." 

The  cucumber-beetle  affords  good  enough  example  of  these  latter  to  justify 
an  appeal,  on  the  basis  of  it,  to  economic  biologists  to  scrutinize  more  carefully 
the  ever  changing  "balances"  between  pests  and  their  parasites  and  other  ene- 
mies, including  pests  of  long  standing,  with  a  view  to  keeping  the  "balance" 
always  inclined  in  our  favor.  I  believe  any  well  trained,  experienced  and 
thoughtful  biologist  will  agree  that  such  a  course  is  bound  finally  to  result  in 
notable  economies.  A  case  in  point  is  the  existence  of  localities,  among  those 
here  tested,  in  which  the  total  zoo-parasitism  of  the  beetles  reached  only  about 
two  per  cent.  At  the  same  time  not  very  far  away  there  was  a  nemic  infesta- 
tion exceeding  fifty  per  cent  and  a  dipterous  infestation  exceeding  forty  per  cent. 
The  investigation  showed  that  the  transference  by  post  of  the  two  parasites 
mentioned  from  highly  infested  areas  to  low  or  non-infested  areas  was  easily 
feasible  at  small  cost.  Beetles  simply  posted  in  a  ventilated  box  containing 
cucurbit  leaves  survived  a  two  to  four  days'  journey;  turned  loose  at  night 
they  lived. 


MARIONELLA1 

(Eurystoma  Marion,  1870); 

an  emendation,  with  notes  on  a  new  birefringent  substance, 
mariohellin,  found  in  the  intestinal  cells. 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XI 
BY  N.  A.  COBB 

United  States  Department  of  Agriculture 

Marionella,2  nom.   nov. 

Eurystoma  Marion,  Ann.  Sci.  Nat.  Zool.  V.   13:  19.  1870.     Not  Eurystoma 
Raf.  1818. 

Cuticle  and  setae.— The  thin  layers  of  the  transparent,  colorless  cuticle  are 
traversed  by  transverse  striae  so  exceedingly  fine  that  they  are  very  difficult 
to  see  even  with  highest  powers  of  the  microscope.  Occasionally  oblique  striae 
also  are  to  be  seen  in  the  cuticle  of  the  lips,  running  in  the  direction  of  a 
left-handed  screw.  There  are  no  lateral  wings  to  the  cuticle,  and  the  striae 
are  not  altered  on  the  lateral  fields.  There  are  no  longitudinal  striae 
in  the  cuticle  itself,  but  the  attachments  of  the  somatic  muscles  give 
rise  to  longitudinal  markings  of  a  character  somewhat  resembling  true 
striae.  The  contour  of  the  body  is  always  plain. 

The  cephalic  setae,  which  are  one-third  to  two-thirds  as  long  as  the  lip- 
region  is  wide,  are  six  or  ten  in  number.  Even  when  at  first  sight  there  ap- 
pear to  be  only  six,  it  is  frequently  found  that  in  reality  there  are  ten, — 
each  of  the  four  submedian  setae  having  a  very  short  and  very  inconspicuous 
companion  hugging  its  base.  The  setae,  two  lateral  and  four  or  eight  sub-- 
median,  are  usually  slightly  curved,  of  medium  size  to  very  slender,  taper- 
ing, and  somewhat  acute,  and  have  innervations  that  are  most  clearly  visible 
near  their  bases;  they  are  of  medium  stiffness  to  flexible,  and  spread  out- 
ward from  the  lateral  surface  of  the  head  opposite  the  apex  of  the  onchium. 
Occasionally  the  larger  setae  can  be  seen  to  be  about  three- jointed.  There 
are  no  special  subcephalic  setae.  On  the  anterior  portion  of  the  neck  in 
the  vicinity  of  the  head  there  are  always  to  be  found  a  few  small,  slender 
setae,  one-sixth  to  one-eighth  as  long  as  the  corresponding  body  diameter; 
these  usually  project  at  right  angles  to  the  neck  or  incline  forward  at  an  angle 
of  sometimes  as  much  as  forty -five  degrees.  Not  infrequently  among  the 
cervical  setae  there  is  one,  a  dorsal  one,  two  to  three  times  as  far  back  as 

1  This  paper  was  published  in  the  Journal  of  the  Washington  Academy  of  Sciences, 
vol.  11,  no.  21,  pp.  504-509  (issued  January  9,  1922).     It  is  reprinted  with  changed  pagina- 
tion but  without  change  of  page  content. 

2  The  name  Eurystoma,  applied  by  Marion  in  1870  to  a  new  genus  of  free  living 
marine  nemas  discovered  by  him  near  Marseilles,  France,  was  preempted,  having  been 
applied  by  Rafinesque  in  1818  to  a  genus  of  molluscs.     Naturally,  investigations  made 
during  the  last  half  century  enable  one,  at  the  present  time,  to  emend  Marion's  original 
description.     Having  examined  as  many  more  new,  and  as  yet  unpublished,  species  of  the 
genus  as  have  been  already  published,   I  venture  to  make  this  emendation,  based  on  a 
study  of  about  twenty-five  species,  and  to  propose  for  the  genus  the  new  name  Marionella, 
in  commemoration  of  its  original  author. 


354  MARIONELLA 

the  base  of  the  head,  which  is  more  prominent  than  the  others.  The  somatic 
setae  appear  always  to  be  reduced  to  innervations.  There  are  no  conspic- 
uous pores  on  the  surface  of  the  body,  but  the  ellipsoidal  glandular  cells  of 
considerable  size  invariably  found  in  the  lateral  fields  are  connected  with 
the  exterior  by  means  of  very  small  and  inconspicuous  pores. 

Head  and  pharynx. — The  somewhat  rounded  to  subtruncate  head  is  us- 
ually continuous  with  the  neck,  but  is  sometimes  set  off  by  a  slight  contrac- 
tion, or  by  a  very  slight,  broad,  shallow  constriction.  The  lip-region,  on 
the  other  hand,  is  nearly  always  set  off  by  a  very  slight,  narrow  and  shallow, 
but  usually  distinctly  visible  constriction.  The  membranous  lips  are  them- 
selves thin  and  confluent,  and  apparently  close  by  virtue  of  their  elasticity. 
Their  margins  are  very  finely  striated  and  possibly  sometimes  fimbriate. 
The  lips  are  supplied  externally  with  six  forward-pointing  papillae  (or  six 
sets  of  papillae),  arranged  in  a  single  circlet  having  a  diameter  about  one- 
half  as  great  as  that  of  the  lip-region.  These  papillae  are  so  exceedingly 
small  as  usually  to  escape  observation.  Their  innervations  are  also  exceed- 
ingly inconspicuous.  Usually  it  is  only  when  the  papillae  happen  to  project 
forward  a  little  in  exact  profile  that  they  come  into  view. 

At  first  sight  the  pharynx  appears  to  have  the  form  of  that  of  Oncholaimus. 
It  is,  however,  nearly  always  divided  into  two  distinct  chambers  of  more  or 
less  equal  length,  the  anterior  of  which  is  somewhat  the  wider  and  the  more 
symmetrical.  This  regular  anterior  chamber  is  nearly  always  a  napiform 
cavity  one-half  to  two-thirds  or  even  three-fourths  as  wide  as  the  correspond- 
ing portion  of  the  head.  The  posterior  chamber  is  of  smaller  size,  usually 
only  about  three-fourths  as  wide  as  the  anterior  chamber,  and  more  or  less 
irregularlv  spheroidal  in  form.  The  refractive  walls  of  the  pharynx  are 
well-developed,  but  not  very  thick.  The  pharynx  is  usually  armed  with  a 
single  well-developed,  forward-pointing  onchinm,  but  there  may  be  one  or  two 
additional  smaller  onchia  in  exceptional  cases.  The  apex  of  the  main,  and 
usually  only,  onchium,  always  occupying  the  right  ventral  submedian  posi- 
tion, extends  forward  sometimes  as  far  as  the  lips.  The  convex-conoid, 
enlarged  base  of  the  onchium  fills  the  posterior  chamber  of  the  pharynx 
comparatively  full.  This  enlarged  portion  of  the  onchium  is  continued  in 
the  front  chamber  by  a  narrower,  more  slowly  tapering,  convex-conoid, 
more  or  less  acute  summit.  This  organ  is  perforated  and  so  serves  as  the 
outlet  of  a  large  oesophageal  gland.  The  posterior  pharyngeal  chamber  is 
separated  from  the  anterior  by  a  constriction,  marked  in  its  most  pronounced 
form  by  the  presence  of  narrow  and  refractive,  transverse,  arcuate  elements 
or  thickenings,  placed  end  to  end  in  a  circle.  Adjacent  to  this  circle,  usually 
in  front  of  it  and  close  together,  there  are  one  to  three  transverse  rows  of 
denticles,  each  consisting  of  either  about  thirty-two,  or  about  sixty-four 
to  eighty,  somewhat  forward-pointing  units.  These  more  or  less  inward 
pointing  denticles  are  rather  acute,  cylindroid-conoid,  uniform  in  size,  and 
are  usually  so  minute  as  to  be  barely  resolvable  with  high  powers  of  the 
microscope. 

When  viewed  from  in  front,  the  pharynx  is  seen  to  be  very  nearly  round. 
The  margin  of  the  lip-region  is  so  thin  and  filmy  that  oftentimes  it  is  difficult 
to  delimit.  An  exact  count  of  the  denticles  in  a  specimen  of  an  unpublished 
but  typical  species,  gave  the  following  figures: — anterior  series  of  denticles 
62 ;  second  series  62 ;  back  series  of  larger  denticles  20 ; — this  decreased  number 
in  the  back  row  being  due  not  only  to  the  fact  that  the  denticles  are  larger 


MARIONELLA  355 

and  farther  apart,  but  also  to  the  fact  that  one-third  of  the  circumference 
is  destitute  of  denticles,  namely  that  part  of  the  circumference  opposite 
the  large  onchium.  In  this  particular  region,  however,  the'interior  walls 
of  the  pharynx  are  very  finely  longitudinally  striated.  The  back  row  of 
denticles,  it  should  be  pointed  out,  is  on  the  wall  of  thfe  posterior  half  of  the 
pharynx. 

The  neck  is  conoid,  or  occasionally  subcylindroid,  and  ends  in  a  cylindroid 
or,  more  often,  a  rather  decidedly  convex-conoid  head. 

Amphids  and  eye-spots. — Though  the  amphids  are  well-developed,  they 
are  rarely  plainly  to  be  seen.  Their  exterior  expression  consists  of  two  dor- 
sally  sub-lateral  concavities  two  to  three  times  as  wide  as  long,  impinging  on 
the  bases  of  the  lateral  setae.  Though  the  peripheries  of  the  amphids  may 
seem  to  be  closed,  they  are,  in  fact,  nearly  always  found  to  be  open  on  the 
posterior  margin  near  the  lateral  fields.  As  a  rule  their  contours  are  almost 
invisible,  so  that  their  form  and  extent  are  mainly  indicated  by  the  apparent 
absence  in  them  of  the  fine  structural  elements  to  be  seen  elsewhere  in  the 
cuticle  of  the  head.  When  clearly  defined,  their  contours  are  found  to  be 
reniform  with  the  convex  side  forward.  They  are  located  on  or  near  the 
base  of  the  lip-region,  and  more  or  less  opposite  to  the  rows  of  denticles. 
They  are  usually  one-third  to  two -fifths  as  wide  as  the  corresponding  diameter 
of  the  lip-region  and  two  to  three  times  as  wide  as  long. 

More  often  than  not  two  eye-spots  are  present.  These  take  the  form  of  sphe- 
roidal, compact  collections  of  about  one  hundred  brownish  granules,  each 
collection  lateral  in  position  and  lying  between  the  oesophagus  and  body- 
wall, — being  about  one-fourth  as  wide  as  the  corresponding  portion  of  the 
neck,  and  removed  from  the  anterior  extremity  by  a  distance  two  to  four 
times  as  great  as  the  width  of  the  head.  Anteriorly,  these  ocelli  often  present 
a  spherical  cavity  in  which  there  is  at  least  the  suggestion  of  a  spherical 
lens. 

Oesophagus. — The  simple  conoid  oesophagus  is  destitute  of  bulbs  and 
receives  the  base  of  the  pharynx  in  its  anterior  extremity,  where  it  is  usually 
about  half  as  wide  as  the  base  of  the  head.  Near  the  nerve-ring  it  is  usually 
about  one-half,  and  posteriorly  usually  about  three-fifths,  as  wide  as  the 
corresponding  part  of  the  neck.  It  is  always  separated  from  the  intestine 
by  a  distinct  cardiac  collum  about  one-third  as  wide  as  the  base  of  the  neck. 
While  not  conspicuous,  the  lining  of  the  oesophagus  is  a  distinct  feature 
throughout  its  length.  Though  the  oesophageal  musculature  is  usually 
fine,  the  structure  is  occasionally  coarse  in  the  posterior  part.  Rarely, 
yellowish  spherical  granules  are  found  in  the  tissues  of  the  oesophagus. 
The  oesophageal  glands  are  well-developed,  or  at  least  one  of  them  is;  as 
before  stated,  they  empty  into  the  pharynx  through  pores  in  the  onchia. 
The  right  submedian  gland  is  without  exception  the  largest.  There  is  us- 
ually a  well-developed  conoid  or  hemispherical  cardia  one-third  to  one-half 
as  wide  as  the  corresponding  portion  of  the  neck. 

Intestine. — The  intestine  becomes  at  once  one-half  to  two-thirds  as  wide 
as  the  body,  and  is  made  up  of  cells  of  such  a  size  that  few  are  required  to 
build  a  circumference.  Its  walls  are  thick,  and  its  lumen  faint.  Its  cells 
invariably  contain  fine  spherical  granules  of  more  or  less  variable  size,  the 
largest  of  them  being  one-fortieth  to  one-twentieth  as  wide  as  the  body. 
The  granules  are  scattered,  or  sometimes  numerous,  in  the  cells,  and  may 
be  so  arranged  as  to  give  rise  to  a  faint  tessellated  effect,  though  this  is  unusual. 


356  MARIONELLA 

Doubly  refractive  granules  (Marionellin}  in  the  intestinal  cells. — In  the 
single  layer  of  cells  composing  the  intestine,  an  undescribed  species  of  Mari- 
onella  presented  about  twenty  scattered  special  cells,  more  numerous  and 
closer  together  anteriorly,  each  packed  with  doubly  refractive  granules 
(marionellin)  mostly  of  very  small  size.  Marionellin  occurs  in  other  species 
of  Marionella. 

These  special  intestinal  cells  were  not  distributed  along  a  definite  longi- 
tudinal line  as  in  Ironus,  where  there  is  a  decided  dorsb-ventral  symmetry 
to  the  intestine  due  to  the  dorsal  cells  having  a  different  character  from 
the  ventral.  The  interspaces  between  these  special  cells  in  this  species  of 
Marionella  increased  rather  regularly  from  front  to  rear. 

The  discovery  of  these  special  intestinal  cells  is  an  additional  observation 
indicating  differentiation  among  the  cells  of  the  nema  intestine.  Such  differ- 
entiated cells  are  now  known  to  the  writer  in  the  following  genera,  among 
others:  Enoplus,  Bathylaimus,  Ironus,  Mononchus,  Eurystoma  (all  carniv- 
orous). It  seems  very  reasonable  to  suppose  that  these  differentiated  cells 
may  have  functions  similar  to  those  of  the  glands  accessory  to  the  intestine 
of  other  and  larger  animals.  Assuming  that  digestion  in  nemas  has  a  general 
similarity  to  that  of  the  higher  animals,  it  would  seem  that  gastric,  hepatic, 
renal  and  other  functions  must  exist  in  some  form  in  the  nema;  thus  far, 
however,  very  few  of  these  functions  can  be  assigned  to  special  organs,  as 
few  or  no  such  special  organs  exist.  Instead  of  each  cell  of  the  intestine 
carrying  out  all  of  these  distinct  functions,  in  view  of  the  above  observations 
there  is  now  morphological  evidence  of  "division  of  labor,"  and  when  these 
differentiated  cells  have  been  adequately  investigated,  we  shall  probably  be  able 
to  assign  to  them  definite  functions,  and,  for  illustration,  be  able  to  apply  to 
them  some  such  terms  as  "hepatic  cells,"  "renal  cells,"  "splenic  cells,"  etc. 

Tail. — The  tail  in  Marionella  takes  on  one  of  two  distinct  forms,  accord- 
ing as  there  is  or  is  not  a  spinneret  present.  If  there  is  no  spinneret  the  tail 
is  conoid  from  the  anus  to  the  acute  terminus,  sometimes  however  tapering 
a  little  more  rapidly  in  the  anterior  portion  than  elsewhere.  In  species 
possessing  this  form  of  tail,  usually  the  tail  of  the  male  is  the  shorter,  and 
the  narrow  conoid  posterior  part  may  appear  rather  as  an  appendage  to  the 
short  but  bulky  anterior  part.  Most  of  the  species,  however,  possess  three 
well-developed  unicellular  caudal  glands  and  a  blunt,  conoid,  unarmed,  and 
symmetrical  terminal  spinneret  about  one-fourth  as  wide  as  the  base  of  the 
tail.  If  any  setae  occur  on  the  tail,  they  are  exceedingly  small  and  very 
inconspicuous.  The  three  quite  separate  ducts  of  the  caudal  glands  are 
plainly  visible  in  the  tail  and  end  posteriorly  in  three  separate  ampullae. 
The  unicellular  glands  themselves  are  arranged  in  a  loose  tandem  in  front 
of  the  anus,  the  foremost  being  removed  a  distance  from  the  anus  several 
times  as  great  as  the  corresponding  body  diameter. 

Lateral  fields:  glandular  cells. — The  lateral  fields  are  usually  about  half 
as  wide  as  the  body,  and  contain  large,  granular,  ellipsoidal,  glandular  cells 
about  one-third  as  wide  as  the  body  and  emptying  on  the  surface  of  the 
cuticle  by  means  of  exceedingly  minute  pores.  These  large  glandular  cells 
are  situated  from  point  to  point  throughout  the  length  of  the  body,  the 
•distance  between  them  being  from  one  to  four  times  as  great  as  the  width 
of  the  body 

Renette. — The  renette  cell  is  invariably  situated  behind  the  neck  and 
empties  by  means  of  a  long,  narrow,  faintly  visible  duct.  The  narrow  in- 


MARIONEIyl/A  357 

-conspicuous  ampulla  is  situated  nearly  opposite  the  base  of  the  pharynx. 
The  obscure  excretory  pore  is  invariably  located  in  the  lip-region  opposite  the 
row  of  cephalic  setae.  The  presence  of  the  duct  and  ampulla  usually  causes 
the  pharynx  as  well  as  the  portion  of  the  oesophagus  near  the  head  to  be  a 
little  nearer  to  the  dorsal  side  of  the  body  than  to  the  ventral. 

Nerve-ring. — The  nerve-ring  is  always  a  rather  conspicuous  feature.  As 
a  distinct  collar  it  surrounds  the  oesophagus  a  trifle  obliquely  and  is  of  me- 
dium size,  and  has  arranged  both  in  front  of  it  and  behind  it  numerous  large 
nuclei,  whose  grouping,  however,  does  not  appear  to  be  very  orderly. 

Female  organs. — The  female  sexual  organs  are  invariably  double  and  re- 
flexed  (T).  The  vulva,  though  large,  is  more  or  less  continuous  and  not 
very  conspicuous.  The  well-developed  vagina  leads  inward  at  right  angles 
to  the  ventral  surface  about  two-fifths  of  the  way  across  the  body,  and, 
though  fairly  muscular,  is  not  very  amply  cutinized. 

The  two  straight  uteri  are  of  such  a  size  as  to  contain  two  or  more  eggs 
at  a  time,  arranged  tandem;  these  latter  are  thin-shelled,  smooth,  usually 
ellipsoidal  or  somewhat  elongated,  and  are  deposited  before  segmentation 
begins.  The  reflexed  ovaries  are  broad,  or  of  medium  width,  taper  more 
or  less,  and  extend  one-half  to  two-thirds  the  distance  back  to  the  vulva. 
The  ova  in  them  are  arranged  single  file  except  near  the  blind  end,  where 
they  are  arranged  irregularly. 

Male  organs. — -The  tail  of  the  male  is  like  that  of  the  female  except  that 
it  is  usually  shorter  and  more  pronounced  in  its  features,  especially  in  species 
lacking  a  spinneret.  Tn  all  the  species  that  have  been  carefully  examined 
in  this  respect,  namely  in  the  majority  of  the  species,  there  are  two  outstretched 
testes  extending  in  opposite  directions,  the  anterior  one  ending  a  neck -length 
or  more  behind  the  cardia,  the  other  near  the  beginning  of  the  posterior 
fourth  of  the  body.  The  two  equal  spicula  are  invariably  arcuate,  and 
occasionally  strongly  so.  At  their  widest  part  they  are  one-sixth  to  one- 
eighth  as  wide  as  the  corresponding  portion  of  the  body.  They  are  from 
one  and  one-fourth  to  two  times  as  long  as  the  anal  body  diameter,  and 
when  viewed  in  profile  their  proximal  ends  appear  to  lie  opposite  to  or  slightly 
dorsad  from  the  body  axis, — very  rarely  ventrad.  The  proximal  ends  are 
almost  always  very  slightly  cephalated  by  expansion,  but  they  are  some- 
times faintly  cephalated  by  constriction  or  by  contraction.  They  are  some- 
what slender,  of  rather  uniform  width,  and  rather  blunt  at  the  free  end, 
where  they  sometimes  terminate  in  a  simple  or  denticulate  crochet.  The 
gubernaculum,  placed  at  right  angles  to  the  distal  parts  in  the  spicula,  though 
sometimes  of  uniform  width,  usually  tapers  internally  to  a  blunt  or  acute 
point,  which  lies  opposite  to  or  dorsad  from  the  body  diameter.  From 
this  apophysis  muscles  lead  fore  and  aft  to  the  dorsal  body  wall.  The  por- 
tion of  the  gubernaculum  applied  to  the  spicula  is  one-sixth  to  one-eighth 
as  long  as  these  latter. 

Supplementary  organs. — Invariably  two  large,  ventral,  pre-anal  supple- 
mentary organs  are  present,  though  in  a  few  species  they  are  more  or  less 
vestigial.  They  are  placed  in  front  of  the  anus  in  such  fashion  that  the 
posterior  one  is  about  as  far  in  front  of  the  anus  as  the  spinneret  is  behind 
it,  and  the  anterior  one  about  as  far  in  front  of  the  posterior  as  this  latter 
is  in  front  of  the  anus.  There  is,  however,  some  variation  in  the  situation 
of  this  pair  of  supplementary  organs  in  the  different  species.  Nearly  al- 
ways the  posterior  supplement  is  a  little  smaller  than  the  anterior,  some- 


358  MARIONEIXA 

times  markedly  so.  When  well-developed,  these  organs  consist  of  highly 
refractive  elements,  both  external  and  internal,  which  are  very  striking  in 
their  appearance.  To  a  considerable  extent  these  supplements  can  be  pro- 
truded and  withdrawn.  When  protruded  they  are  very  prominent.  When 
withdrawn  they  may  leave  the  ventral  contour  comparatively  even;  and 
yet,  even  when  withdrawn,  they  are  hardly  less  conspicuous  than  when 
protruded,  owing  to  their  highly  refractive  character.  The  most  striking 
internal  elements  are  two  in  number  to  each  supplement,  extending,  one 
forward  and  the  other  backward,  and  may  appropriately  be  termed  "levers'* 
These  levers  are  somewhat  finger-shaped  pieces  of  cutinized  material  that 
serve  for  the  attachment  of  muscles.  They  usually  taper  but  little,  and 
their  internal  extremities  are  invariably  blunt.  The  two  levers  of  a  given 
supplement  are  usually  practically  equal  in  size.  When  the  supplement 
is  at  rest,  the  levers  lie  near  the  ventral  side  of  the  body  and  parallel  to  it. 
In  such  circumstances  the  exterior  portion  of  the  organ  protrudes  only  slightly; 
but  when  the  free  inner  ends  of  the  levers  are  drawn  inward  so  that  they  lie 
at  an  angle  with  the  ventral  surface,  sometimes  as  great  an  angle  as  forty- 
five  degrees,  the  external  portions  of  the  supplements  are  protruded.  The 
external  portion  of  each  organ  has  the  form  of  a  laterally  compressed  cup, 
or  trough,  whose  profile  is  exteriorly  flat,  or  more  often  slightly  concave, 
and  interiorly  more  or  less  semi-circular.  While  the  depth  of  the  organ  may 
sometimes  equal  its  width,  often  it  is  less,  and  sometimes  only  one-half  or 
one-third  as  great.  Those  species  showing  the  maximum  development  of 
the  supplementary  organs  present  cases  where  the  depth  of  the  organ  is 
one-fourth  as  great  as  the  corresponding  diameter  of  the  body.  In  one  species 
the  supplementary  organs  are  asymmetrical,  the  anterior  lever  or  anchor 
having  become  vestigial,  and  the  anterior  portion  of  the  cup  or  trough  having 
diminished  relatively  in  size,  so  that  the  contour  of  the  longitudinal  section 
of  the  organ  is  triangular  rather  than  semicircular.  By  means  of  a  duct 
each  supplementary  organ  is  connected  internally  and  forward  with  a  large 
glandular  cell,  as  in  Bolbella. 

Setae  on  the  male. — Just  in  front  of  the  anus  on  the  male  there  are  usually 
to  be  found  a  few  minute  setae,  either  ventral  or  subventral  in  position. 
They  are  very  short  and  very  inconspicuous.  There  may  be  a  single  one 
at  the  anus;  more  often  there  are  one  or  two  subventral  ones  on  each  side 
Occasionally  there  are  two  rows  extending  to  near  the  posterior  supplement. 
These  setae  are  arcuate,  acute,  and  when  two  are  present  on  each  side  of 
the  anus,  one  of  the  pair  is  usually  located  immediately  behind  the  other 
and  is  of  smaller  size.  No  other  papillae  or  setae  have  been  observed  on 
the  tail  end  of  the  male.  There  is  no  bursa. 

Habitat. — The  genus  Marionella  has  hitherto  been  supposed  to  be  of  rather 
small  size.  It  is  in  reality  large,  and  is  widespread  in  the  various  oceans. 
While  the  individuals  of  a  given  species  may  not  be  numerous,  or  very  wide- 
spread, the  number  of  specific  forms  observed  is  yearly  augmenting.  The 
two  sexes  are  about  equally  common. 

The  genus  is  most  nearly  related  structurally  to  Bolbella,  Symplocostoma, 
Thoonchus  and  Catalaimus. 

Marionella  spectabilis  (Marion)  is  still  retained  as  the  type  species. 


GREEFFIELLA' 

(Trichoderma  Greeff,  1869;    not  Trichoderma  Steph.  1835) 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGV,  XII 
BY  N.  A.   COBB 

United  States  Department  of  Agriculture 

In  1869,  Greeff  described  an  externally  peculiar  and  very  interesting 
small  animal  form  under  the  name  Trichoderma.  Though  it  proves 
in  the  end  to  be  internally  a  typical  nema,  it  is  only  after  many  years 
that  the  fact  becomes  fully  established.  The  minute  size  of  the  species 
and  the  fact  that  the  setose  cuticle  obscures  the  internal  organs,  taken 
together,  have  delayed  a  fuller  understanding  of  the  internal  anatomy. 

Opportunity  has  occurred  to  reexamine  a  species  of  this  genus  in  a 
living  condition,  and  the  results  are  presented  herewith.  They  serve 
to  establish  the  view  that  the  genus  comprises  typical  nemas  pre- 
senting striking  relationships  to  Desmoscolex.  Greeff 's  original 
discovery  is  commemorated  by  renaming  the  genus  Greeffiella. 
G.  oxycaudata  (Greeff)  is  retained  as  the  type  species. 
Greeffiella,  nom.  nov. 

Trichoderma  Greeff,  Arch.  f.  Naturg.,  Berlin,  v.  35,  bd.  1,  1869.  Not 
Trichoderma  Steph.,  1835,  or  Swains.,  1839. 

1-5       10.4 13. 56. 70.  . 

Greeffiella  dasyura  n.  sp.  3. 4  $.(>,  13.  15.  "  9.s  "  The  thin  layers 
of  the  transparent,  colorless,  hairy  cuticle  are  traversed  by  about  fifty-six 
plain  transverse  annules,  easy  of  resolution,  which  are  not  materially  altered 
on  the  lateral  fields.  The  number  of  annules  corresponds  with  the  number 
of  encircling  rows  of  somatic  setae.  While  there  are  no  wings  opposite  the 
lateral  fields,  wing  spaces  are  faintly  indicated  by  a  slight  spareness,  or  absence, 
of  setae  near  the  lateral  lines ;  this  however  is  a  faint  feature  extending  only 
from  the  neck  to  the  anus,  and  is  perhaps  more  pronounced  on  the  female  than 
on  the  male.  The  contour  of  the  body  is  crenate,  especially  toward  the 
head.  There  appear  to  be  toward  thirty  small  unequal  cephalic  setae  on  the 
front  of  the  head,  disposed,  apparently,  in  two  closely  approximated  cir- 
clets. These  setae  average  to  be  about  as  long  as  the  head  is  wide  and  are 
apparently  too  numerous  and  crowded  to  permit  of  any  exact  order ;  however, 
about  twelve  of  the  anterior  ones  are  spread  outward  and  forward  while 
all  the  others  spread  out  more  or  less  backward.  These  somewhat  curved, 
rather  slender,  tapering  acute,  somewhat  stiff  cephalic  setae  are  of  the  same 

1  This  paper  was  published  in  the  Journal  of  the  Washington  Academy  of  Sciences, 
vol.  12,  no.  13,  pp.  229-303  (issued  July  19,  1922).  It  is  printed  with  changed  pagina- 
tion but  without  other  material  alteration. 


360 


GREEFFIELLA 


set  mi 


X1000 


character  as  the  great  bulk  of  the  somatic  setae.  Among  the  somatic  setae  how- 
ever are  a  few  relatively  large,  hollow,  open  bristles  of  another  character,  resem- 
bling the  locomotor  bristles  found  on  Draconema,  Desmoscolex,  etc.  For  in- 
stance, on  the  third  and  eighth 
annule  of  the  female,  and  on  the 
second  and  seventh  annule  of  the 
male,  that  is  to  say  in  the  rows  of 
setae  on  these  annules,  there  occur 
subdorsal  (on  the  second  and  third 
annules)  and  dorsally  submedian 
(on  the  seventh  and  eighth  annules) 
pairs  of  spreading  tubular  open- 
mouthed  setae,  or  bristles,  a  little 
longer  than  the  regular  somatic 
setae.  These  special  setae  have 
extra  large  bases  and  are  probably 
connected  with  glands.  The  rows 
of  ordinary  cervical  setae  have  a 
fringe  of  shorter  setae  in  their 
midst.  As  before  remarked,  the 
somatic  setae  are  in  fifty-six  or 
fifty-seven  transverse  rows, — ex- 
cluding those  on  the  head,  but 
counting  the  finely  pilose  region 
in  front  of  the  spinneret  as  two 
annules.  See  Fig.  3.  Passing  back- 
ward, the  setae  grow  steadily  longer 
from  the  head  to  the  tail ;  the  poste- 
rior ones  are  about  one  and  one-half 
times  as  long  as  the  spinneret, 
while  the  anterior  ones  are  some- 
what shorter  than  the  spinneret. 
Back  as  far  as  the  beginning  of  the 
intestine,  the  rows  of  setae  present 
minute  toothed  fringes,  accentu- 
ating the  annules.  The  conoid  neck 
ends  in  a  rounded,  somewhat 
flattish  hemispheroidal  head,  set  off  by  a  narrow,  deep  and  distinct  constric- 
tion. The  lips  are  amalgamated  and  fixed.  Nothing  is  known  concerning 
the  labial  papillae.  The  pharynx  is  exceedingly  minute  and  easily  overlooked, 
but  is,  in  fact,  a  minute,  simple,  obscure,  straight,  regular,  tubular,  closed, 
unarmed  region  about  one-sixth  as  wide  as  the  head  and  twice  as  long  as  wide ; 
these  measurements  include  its  enclosing  pharyngeal  tissue.  Under  ordinary 
circumstances  there  is  to  be  seen  here  only  a  closed  lumen.  Passing  back- 
ward from  the  pharynx,  the  oesophagus  for  a  distance  two  and  one-half  times 
as  great  as  the  width  of  the  head,  is  cylindroid;  however,  it  widens  slightly, 
so  that  it  becomes  as  wide  as  the  head,  or  one-half  as  wide  as  the  corresponding 
portion  of  the  neck,  that  is  to  say  that  portion  of  the  neck  marked  by  the  fifth 
circlet  of  cervical  setae.  At  this  point  there  is  a  rather  faint  diminution  of 
the  oesophagus,  which  continues  thence  a  little  narrower,  afterward  widening 
out,  and  then  soon  coming  to  contain  granules  like  those  found  in  the  cells  of 
the  intestine.  This  latter  appears  to  begin  about  opposite  the  tenth  row  of 
setae.  There  are  two  narrow  ducts,  one  emptying  into  the  posterior  part  of 


Fig.  1.— Head  end  of  Greeffiella  dasyura.  The 
setae  on  several  annules  immediately  behind  the 
head  have  been  omitted  so  as  to  show  internal 
details  more  clearly,  amph,  amphid ;  an,  annule ; 
int,  location  of  the  beginning  of  the  intestine 
(see  also  Fig.  2.) ;  lum  oe,  lumen  of  the  oesopha- 
gus; oe,  oesophagus;  or,  mouth  opening;  ph, 
pharynx;  set  cph,  cephalic  setae, — a  number  of 
which  are  omitted ;  set  som  maj,  one  of  the  larger 
somatic  setae;  set  som  min,  one  of  the  smaller 
somatic  setae;  set  tb,  tubular  setae. 


361 


srt  cp/i 


each  amphid;  these  ducts  can  be  followed  backward  to  near  the  pigmented 
bodies  soon  to  be  mentioned,  and  possibly  may  be  connected  with  them.  The 
external  expressions  of  the  amphids,  each  of  which  is  symmetrical  to  two 
lines,  are  of  unequal  diameter,  without  central  markings,  and  are  located 
toward  the  front  of  the  head;  they  are  about  as  wide  as  the  corresponding 
portion  of  the  head,  each  being  about  twice  as  wide  as  long.  The  two 
greenish  pigmented  bodies  mentioned  above  (org?,  Fig.  2),  are  olive  green  in 
color  and  present  a  nucleus  in  the  midst 
of  a  colorless  spherical  cell  ( ?)  as  wide 
as  one  of  the  cuticular  annules  in  the 
immediate  vicinity.  These  bodies  are 
naturally  rather  difficult  to  observe 
on  account  of  the  hairy  nature  of  the 
cuticle  through  which  they  are  viewed ; 
they  are  located  well  outside  the  in- 
testine, one  on  each  side  of  the  body, 
somewhat  behind  the  base  of  the  neck. 
The  broad  cardiac  constriction  lies 
opposite  the  eighth  to  tenth  rows  of 
setae,  and  is  about  as  wide  as  the 
distance  between  these  rows.  The 
thick-walled  intestine  presents  a  faint 
lumen  and  is  composed  of  cells  of 
such  a  size  that  about  twelve  occur 
in  each  cross  section.  In  the  male,  at 
least,  the  intestine  gradually  becomes 
one-half  as  wide  as  the  body.  There 
is  no  pre-rectum.  From  the  minute 
anus,  whose  anterior  lip  is  somewhat 
elevated,  the  inconspicuous  rectum 
extends  inward  at  right  angles  to  the 
ventral  surface  half  way  across  the 
body;  the  intestine  itself  extends  past 
the  anus.  No  anal  muscles  are  to  be 
seen.  There  are  two  kinds  of  colorless 
granules  of  variable  size  to  be  seen  in 
the  cells  of  the  intestine;  the  largest 
of  these  have  a  diameter  equal  to  the 
distance  between  the  rows  of  somatic 
setae;  the  finest  of  the  granules  are 
exceedingly  fine.  The  granules  are  not 
so  arranged  as  to  give  rise  to  a  tessel- 
lated effect.  The  more  or  less  convex-conoid  tail  tapers  from  in  front  of  the 
anus  to  the  tubular  spinneret,  which  comprises  two-sevenths  of  the  whole 
tail.  This  tubular  spinneret  is  about  as  wide  as  one  of  the  spicules  of  the 
male;  it  is  a  simple  truncate  affair  which  tapers  but  very  little.  A  marked 
peculiarity  of  the  posterior  extremity  of  the  nema  is  the  existence  of  numerous 
minute  setae ;  for  a  distance  equal  to  the  length  of  the  spinneret  the  setae  on 
the  portion  of  the  tail  immediately  in  front  of  the  spinneret  are  very  much 
reduced  and  more  numerous.  The  spherical  caudal  glands  are  located  behind 
the  anus  in  the  anterior  fourth  of  the  tail  and  empty  through  separate  ducts; 
each  is  about  one-fifth  as  wide  as  the  corresponding  portion  of  the  tail,  or  as 
wide  as  one  of  the  somatic  annules  opposite.  Only  two  nuclei  were  seen  in 


dint 


X100° 


grnmajint 

Fig.  2.  —  Internal  anatomy  of  the  head 
end  of  Greeffiella  dasyura.  Lettering  as  in 
Fig.  1.  d  int,  one  of  the  cells  of  the 
intestine;  crd  col,  cardiac  collum;  del  amph, 
duct  connecting  with  the  amphidial  pore; 
grn  maj  int,  one  of  the  larger  intestinal 
granules;  grn  min  int,  smaller  intestinal 
granules;  int,  intestine;  lum  int,  lumen 
of  the  intestine;  nr,  nerve  ring;  org  ?, 
organ  of  doubtful  significance;  set  tb, 
tubular  seta. 


362 


GREEFFIELLA 


connection  with  these  glands,  and  these  were  located  in  the  vicinity  of  the  anus, 
their  number  indicating  that  the  number  of  caudal  glands  may  be  less  than 
the  usual  three.  The  excretory  pore  lies  near  the  nerve-ring  opposite  the  sixth 
annule  in  the  male  and  opposite  the  seventh  in  the  female ;  its  spherical  ampulla 
is  one-fourth  as  wide  as  the  corresponding  portion  of  the  neck.  The  nerve- 
ring  surrounds  the  oesophagus  somewhat  obliquely  where  it  first  diminishes 
in  diameter  somewhat  behind  the  middle.  In  the  dorsal  side  of  the  neck, 
opposite  the  9-14  rows  of  setae  there  are  some  relatively  large  organs, — 
probably  two  or  more  finely  granular  cells.  From  the  somewhat  inconspicu- 
ous, small,  elevated  vulva,  which  is  surrounded  by  minute  setae,  the  small, 
weak,  non-cutinized,  tubular  vagina  leads  inward  at  right  angles  to  the 
ventral  surface  about  one-third  the  distance  across  the  body.  Little  is  known 
concerning  the  double  symmetrically  reflexed  female  sexual  organs. 

1.5         6.6        10.6  'M 


set  m. 


set  min 


.  set  m 


X1000 


>0.34. 


set  tit 


3.2         7.7/       11.  18.        -Ml. 

The  slightly  arcuate,  irregularly 
conoid,  faintly  sigmoid  tail  of  the 
male,    on   the   whole,    rather   re- 
sembles that  of  his  mate.     The 
two  equal,  straight,  very  slender, 
uniform,   acute,   colorless  spicula, 
which  are  slightly  cephalated  by 
expansion,  are  about  one  and  one- 
fourth  times  as  long  as  the  anal 
body  diameter.     If  swung  around 
behind  the  anus,  they  would  just 
about  reach  to  the  base  of  the 
Fig.  3.— Tail  end  of  Greeffiella  dasyma.     Let-   spinneret;  they  are  about  twice  as 
tering  as  in  Figs.  1  and  2.     ann  pnlt,  penultimate   wide  as  the  bases  of  the  somatic 
annule;  ann  ult,  ultimate  annule;  spn,  spinneret,    setae,    are   a   little   larger   distally 

than  elsewhere,  and  are  perhaps 

winged.  No  gubernaculum  has  been  seen.  On  the  fifth  and  eleventh 
annules  in  front  of  the  anus  occur  ventrally  submedian  papilla-like  organs, 
indicated  by  the  presence  of  minute  setae  arranged  in  a  cluster  about  a 
nerve  ending  (?), — about  ten  setae  on  the  fifth  annule  and  a  much  smaller 
number  on  the  eleventh.  There  are  also  similar  ventrally  sublateral  bunches 
of  setae  on  the  annules  preceding  the  large  (duplex?)  conical  one  bearing  the 
spinneret.  On  the  lateral  field  near  the  middle  of  the  male,  a  bunch  of  minute 
setae  was  observed  like  those  on  the  fifth  annule  in  front  of  the  anus.  The 
nature  of  these  special  organs,  for  such  they  must  be,  remains  in  doubt. 
It  seems  quite  possible  that  some  of  them  are  male  supplementary  organs. 
The  wide  cylindrical  testis  is  one-half  as  wide  as  the  body  and  is  reflexed  to 
near  the  proximal  ends  of  the  spicula. 

Habitat:  Found  in  sponges,  Biscayne  Bay,  Florida,  U.  S.  A.,  March,  1916. 
Male  examined  and  measured  in  a  living  condition ;  female  fixed  in  Flemming's 
solution  and  soon  after  examined  and  measured  in  water.  The  form  of  the 
pharynx  and  oesophagus;  the  presence  of  special  tubular  setae;  the  structure 
of  the  spinneret,  and  the  relatively  small  number  of  annules,  seem  to  indicate 
a  closer  relationship  of  Greeffiella  with  Desmoscolex  than  has  been  hitherto 
imagined.  Perhaps  Greeffiella  should  be  placed  in  the  same  family  with 
Desmoscolex,  Tricoma,  etc. 


An  Amendation 

of 
HOPLOLAIMUS  DADAY  1905  nee  auctores 

CONTRIBUTIONS  TO  A  SCIENCE  OP  NEMATOLOGT,  XIII 
BY  N.  A.  COBB 

In  1905  Daday  proposed  the  new  genus  Hoplolaimus  on  the  basis 
of  a  single  female  nema  from  soil  in  Paraguay. 

Hoplolaimus  was  so  imperfectly  characterized  that  numerous 
subsequent  authors  have  referred  to  it  a  variety  of  species  that  seem 
certain  not  to  belong  to  it,  in  the  light  of  recent  discoveries  now  to  be 
described. 

Hoplolaimus  Daday  1905  amend. 

Coarsely  annuled  typical  tylenchidae  with  a  prominently  set  off,  lobed 
lip-region  composed  of  several  annules,  and  an  onchium  with  more 
or  less  lobed  basal  bulbs,  -f-  and  -m.  Males  with 
lobed  bursa  encompassing  the  tail. 

iL  _  ^8  -I2--  _  ~  56- ~_  !8-_i 

H.  coronalus  n.  sp.  ?••-.*  2-^~A'  '  3.3  2.4  L 
The  transparent  colorless  layers  of  the  naked  cuticle 
are  traversed  by  plain,  transverse  striae,  all  alike, 
about  three  microns  apart  and  easy  of  resolution,  which 
are  not  further  resolvable,  and  which  are  altered 
materially  on  the  lateral  fields  by  the  presence  of 
three  longitudinal  wings,  occupying  a  space,  measured 
midway  on  "the  nema,  one-third  as  great  as  the  width 
of  the  body.  The  optical  expression  of  these  wings  the  right  laterai^horci  of  the 
consists  of  four  parallel  lines,  of  which  the  two  outer  interesting  u^pai'red^pheroi- 
are  rather  distinctly  crenate,  while  the  two  inner,  fd0aurtTaPshiS\s0thaenbod^ 
occupying  a  little  less  than  a  third  of  the  wing  space,  having  connections  fore  and 
connect  with  refractive  cuticular  alterations  of  the  Se^gSfnffiSLrf 
striae,  which  thus  give  rise  to  a  rather  distinct  more  niicronrsacrdos8neaseeirabove8 
or  less  quadrangular  network  on  the  lateral  fields. 
On  the  neck  the  wings  become  reduced  to  two.  The  cuticle,  about  two  and 
one-half  microns  thick,  is  striated  internally  as  well  as  externally.  As  usual, 
the  annules  close  to  the  lip  region  are  somewhat  narrower  than  those  farther, 
back.  From  somewhat  behind  the  anus  the  final  striae  on  the  tail  of  ithyei 
female  make  a  gradually  smaller  angle  with  the  lateral  line  and  finally  encircla 
the  terminus  in  the  lateral  plane.  Very  slightly  oblique  longitudinal  striae,! 
due  to  the  attachment  of  the  musculature,  are  visiblenin:  mast  regions  of- the 
body.  There  are  no  dermal  appendages  and: no '.series /of  pores-has  beea! 
seen  in  the  cuticle,  but  there  is  an  unpaired  lateral  organ  ©a  bexfch  the  female 
and  male.  (See  Fig.  1.)  The  cylindroid  neck  becoihes  coaVex-conoid  at  the 
rounded  head,  which  is  continuous ;ancj  presents  a  central  mouth,  opening  oiily> 
very  slightly  depressed.  The  lip  region  however  is  a  flat/  blimtisk;  cone,  about 
twenty  microns  broad  by  eight  mieroos  Jiighjlit  !&>aefc  apart ;by  a  v&ry\distincb 

363 


364 


HOPLOLAIMUS 


M3S- 


reglb. 


kblblG) 


, 
WMoii  Wsubnmh  x500 


Fid.  2.  An  oblique 
dcrso-ventral  view  of 
head  of  H.  coronatus  n. 
sp.  The  quadrangular 
nature  of  the  cap  is 
shown  in  the  front  view, 
above. 


constriction  so  that  it  constitutes  a  sort  of  cap  on  the 
front  of  the  head.  This  somewhat  quadrate  cap  is  longitudi- 
nally faintly  six-lobed  and  each  lobe  is  again  longitudinally 
as  well  as  transversely  subdivided.  See  Fig.  2.  The  lip 
region  of  the  male  is  like  that  of  the  female  except  that 
it  is  more  nearly  hemispheroid,  that  is,  relatively  higher 
and  slightly  larger.  There  is  a  rather  robust  six-ribbed, 
yellowish,  dome-like  structure  as  the  framework  of  the  lip- 
region,  through  it  is  obscured  by  the  nature  of  the  cuticular 
covering.  This  framework  extends  a  little  back  of  the 
labial  constriction  and  its  yellow  color  becomes  more  evi- 
dent here.  See  Fig.  3.  Needless  to  say,  therefore,  the 
amalgamated  lips  are  fixed,  and  shut  closely  around  the 
anterior  extremity  of  the  onchium.  Whether  the  lip  region 
is  innervated  remains  unknown,  but  no  innervations  have 
been  seen.  The  tylenchoid  pharynx  is  of  a  very  robust  na- 
ture and  reminiscent  of  that  of  Nemonchus.  The  base  of 
the  onchium,  or  spear,  thirteen  microns  wide  by  ten  high,  is 
very  distinctly  three  bulbed  and  is  about  one-fifth  as  wide  as 
the  corresponding  portion  of  the  head.  Each  of  the  three 
bulbs  is  anteriorly  somewhat  lilobed,"  presenting  sometimes 
two  and  sometimes  three  rather  distinct  forward  pointing 
knobs.  Owing  to  its  index  of  refraction  this  lobed  base  of 
the  onchium,  as  well  as  the  "hilt,"  are  almost  totally  invisible  in  balsam  mounts; 
while  the  acute  tapering  anterior  part  remains  distinctly  visible, — another 
evidence  of  the  two-fold  character  (and  origin)  of  the  tylenchoid  onchium. 
The  posterior  attachment  of  the  musculature  comprising  the  ellipsoidal 
pharyngeal  bulb,  which  is  one-half  as  wide  as  the  head,  is  not  only  to  the  front 
portion  of  the  bulbs  of  the  onchium  but  also  to  their  posterior  surfaces.  The 
hilt  is  about  half  as  wide  as  the  bulbous  base;  the  anterior  end  of  the  spear  is 
blunt,  and  the  lumen  relatively  unusually  narrow; — all  which  makes  the  spear 
an  unusually  substantial  structure,  capable  of  puncturing  tissues  offering  con- 
siderable resistance.  In  harmony  with  this,  the  ellipsoidal  to'obpyriform 
spear  guide  is  of  strong  construction,  consisting  in  part  of  six  outwardly  bowed 
elastic  elements  surrounding  the  anterior  third  of  the  spear  and  springing  back- 
ward from  the  base  of  the  cutinized  lip  region.  (Figs.  2  and  3.)  This  six-fold 
spear  guide  has  a  variable  length  and  width,  its  form  changing  with  the  atti- 
tude of  the  spear; — when  at  rest,  with  a  length  of  fourteen  microns,  its  width 
is  about  eight  microns, — that  is,  it  is  about  one-third  as  wide  as  the  correspond- 
ing portion  of  the  head.  In  addition  to  this  spear  guide  the  cutinized  lip- 
region  fits  closely  around  the  anterior  portion  of  the  spear  for  a  considerable 
distance.  Both  the  spear  and  the  spear  guide  appear  to  present  traces 
of  transverse  striation  corresponding  in  fineness  with  the  minute  subdivisions 
of  the  annules  sometimes  visible  in  the  subcuticle.  The  two  parts  of  the 
spear  are  rather  distinctly  set  off  from  each  other  by  a  very  fine  transverse 
junction  mark,  as  in  many  Tylenchi.  No  amphids,  deirids  or  phasmids  have 
been  seen.  There  are  no  eyespots.  The  oesophagus  is  tylenchoid,  presenting 
however,  as  already  indicated,  a  rather  distinct  pharyngeal  bulb,  something 
rather  uncommon  in  the  Tylenchidae.  The  spherical  or  oblate  median  oeso- 
phageal  bulb  is  half  as  wide  as  the  corresponding  portion  of  the  neck,  and  is  set 
off  both  fore  and  aft  from  the  remaining  narrow  portions  of  the  oesophagus, — • 
very  abruptly  behind  and  rather  abruptly  in  front.  Behind  the  median  bulb 
the  narrow  oesophagus  gradually  enlarges  to  form  a  rather  obscure  posterior 


HOPLOLAIMUS  365 

long-clavate  swelling  which  at  its  widest  part  is  one-fourth  as  wide  as  the  base  of 
the  neck.  It  is  however  natural  to  imagine  the  swollen  salivary  glands  to  be 
joined  with  this  inconspicuous  posterior  portion  of  the  oesophagus  and  thus  at 
first  to  get  an  idea  that  the  posterior  part  of  the  oesophagus  comprises  a  wide 
clavate  swelling,  three-fourths  as  wide  as  the  base  of  the  neck.  We  may  say 
therefore  that  the  oesophagus  behind  the  pharynx  is  about  one-seventh,  at  the 
nerve-ring  also  about  one-seventh,  and  finally  about  one-fourth  as  wide  as  the 
corresponding  portion  of  the  neck.  The  lining  of  the  oesophagus  is  a  distinct 
feature  arteriorly  and  consists  of  a  narrow  highly  refractive  tube;  posteriorly 
the  lining  is  inconspicuous.  The  musculature  is  fine  and  colorless.  There  are 
three  salivary  glands  clustered  opposite  the  posterior  two-fifths  of  the  oesopha- 
gus. One  of  these  cells  comprises  the  anterior  portion  of  the  cluster,  while  the 
other  two  may  lie  more  or  less  opposite  each  other  as  the  posterior  part. 
The  salivary  glands  are  very  well  developed,  and  two  of  them, 
submedian,  empty  through  ducts  into  the  base  of  the  valve  of 
the  median  bulb,  while  the  third,  the  dorsal,  passes  forward  and 
empties  into  the  dorsal  side  of  the  oesophageal  lumen  not  far 
behind  the  base  of  the  onchium.  At  the  mouth  of  each  duct 
a  faint  ampulla  is  usually  visible.  The  median  oesophageal 
bulb  presents  a  spheroidal,  simple,  strongly  refractive 
valve  one-sixth  as  wide  as  the  bulb  itself.  There  is  no 
distinct  cardia.  The  thick-walled  intestine,  which  presents 
a  distinct  refractive  lumen,  is  not  set  off  from  the  oesoph- 
agus by  a  cardiac  collum,  the  change  from  oesophagus  to 
intestine  being  gradual.  The  intestine  has  its  cells  closely 
packed  with  granules  of  variable  size,  the  largest  being 
one-twelfth  to  one-sixteenth  as  wide  as  the  body.  These 
colorless,  non-birefringent,  spherical  granules  gradually  de- 
crease in  number  in  the  cardiac  region  and  cease  altogether 
opposite  the  posterior  portion  of  the  salivary  glands;  they  are 
sometimes  so  arranged  as  to  give  rise  to  a  tessellated  effect.  erf,IGvigW  H  c 
The  intestine  somewhat  gradually  becomes  four-fifths  as  wide  natus  n  sp  Beiow> 
as  the  body,  and  is  composed  of  cells  of  such  a  size  that  two  to  a  semi-contour  of  the 
three  are  presented  in  each  cross  section.  The  cells  of  the  body  in  the  same 
intestine  are  so  closely  packed  with  granules  as  to  make  it  JJJ££  ^fn°gwin* 
difficult  to  examine  successfully  in  living  specimens  details 
of  the  anatomy  of  adjacent  organs.  The  exceedingly  small 
anus  and  the  rectum  are  very  inconspicuous.  There  is  no  pre-rectum.  The  tail 
is  of  an  elongate  hemi spheroid  form,  very  broad  and  rounded  at  the  extremity, 
and  symmetrical.  There  is  no  spinneret  and  there  are  no  caudal  glands. 
Measured  at  the  latitude  of  the  nerve-ring,  the  lateral  chords  are  as  wide  as  the 
cuticle  is  thick,  or  wider;  somewhat  farther  back,  they  are  about  one-third  as 
wide  as  the  body.  They  contain  scattered  colorless  refractive  spherical  gran- 
ules of  variable  size,  considerably  smaller  than  those  of  the  intestine.  Behind 
the  base  of  the  neck,  at  a  distance  about  equal  to  the  diameter  of  the  body, 
there  is  a  cell  which  presses  the  intestine  well  to  one  side.  This  cell  is  about 
as  long  as  wide  but  not  spheroidal.  It  is  finely  granular,  one-half  as  wide  as 
the  body,  and  seems  very  probably  to  be  connected  with  the  renette.  The 
excretory  pore,  which  is  opposite  the  base  of  the  neck,  is  rather  distinctly  to  be 
seen,  though  of.  small  size.  It  lies  between  two  annules,  and  the  nearer  stria- 
tion  may  bend  a  little  to  one  side  for  it.  The  renette  duct  leads  inward  and  to 
the  right  alorg  the  right  lateral  chord.  From  the  somewhat  depressed,  rather 
large  and  rather  conspicuous  vulva,  which  is  a  transverse  slit  two-fifths  as  long 


366 


HOPLOLAIMUS 


as  the  body  is  wide,  the  strongly  cutinized  medium  sized  vagina  extends  inward 
at  right  angles  to  the  ventral  surface  half  the  way  across  the  body.  From  to- 
ward the  ends  of  the  valvular  open- 
ing four  muscles  pass  obliquely  to 
the  ventrally  submedian  regions 
of  the  body,  two  forward  and 
two  backward, — two  to  the  right 
and  two  to  the  left.  Furthermore 
there  are  two  transverse  valvular 
muscles  attached  near  the  ends 
of  the  opening  and  fanning  out 
to  the  lateral  parts  of  the  body 
wall,  one  right  and  the  other 
left,  each  partially  encircling  the 
intestine.  Each  of  the  two  out- 
stretched uteri,  about  two  body- 
widths  long  and  about  one-fourth 
as  wide  as  the  body,  at  its  distal 
extremity  presents  a  spermatheca 
three-fourths  as  wide  as  the  body, 
sometimes  containing  what  appear 
to  be  toward  one  hundred  sausage 
shaped  sperm  cells  each  some- 
times having  a  bunch  of  chromo- 
somes at  ode  end .  These  sperma  - 
theca  are  located  at  a  distance 
from  the  vulva  two  or  three  times 

as  great  as  the  diameter  of  the  body.  In  the  late  autumn  they  are  a  very  uni- 
form feature  of  the  adult  females  which  have  deposited  no,  or  very  few,  eggs. 
As  thus  far  seen,  the  slender  outstretched  ovaries  are  about  one-fourth  as  wide 
as  the  body;  both  lie  on  the  left  side.  They  are  narrow  and  somewhat  cylin- 
droid  and  contain  one  hundred  or  more  ova  arranged  somewhat  irregularly. 
The  male  is  like  the  female  in  form.  The 


Fio.  4.  Lateral  and  ventral  views  of  the  tail  end  of  the 
male  of  Hoplolaimus  coronalvs  n.  sp.  Treated  with  potas- 
sium hydrate  to  obliterate  non-cutinized  structures. 


3.4       8.9  _  13.         — M  97.3 

spicula  are  colorless.    A  portion  of  the  —  - — 2~s^~3~2. T5~  ~~~^2~2       " 

gubernaculum  lies  ventrad. — (telamon  of    " 

Hall).  See  Fig.  4.  There  are  no  preanal  ventral  supplementary  male 
organs,  and  no  ribs  occur  in  the  bursa.  The  striae  of  the  bursa  on  the 
ventral  side  are  less  distinct  near  the  ventral  line.  The  terminal  lobe  of 
the  bursa  appears  destitute  of  striation;  if  any  striae  are  present  they 
must  be  exceedingly  fine.  The  vas  deferens  appears  to  be  about  one-half  as 
wide  as  the  body.  The  narrow  cylindroid  testis  tapers  a  little,  and  at  the  blind 
end  is  only  one-fourth  as  wide  as  the  body.  The  granular  sperm  cells  seen  in 
the  vas  deferens  are  about  one-tenth  as  wide  as  the  body;  the  spermatocytes, 
farther  forward,  one-eighth. 

Habitat:  Found  in  soil  immediately  about  a  Mermis  "nest,"  (Agamermis 
decaudatd),  Four  Mile  Run,  Falls  Church,  Va.,  U.S.A.  Nov.,  1922. 

The  movements  of  this  nema  are  very  slow.  The  limber  body  readily  takes 
on  sharp  sigmoid  curves  and  is  sometimes  seen  coiled;  in  fact  the  males  can 
coil  rather  closely.  From  this  amended  characterization  it  seems  evident 
the  Hoplolaimus  Daday  (not  of  other  authors)  is  a  rather  clearly  marked 
genus.  A  close  relative  of  Hoplolaimus  is  Dolichodorus  Cobb  1914. 


NOTES  ON  PARATYLENCHUS,  A  GENUS  OF  NEMAS 

BY  N.  A.  COBB 

Contributions  to  a  Si  ience  of  Nematology,  XIV. 

The  following  paragraphs  contain  new  information  with  regard  to 
the  lip  region,  vestibule,  spear  guide,  structure  of  the  spear,  median 
oesophageal  bulb,  salivary  glands,  deirids  (cervical  papillae),  renette, 
eggs  and  their  deposition,  and  gonism  of  Paratylenchus  Micoletsky. 


.       -    .  fl 

Paratylenchus  nanus  n.  sp.  3.7  4.3  /  4,j  4.2  2.  The  trans- 

parent, colorless,  naked  cuticle,  about  1.5  microns  thick,  is  traversed  by  plain, 
transverse  striae,  2.0  microns  apart  except  near  the  extremities,  all  alike  and 
fairly  easy  of  resolution,  which  are  materially  altered  on  the  lateral  fields  by 
the  presence  of  wing  regions,  about  one-seventh  as  wide  as  the  body,  beginning 
on  the  neck  and  ending  on  the  tail.  The  optical  expression  of  the  wings  on 
living  specimens  usually  consists  in  four  parallel  longitudinal  lines  on  each 
lateral  field,  the  two  outer  of  which  are  fainter  than  the  two  inner.  Very 
slightly  oblique  longitudinal  striae  of  the  subcuticle,  all  alike,  due  to  the 
attachment  of  the  musculature,  are  rather  easily  to  be  seen  in  nearly  all  regions 
of  the  body.  The  contour  of  the  body  is  crenate  or  very  faintly  serrate- 
crenate.  There  are  no  dermal  appendages  and  there  are  no  series  of  pores  to 
be  seen  in  the  cuticle.  On  the  neck  opposite  the  excretory  pore,  lat.  22.2,* 
there  is  a  papilla  on  each  lateral  line,  and,  leading  inward,  ventrad  and  slightly 
backward  from  the  middle  of  each  papilla  is  an  obscurely  sinuous  element 
connecting  with  the  nervous  system.  These  organs  are  believed  to  be  deirids. 

The  neck,  which  is  cylindroid  posteriorly,  and  to  a  considerable  extent  also 
anteriorly,  becomes  decidedly  convex-conoid  farther  forward,  and  ends  in  a 
rounded  or  subtruncate,  continuous  head  compassing  about  thirty  annules 
of  the  cuticle,  which  presents  a  somewhat  depressed,  very  minute,  central 
mouth  opening,  closely  surrounded  by  six  equal,  exceedingly  minute  lips.  The 
truncation  of  the  head  occurs  at  the  lip  region,  which  has  at  this  point,  that  is 
at  the  anterior  extremity  of  the  nema,  a  width  of  about  two  microns.  The  lip 

*  The  Word  "Latitude"  in  Descriptive  Nematology.  I  have  lately  come  to  use  the 
word  "latitude"  in  a  conventional  sense  in  dealing  with  nema  anatomy,  and  find  it  so 
useful  as  to  lead  to  this  attempt  more  accurately  to  define  the  word  as  thus  used. 

The  meaning  of  latitude  in  this  connection  arises  from  geographical  usage,  but  in 
nematology  the  term  applies  to  a  transverse  plane  or  section  of  the  organism,  and  not  to 
a  circle  on  the  surface  only,  as  in  geography,  and  it  has  not  seemed  desirable  to  have  two 
sorts  of  latitude,  such  as  north  and  south. 

One  hundred  degrees  of  latitude  is  assumed,  with  zero  at  the  anterior  extremity  of 
the  organism.  Thus  an  element  of  the  organism  in  latitude  50  would  be  at  the  middle; 
and  in  latitude  100  at  the  end  of  the  tail.  The  terms  can  be  abbreviated.  Thus:  lat.  60. 

In  the  case  of  nemas,  which  are  so  nearly  round  in  cross  section,  a  similar  use  of  the 
word  "longitude"  sometimes  becomes  useful,  the  ventral  line  being  taken  as  zero. 

The  conventional  use  of  the  words  latitude  and  longitude  in  this  way  is  more  or  less 
"logical",  and  very  easily  acquired,  and,  according  to  my  experience,  is  a  decided  saving 
in  time  and  space,  and  has  the  merit  of  definiteness,  as  well  as  brevity. 


368  PARATYLENCHUS 

region  is  supported  by  a  faintly  visible  six-ribbed,  refractive,  somewhat  dome- 
shaped,  cuticular  framework,  six  to  seven  microns  across  at  the  base,  and 
about  two-thirds  as  "high"  as  it  is  wide.  The  more  or  less  immobile  lips  are 
usually  closed. 

There  is  a  small  combined  vestibule  and  spear  guide,  about  as  wide  as  the  lip 
region  and  some  ten  microns  long,  more  or  less  visible  on  account  of  the  refrac- 
tive nature  of  its  elements.  This  portion  of  the  labial  structure  has  for  one  of 
its  main  functions  the  guidance  of  the  spear  when  in  action.  The  vestibular 
part  is  about  four  microns  deep  and  varies  somewhat  in  diameter  according  to 
the  attitude  of  the  lips  and  spear.  Leading  backward  from  the  base  of  the 
vestibule  there  is  a  symmetrical  set  of  outwardly  bowed,  somewhat  flexible, 
rather  slender,  longitudinal  elements  constituting  the  main  portion  of  the  spear 
guide.  The  relatively  very  robust  spear  is  about  twice  as  long  as  the  base  of 
the  head  is  wide.  It  ends  posteriorly  in  a  distinctly  three-lobed  expansion 
toward  one-third  as  wide  as  the  base  of  the  head,  the  dorsal  lobe  being  slightly 
farthest  back,  and,  sometimes  at  least,  presenting  a  dorso-posterior  condyle. 
It  is  somewhat  behind,  and  in  a  line  with,  the  axil  of  the  dorsal  lobe  that  the 
dorsal  salivary  gland  empties  into  the  oesophageal  lumen.  The  spear  often  tapers 
more  or  less  regularly  throughout  its  length;  nevertheless  there  is  a  distinct 
basal  part,  comprising  about  two-fifths  of  the  whole,  set  off  by  a  minute  but 
distinct  junction  mark,  and  averaging  about  one-sixth  as  wide  as  the  corre- 
sponding portion  of  the  head.  At  its  distal  end  the  spear  is  exceedingly  finely 
pointed.  Well  developed  muscles  for  the  protrusion  of  the  spear  are  readily 
seen  and  often  lie  rather  close  to  the  spear, — not  forming  any  very  marked 
swelling  when  at  rest.  Anteriorly  there  are  six  of  these  muscles, — one  passing 
to  each  sector  of  the  labial  framework. 

No  amphids  have  been  seen.     There  are  no  eyespots. 

The  oesophagus  is  tylenchoid  and  presents  a  very  definite,  somewhat  pine- 
apple-shaped, non-muscular,  valueless  cardiac  swelling,  half  as  wide  as  the  base 
of  the  neck.  The  very  long,  large,  rather  ob-clavate,  median  swelling,  which  is 
two-thirds  as  wide  as  the  middle  of  the  neck,  is  set  off  abruptly  behind,  but  is 
decurrent  in  front  and  reaches  to,  and  somewhat  includes,  the  base  of  the 
onchium;  in  its  posterior  part  it  presents  a  well-developed,  elongated-fusiform, 
triplex  valve,  occupying  one-third  of  the  diameter,  to  which  are  attached  the 
usual  radial  muscles  for  the  opening  of  the  valve  in  the  act  of  swallowing.  An 
interesting  peculiarity  of  the  median  swelling  is  that  the  contained  robust 
tubular  oesophageal  lining,  which  is  disposed  in  a  single  loop  or  coil  when  at  rest, 
takes  on  this  attitude  without  much  disturbance  to  the  evenness  of  the  contour  of  the 
swelling  itself,  thus  showing  the  "clavate  swelling"  to  be  a  distinctly  two-fold 
affair, — partly  (posteriorly)  muscular,  and  partly  (dorsally  throughout)  gland- 
ular, and  with  the  two  tissues  so  little  connected  that  the  glandular  part  is 
comparatively  separate  and  responds  but  little  to  the  movements  of  the  tubu- 
lar lining.  Ordinarily  one  would  expect  the  anterior  narrower  part  of  such  a 
long  median  swelling  to  curve  or  coil  along  with  the  lining.  Though  the 
limits  of  the  true  median  bulb  (not  the  clavate  swelling  but  the  included 
median  bulb  more  properly  speaking),  are  of  ten  somewhat  indefinite  anteriorly, 
it  may  properly  be  described  as  ellipsoidal,  two-thirds  as  wide  as  the  neck  and 
two  and  one-half  times  as  long  as  wide;  in  other  words  the  entity  of  the  median 
muscular  bulb  is  not  entirely  lost.  Behind  the  pharynx  the  oesophagus  is  one- 
sixth,  at  the  nerve  ring  only  about  one-tenth,  in  front  of  the  cardiac  swelling 
about  one-eighth,  and  finally  one-half,  as  wide  as  the  corresponding  portion  of 
the  neck.  The  lining  of  the  oesophagus  is  tubular  and  narrow,  and  distinct 
except  in  the  posterior  glandular  bulb, — most  distinct  in  the  clavate  swelling. 

There  are  well  developed  salivary  glands.  The  nucleus  of  one  of  these  organs 
may  be  seen  in  the  dorsal  sector  of  the  cardiac  swelling,  as  already  described,— 


PAFATYLENCHUS 


369 


dorsad  and  occupying  the  major  part  of  it, — and  emptying  into  the  oesoph- 

rl  lumen  near  the  onchium.     It  is  doubtful  if  salivary  secretion  passes 
into  the  base  of  the  fusiform  median  valve,  though  there  seem  to  be  two 
subordinate  nuclei  in  the  cardiac  swelling. 

There  is  no  cardia.  The  thick  walled  intestine,  set  off  by  a  rather 
faint  cardiac  collum  one-half  as  wide  as  the  base  of  the  neck,  presents  a 
faint,  though  fairly  capacious  lumen.  It  is  composed  of  cells  of  such  a  size 
that  probably  only  about  two  are  presented  in  each  cross  section.  It  becomes 
at  once  two-thirds  as  wide  as  the  body.  From  the  very  inconspicuous,  con- 
tinuous anus,  the  rectum,  which  is  also  very  inconspicuous,  extends  inward 
and  forward.  There  is  no  distinct  pre-rectum.  The  numerous,  colorless 
granules  found  in  the  cells  of  the  intestine,  the  largest  of  which  are  about  one- 
tenth  as  wide  as  the  body,  namely  about  two  microns  in  diameter,  are  not  so 
arranged  as  to  give  rise  to  a  tessellated  effect.  Sometimes  the  cells  throughout 
the  intestine  are  uniformly  filled  with  granules ;  more  often  the  granules  are 
absent  here  and  there,  so  as  to  create  a  "segmented"  effect. 

The  tail,  which  compasses  about  twenty  annules  of  the  cuticle,  is  conoid, 
subarcuate,  and  tapers  from  in  front  of  the  anus  to  the  rather  blunt,  or  some- 
times subacute,  unarmed,  symmetrical  terminus.  There  is  no  spinneret. 
There  are  no  caudal  glands  and  there  are  no  caudal  setae. 

Apparently  the  lateral  chords  are  about  one- 
third  as  wide  as  the  body.  The  rather  prominent 
excretory  pore  is  located  just  behind  the  nerve  ring 
and  the  excretory  duct  can  be  followed  inward  and 
backward  along  the  right  lateral  chord  at  least  as 
far  as  the  middle  of  the  body. 

The  nerve  ring  is  oblique,  of  medium  size  and 
accompanied,  fore  and  aft,  by  numerous  nerve  cells, 
some  of  which  lie  as  far  forward  as  opposite  the 
middle  of  the  median  oesophageal  swelling. 

The  single  female  sexual  organ  is  outstretched 
forward.  From  the  unusually  large,  depressed  and 
very  conspicuous  vulva,  the  vagina,  which  is  large, 
extends  inward  obliquely  forward,  three-fourths  the 
distance  across  the  body.  Its  walls  are  rather 
strongly  cutinized.  The  larger  anterior  lip  of  the 
vulva  may  be  slightly  elevated.  The  body  of  the 
nema  decreases  a  little  in  diameter  rather  suddenly 
at  the  vulva  and  tapers  more  rapidly  thence  back- 
ward. The  thin-shelled,  smooth,  elongated  egg  is 
nearly  thrice  as  long  as  the  body  is  wide  and  meas- 
ures about  60  x  20  microns.  Only  one  egg  occurs  in 
the  uterus  at  a  time.  A  prolate  compact  mass  of 
sperm  cells,  often  comprising  some  two  to  five  hun- 
dred minute,  spherical,  refractive  elements,  occurs 
regularly  in  the  uterus  of  newly  adult  females;  this 
sperm  mass  is  often  two-thirds  to  three-fourths  as 
wide  as  the  body.  From  the  formation  and  size  of 
the  sperm  cells  it  is  concluded  that  the  species  is 
syngonic.  No  males  have  been  seen  among  about 
fifty  females,  many  gravid,  from  two  North  Ameri- 
can regions.  The  medium  sized  ovary  is  usually 
cylindroid  posteriorly,  and  tapers  anteriorly;  it  aver- 
ages to  be  about  one-third  as  wide  as  the  body. 
Toward  fifty  ova,  arranged  for  the  most  part  sin- 
gle file,  are  to  be  seen  in  the  ovary.  There  is  prac- 
tically no  post-vulvar  rudiment  of  a  sexual  organ. 


grnmt; 


1.  Anterior  part  of  a 
Paratylenchus  nanus. 


370  PABATYLENCHUS 

There  are  two  or  three  somewhat  ellipsoidal  organs,  half  as  wide  as  the  body, 
about  two-thirds  as  wide  as  long,  located  just  behind  the  base  of  the  neck,  and 
closely  associated  with  the  beginning  of  the  intestine.  These  regularly  darken 
in  Flemming's  solution  and  are  as  yet  of  unknown  significance. 

Habitat:  Found  in  soil  about  the  roots  of  grasses,  Devil's  Lake,  North 
Dakota,  April,  1915;'  and  Four  Mile  Run,  Falls  Church,  Va.,  August,  1922. 
Flemming's  solution  to  glycerine  jelly.  In  many  respects  this  species  closely 
resembles  Tylenchus  macrophallus  de  Man,  but  differs  in  the  following  particu- 
lars;— the  spear  is  somewhat  longer  and  possibly  somewhat  more  robust;  the 
striation  is  coarser;  the  body  is  wider;  the  tail  of  nanus  compasses  twenty 
annules  while  that  of  macrophallus  appears  to  compass  about  fifty;  opposite  the 
spear  in  nanus  there  are  about  twenty-five  to  thirty  annules,  while  in  macro- 
phallus  there  appear  to  be  about  forty.  Should  opportunity  occur  it  would 
perhaps  be  advisable  to  re-examine  the  median  oesophageal  region  of  macro- 
phallus.  For  the  present  at  least  it  seems  best,  unless  the  undiscovered  male 
of  nanus  should  prove  to  be  extraordinarily  like  the  male  of  macrophallus,  to 
regard  the  two  species  as  distinct.  Paratylenchus  is  related  to  the  very  well- 
defined  genus  Iota,  a  genus  whose  numerous  representatives  typically  are 
minute,  very  short,  very  broad,  coarsely  annuled,  rather  inflexible  nemas 
found  in  acid  soils,  and  having  the  single  outstretched  female  sexual  organ 
emptying  through  a  vulva  located  very  close  to  the  minute,  inconspicuous  anus 
and  often  possessing  external  coarse  retrorse  cuticular  elements, — ridges,  scales, 
spines,  fringes,  etc.,  according  to  the  species.  There  is  a  number  of  as  yet 
unpublished  species  of  which  it  is  not  easy  to  make  a  satisfactory  assign- 
ment as  between  Iota  and  Paratylenchus.  The  unknown  males  of  nanus,  if 
such  exist,  may  be  expected  to  throw  more  light  on  the  generic  relationships. 
P.  nanus  may  be  synonymous  with  P.  bukowinensis  Micoletzky,  1922. 

."•.    .*:  »,  A1-  .   ~8>.    .  9?-  .  0>36.. 

4-8      5^i '",  5.6          5.1         3.1  are  the  measurements  of  a  living  specimen 

of  P.  nanus  under  slight  pressure  and  therefore  a  little  flattened,  and  further- 
more showing  a  neck-length  unaltered  by  fixation  and  preservation. 

24.         28.   __  34.  Y  92.6<?> 

Paratylenchus  ancepsn.  sp.  5-3  5.3  /5.J  4.6  3.6  '  "  P.  anceps  so 
closely  resembles  P.  nanus  that  only  the  differences  need  be  here  noted.  The 
striae  are  one  micron  apart.  The  optical  expression  of  the  wings  is  a  pair  of 
refractive  parallel  lines  whose  distance  apart  is  about  equal  to  the  width  of 
two  annules  of  the  cuticle.  The  conoid  neck  becomes  convex-conoid  at  the 
head,  at  the  front  of  which  the  lip  region  is  about  four  microns  wide.  The  spear 
guide  is  six  microns  long,  and  the  spear  about  half  as  long  as  the  neck,  the 
long  slender  anterior  part  comprising  three-fourths  or  four-fifths  of  the  whole. 
The  three-lobed,  flattish  basal  bulb  of  the  spear  is  about  one-fourth  as  wide  as 
the  corresponding  portion  of  the  neck,  that  is  about  four  microns  wide.  The 
somewhat  elongated-pyriform  or  pineapple-shaped  posterior  bulb  is  three- 
fifths  as  wide  as  the  base  of  the  neck.  The  deirids  are  near  the  base  of  the 
neck.  The  tail  is  slightly  conoid  to  the  broad,  rounded  terminus,  which  is 
half  as  wide  as  the  base  of  the  tail.  The  vulva  was  about  to  appear  at  the 
same  relative  position  as  in  P.  nanus.  In  all  other  respects  almost  precisely 
as  in  P.  nanus. 

Habitat:  Roots  of  Umbellularia  californica,  Riverside,  California,  1912. 


BIOLOGICAL  RELATIONSHIPS  OF  THE  MATHEMATI- 
CAL SERIES  1,2,  4,  ETC. 

WITH  A  DESCRIPTION  OP  A  NEW  NEMA,  TYLENCHUS  CANCELLATUS 
Contributions  to  a  Science  of  Nematology.   XV 

BY  N.  A.  COBB 

The  behavior  of  the  components  of  matter,  e.g.,  in  chemical  reactions, 
appears  to  compel  discontinuous  variation  in  the  evolution  of  organisms. 
Organic  evolution  has  been  thought  continuous,  but  mutation  now  suggests 
that  it  is  discontinuous.  Must  it  not  necessarily  be  discontinuous1  from  the 
very '  nature  of  the  composition  of  matter?  Morphological  changes  in 
organisms  originate  in  chemical  changes  in  the  matter  of  which  they  are 
composed.  Now,  a  chemical  change  is  one  that  either  takes  place  or  does 
not  take  place;  nothing  intermediate  is  known.  Hence  it  seems  that  the 
fundamental  changes  in  the  evolution  of  organisms,  so  far  as  we  can  conceive 
at  present,  i.e.,  chemical  changes,  must  be  saltatory.  But  we  cannot  con- 
ceive of  the  greater  and  obvious  (visible)  changes,  except  as  summations  of 
these  minute  changes.  The  visible  changes  then  must  per  force  be  con- 
sidered of  the  same  character  as  that  of  their  components,  i.e.,  all  visible 
evolutionary  changes  in  organisms  must  be  of  a  saltatory  nature. 

The  mathematics  of  the  morphology  of  organic  evolution  may  therefore 
be  considered  as,  at  least  mainly,  discontinuous, — -arithmetical. 

The  material  basis  of  life  is  discontinuous,  but  is  the  only  known  form  of 
matter  so  organized  as  to  grow  and  multiply  by  assimilation;  in  this  lies  the 
fundamental  difference  between  living  objects  and  all  others; — not  a  mathe- 
matical difference. 

Matter  is  dualr  or,  less  abstractly,  there  exists  in  matter  an  exceedingly 
widespread,  probably  universal,  "bipolarity",  exemplified,  therefore,  in  organ- 
isms. The  universality  of  "bipolarity"  is  more  or  less  understood  and 
generally  admitted.  Its  universality  might  be  assumed  to  prove,  and  at 
least  very  strongly  suggests,  its  necessity.  Assuming  its  necessity,  this 
bipolarity  determines  that  cells,  as  well  as  many  of  their  components,  multi- 
plying, do  so  by  binary  division  in  a  bipolar  manner.2 

1  Mathematics.     Arithmetic  and  its  derivatives  arose  through  everyday  problems 
connected  with  matter,  which  is  discontinuous.     The  Calculus,  mathematics  of  con- 
tinuity, arose  through  problems  like  those  of  astronomy,  where  the  continuity  of  space 
and  time  impress  us  most  vividly. 

Quantity.  It  may  be  said  we  cannot  conceive  of  anything  so  small  that  it  cannot  be 
divided,  or  so  large  that  nothing  can  be  added  to  it ;  but  as  the  two  opposite  statements 
seem  just  as  true,  we  find  ourselves  within  two  limits  at  each  of  which  we  confront  some- 
thing that  must  be  so,  but  can't  be  so.  Between  these  two  irrationalities  lie  quantities 
we  can  handle  rationally  by  mathematics. 

2  Thence  "fore-and-aftness"  and  bilateral  symmetry  in  organisms  arose  (doubtless 
modified  by  gravity).     Bilateral  symmetry  seems  the  invariable  result  of  the  growth  of 
what  we  may  call,  for  lack  of  a  better  term,  "untrammeled  protoplasm."     When  proto- 
plasm is  "hampered,"  say  by  inorganic  materials  tending  to  produce  other  forms  of 
symmetry — as,  for  instance,  through  the  laws  of  crystallization — then  bilaterality  may 
be  more  or  less  masked;  otherwise  it  is  manifest.  We  readily  recognize  it  in  nearly  all 
animals  and  plants. 

.371 


372 


TYLENCHUS  CAXCELLATUS 


nirm 


tm  OP 


A  fundamental  result  of  this  phenomenon  is 
that  organisms  thus  become  exact  or  modified 
expressions  of  the  mathematical  series  1,  2,  4,  8, 
16,  etc.,  a  comparatively  unheeded  basic  fact 
worthy  of  careful  attention. 

Is  it  not  possible,  simply  by  way  of  instance, 
/  ///    /  ^Rt  ky  studying  carefully  this  more  or  less 
MPlMDIttu  apparent  widespread  mathematico-biological  ex- 
pression, we  may  reach  a  clearer  understanding 
of  organic  form   and  of  phylogenetic  relation- 
ships?    This  question  suggests  others  of  deeper 
tib  Cfd  import,  since  form  is  largely  an  expression  of  the 
interplay  of  internal  forces. 

Such  a  query  leads  to  counting  and  comparing 
more  carefully  the  various  features  of  organ- 
isms, repetitive  and  otherwise.    Among  a  multi- 
Fig.  i.-Femaie  Tvi-  tude  of  others,  such  questions 

enchus  cancettatus  n.   sp.  .,  •      ,,  .  TITI         •      -j. 

The    characters    are    set    as  this  then  ariSC!   Why  IS  it 
forth  in  the  drawings  and     , ,      ,1,1,1  i  e 

formula.  Above,    front  that    both    the    number    ot 

view  of  head,  followed  by    ,  •.  i      ,  •, 

frm  7  cross-sections  arranged  transverse  annules  and   the 

"'"    about   opposite   the   por-  ,  .    -.  .,      •,•       ,       i 

tions  of  the  body  sec-  number  of  longitudinal  ele- 
ments in  the  cuticle  of 
many  nemas  is  likely  to 
suggest  some  definite 
relationship  to  the  geo- 
metrical series  1,  2,  4,  8, 
16,  etc.?  The  observed 
numbers  are  certainly 
cellular  expressions  of 
the  1,  2, 4  series,  or  vari- 
ants, but  why  and 
according  to  what  law 
is  it  that  very  often 
the  numbers  of  ele- 
ments met  with  are  not 
members  of  the  series 
but  integers  lying 
between?  Why  is 
it  that  chromosome- 
counts  are  suggestive 
of  this  same  mathe- 
matical concept?  And 
so  on  throughout  the 
range  of  organic  struc- 
2  4  -0.5  TOTO  tures.  Are  not  these 


BIOLOGICAL  RELATIONSHIPS  OF  THE   1,  2,  4,   SERIES 


373 


numbers  not  only  necessarily  and  definitely,  but  perhaps  somewhat  simply, 
modified  mathematical  expressions  of  the  fundamental  mathemati co-biologi- 
cal phenomena  inevitably  arising  from  the  fact  that  cells  (as  well  as  some  of 
their  components)  divide  in  accordance  with  the  1,  2,  4  series? 

Variations  of  the  1,  2,  4  series,  as  expressed  in  cell  multiplication,  say  in  a 
segmenting  egg,  can  be  readily  diagrammed.  (See  Fig.  3.)  If  in  such  a  cell- 
division  diagram  any  particular  multiplying  cell  or  cells  be  pictured  as  halted, 
while  the  others  continue  to  divide,  the  next  step  will  bring  about  a  variation 
from  the  geometrical  series.  If  the  reader  will  draw  a  few  simple  diagrams, 
he  will  find  it  easy,  by  such  variations,  graphically  to  represent,  as  existing 
at  successive  early  stages  in  the  imagined  ontogeny,  numbers  of  cells,  say, 
from  1  to  10  inclusive,  and  will  see  that  conceivably  this  could  go  on  indefi- 
nitely, and  that  therefore  any  number  whatever  is  a  possible  biological  variation 
of  the  1,  2,  4  series.  But  this  broadening  of  the  possibilities  must  not  be 
allowed  to  obscure  the  basic  fact  that  the  numbers  are  neverthe- 
less definite  mathematical  variations  of  the  1,2,4  series  due  to  the 
binary  division  of  cells  and  their  components; — -which  in  turn  seems 
compulsory  owing  to  the  nature  of  matter  itself.  Our  problem  seems 
to  be:  Which  of  these  numerous  variations  are  the  more  sig- 
nificant, and  what  are  their  mathematical  and  biological  relationships?  1< 

A  new  triplonch,  Tylenchus  cancellatus  n.  sp.  (Figs.  1  and  2), 
infesting  the  roots  of  peonies,  will  serve,  in  a  very  limited  way,  to 
illustrate  the  foregoing  remarks.  The  figures  (Fig.  1)  show  the 
existence,  near  the  head,  of  sixteen  external  longitudinal  grooves. 
Near  the  middle  of  the  neck  this  number  changes  to  eighteen  by 
the  splitting,  on  each  side  of  the  nema,  of  one  of  the  lateral,  or 
sublateral,  elements  of  the  series,  so  that  most  of  the  body  presents 
18  grooves.  Posteriorly  this  number  reduces  to  14,  10,  then  8. 
(Fig.  1.) 

This  emphasizes  the  value  of  pondering  the  variants  of  the 
1,  2,  4  series.  If  the  numbers  of  the  various  elements  were  con- 
fined to  the  1,  2,  4  series,  they  would  be  less  significant,  hence  less 
useful; — -e.g.,  in  the  interpretation  of  relationships.  But  variations 
abound,  and  are,  as  yet,  for  the  most  part  unexplained;  probably 
often  highly  complex.  It  is  certain,  however,  that  if  these  variations  Peo^'  2r'oot 
can  be  envisaged  and  understood,  they  will  serve  as  basic  data.  (^naiis)a  nat~ 

There  seems  at  present  no  way  of  stating  exactly  the  upper  f^^d11!* 
limit  of  the  numbers  representing  these  variations  of  the  1,  2,  4  S^fcaSfc 
series  as  exemplified  in  an  organism.  It  may  in  some  organisms  latus- 
reach  twenty  figures,  and  therefore  the  discovery  and  interpretation  of  some 
of  the  highest  members  of  this  modified  geometrical  series,  as  exemplified  in 
organisms,  may  be  beyond  our  present  compass.  Nevertheless,  does  it  not 
seem  likely  that  relationships  traced  in  this  manner  may  at  .least  be  set  upon 
a  firmer  basis  than  is  the  case  when  data  of  other  sorts  are  used, — or  even 
upon  an  entirely  new  basis? 


374 


BIOLOGICAL  RELATIONSHIPS  OF  THE   1,   2,  4,   SERIES 


In  a  1,  2,  4  series,  let  PN  be  the  final  product  and  N  its  series  number, 
then  PN  =  2N-';  thus,  16  =  25"1. 

Similarly  in  a  simple  organism,  at  any  particular  instant  in  its  growth, 
let  PN  have  a  corresponding  value, — that  is  to  say,  be  the  number  of  cells 
that  either  actually  exist  or  would  have  arisen  by  the  uniform  and  continuous 
dichotomous  division  of  the  single  primal  cell.  Such  simple  and  easily 
understood  organisms  occur  among  the  lower  forms,  and  in  the  early  embry- 
onic stages  of  the  higher  forms,  but  are  rare  among  the  adult  stages  of  the 
higher  forms,  because  in  these  latter  some  cells  lag  or  cease  in  their  dichotomy, 
and  because  of  losses  of  cells  from  various  causes.  Hence,  the  number  of 
cells  actually  present  in  an  organism  at  any  particular  instant  is  likely  to  be 
PN  minus  a  certain  number  of  cells,  (X),  due  to  delay  or  failure  in  some  part 
or  parts  of  the  dichotomy,  or  to  loss.  In  this  discussion  account  is  taken  of 
all  the  cells  that  have  been  produced  during  the  growth,  whether  present 
in  the  organism  at  the  proposed  instant  or  not.  This  is  in  order  to  allow  for 
worn  out  or  wasted  cells;  these,  possibly  vanished,  cells  are  included  in  PAT 

The  general  1,  2,  4  equation  of  an  organism  thus  becomes  PN  =  2N-1  —  X, 


1st.  Jtaoe 


Ectoderm  +,• 


Fig.  3. — Diagram  of  8  generations  of  cells  produced  by  dichotomous  divisions; — as,  for 
instance,  in  a  segmenting  egg.  Three  general  characters  of  tissue  are  shown:  (1)  Sexual, 
(2)  intestinal  and  related  tissues,  (3)  ectoderm  and  related  tissues.  The  sexual  and  in- 
testinal tissues  are  shown  to  have  lagged  behind  those  of  the  ectoderm,  so  that  PN  in  this 
instance  equals  71. 

in  which  X  is  a  whole  number  and  a  function  of  one  or  more  "p's"  of  a  lower 
order,  i.e.,  of  the  1,  2,  4  character,  or  p  =  2n-1  character,  in  which,  of  course 
p  is  smaller  than  P  and  n  is  smaller  than  N.  These  smaller  (ascertainable) 
groups  are  1 ,  2,  4  groups  of  cells  due  to  the  lag  or  failure  of  "earlier"  generations 
than  N.  (See  the  loop  (X)  in  Fig.  3.) 

PN  =  2N-1  —  X  is  a  general  equation,  which,  when  X  =  0,  represents  a 
strictly  uniform  and  continuous  mathematical  dichotomy,  found  only  in  the 
lower  organisms  or  in  the  early  embryonic  stages  of  the  higher  ones. 

The  various  "p's"  from  PN  down  to  P  =  1,  (the  primal  number)  become, 
therefore,  historical  insignia,  indicating  particular  generations  of  cells,  and 
may  be  made  the  basis  of  a  definite  and  fundamental  mathematico-biological 
nomenclature  applicable  to  the  generations  of  cells  in  an  organism,  and  hence 
to  the  organism  itself.  Applications  of  the  equation  are  endless. 


NEMIC  SPERMATOGENESIS 

With  a  suggested  discussion  of  simple  organisms,— Litobionts 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XVI 

BY  N.  A.  COBB 

Definitions.  Spermatidium:  one  of  a  plurality  of  cells  derived 
from  a  spermatid  by  subdivision;  a  secondary,  tertiary,  or  quaternary, 
etc.,  spermatid.  Spermule:  an  individual 
spermatidium  which,  after  growth  and 
transformation,  is  capable  of  activating 
or  fertilizing  an  egg, — being  not  a  meta- 
morphosed spermatid,  but  a  descendant 
of  a  spermatid,  one  or  more  cell-genera- 
tions removed. 

The  definitions  will  be  better  under- 
stood by  at  once  consulting  the  illustra- 
tions, especially  spmtd  and  spml  Figs.  2 
and  12. 

Spermatogenesis.  At  the  blind  end  of 
the  single  testis  of  the  nema,  Spirina  para- 
sitifera  (Bastian  '65)  Filipjev  (Figs.  1 
and  2) , — a  free  living  marine  species,  com- 
mon an  inch  or  two  deep  in  sand  and 
among  small  stones  between  the  tide 
marks  of  protected  coasts  on  both  sides 
of  the  North  Atlantic  through  a  wide 
range  of  latitude, — the  primordial  gonic 
elements  give  rise  by  14-chromosome 
mitotic  division  to  numerous  twin  cells 
(Figs.  2,  14),  which  arrange  themselves 
tandem  in  the  testis  (Fig.  3)  where  each 


dgng. 


Fig.  1. — Lateral  view  of  the 
head  of  Spirina  parasitifera. 
The  amphidial  nerve,  nrv  amph, 
expands  into  a  sensilla,  then 
again  into  a  10-12  celled  ganglion 
(seen  through  the  lateral  chord, 
chrd.  lat.)  joining  the  nerve-ring, 
cor  nrv. 


Waverly  Press,  Baltimore,  Md.,  June  9,  1928. 
material  alterations. 


From  Jour.  Wash.  Acad.  Sc.,  Jan. 


Repaged  without 


376 


ANATOMY   OF   SPIRINA 


Method.  Mount  live  nema  in 
sea  water  on  large  cover-glass; 
cover  with  round  one.  Draw 
off  excess  water  till  nema  can 
barely  move.  Seal  with  hot 
wax.  Use  high  immersion  ob- 
jective as  condenser,  its  mate 
as  objective.  Slight  move- 
ment of  nema  aids  deciphering. 
Stain  ruptured  nemas  for  fuller 
examination. 


94.8 


»2JO«« 


dU''M 


.  .isc&zd  cs 


X250 


Fig.  2.— The  male  of  S.  parasitifera  drawn  from  life.  The  tinting  of  drawing  modi- 
fied in  accordance  with  study  of  stained  specimens.  Nearly  all  details  shown  were  seen 
in  the  living  specimen.  The  front  view  of  head,  however,  is  from  a  decapitated  speci- 
men. In  life  the  chromosomes  have  not  been  seen  definitely  enough  to  admit  of  accurate 
counting.  Most  of  the  subsequent  camera  lucida  drawings  were  obtained  from  fixed 
and  stained  material.  In  nearly  all  cases  the  fixing  and  staining  were  done  simulta- 
neously by  means  of  acetic  acid  methyl  green.  Just  to  the  right  are  placed,  in  the 
form  of  the  decimal  formula,  the  average  measurements  of  specimens  used.  Material 
collected  at  Woods  Hole,  Mass.,  U.  S.  A. 

The  self-explanatory  abbreviations  are  the  same  throughout  the  various  figures, 
and  are  of  necessary  Latin  anatomical  terms;  thus,  chrd  lat,  chorda  lateralis,  lateral 
chord;  qrt,  quartet  of  spermatids;  chrtd,  chromatoids;  spmtd,  spermatid;  alv  ncl,  alveoli 
of  nuclear  space;  micrsm,  microsomes,  of  spermatid;  14,  a  14-chromosome  spermato- 
gonial  mitosis;  mil,  mitotic  figure;  grn,  a  cell  of  primary  spermatidian  tissue  containing 
four  granules;  grn  16,  cell  o?  spermatidian  tissue  containing  sixteen  granules;  locus 
ncl  alv,  locus  of  the  diminishing  alveolated  nuclear  space;  spmtd  polyncl,  polynucleate 
spermatid  in  process  of  becoming  a  64-celled  tissue;  textus  spmtdi,  spermatidian  tissue. 


REDUCTION   DIVISION  377 

cell,  growing,  forms  a  primary  spermatocyte.  At  the  end  of  the 
growth  period  the  primary  spermatocytes,  one  after  another,  divide 
transversely,  i.e.,  at  right  angles  to  the  nema's  body  axis,  and  then, 
sometimes  almost  simultaneously,  longitudinally,  to  produce  four  simi- 
lar, juxtaposed  spermatids  (Fig.  2,  qrt),  each  soon  packed  with  several 
thousand  very  slightly  elongate  microsomes,  nearly  all  of  which  are 
located  outside  the  large  central,  faintly  alveolated,  diminishing  nuclear 
space.  (Fig.  2,  micrsm  and  alv  ncl;  and  Fig.  14.) 

The  microsomes  seem  to  arise  toward  the  center  of  the  spermatid 
and  migrate  outward  till  the  entire  cell  is  colonized  by  them.  Seen 
toward  the  center  of  the  spermatid  they  usually  have  their  long 
axes  arranged  radially,  as  if  moving  outward,  end  on.  Some  8- 
10,000  uniform  microsomes  come  thus  into  existence  in  each  sperma- 
tid. The  arrangement  of  these  around  64  centers  is  the  first  indica- 
tion of  the  formation  of  the  first  generation  of  64  spermatidia.  In 
the  living  spermatids  the  microsomes  are  the  only  objects  seen 
visibly  connected  with  such  a  division  of  the  cell  contents  as  is 
necessarily  postulated  to  account  for  the  phenomena  of  heredity. 


l 


Fig.  3  Fig.  4 

Fig.  3. — View  near  blind  end  of  testis  of  S.  parasitifera,  showing  pairs  of  cells  result- 
ing from  division  of  primordial  nuclei.  This  testis  had  broken  open  and  become  par- 
tially evacuated  so  that  these  pairs  of  cells  in  tandem  could  readily  be  distinguished  as 
such.  Normally  these  nuclei  are  so  packed  that  the  mass  effect  obscures  the  fact 
that  they  are  twins. 

Fig.  4.— Second  stage  of  reduction  division  of  a  spermatocyte  of  S.  parasitifera, 
which  will  result  in  4  similar  juxtaposed  spermatids,  as  at  qrt,  Fig.  2,  each  having  7 
chromosomes.  The  compound  chromosomes  present  considerable  individuality. 
Between  the  2  double  groups  of  chromosomes  is  seen  portion  of  the  new  cell  wall. 
X  1200. 

In  the  first  of  these  two  divisions  the  chromosome  number  is  re- 
duced to  seven.  Probably  the  smallest  one  of  the  seven  chromosomes 
of  the  secondary  spermatocytes  differs  slightly  in  relative  size  in  the 
two  cells.  Thus  far  the  spermatogenesis  presents  nothing  very  new 
or  striking,  but  the  amount  of  growth,— from  3  to  60  microns  (tst, 
Fig.  2),- — is  worthy  of  note,  and,  connected  with  reduction,  there  is 


378  SYNAPSIS;  SPERMATIDIAN  GRANULES 

a  more  or  less  orderly  (e.g.,  more  or  less  definitely  oriented)  extrusion 
from  the  spermatids  of  structureless  looking  chromatoid  substance, 
(chrtd  Fig.  2  and  Fig.  14),  barely  possibly  by  a  very  "degenerate" 
mitosis;  these  chromatoid  masses  are  soon  absorbed. 

"Normally,"  the  four  cells  just  described  would  develop  into  four 
sperms,  but  here  the  spermatogenesis  proceeds  as  follows:  Moving 
along  the  testis  with  soldier-like  precision,  the  two  caudad  members 

.nd 


H200 
Fig.  5 

Fig.  5.— Nucleus  of  full  grown  spermatocyte  seen  in  synapsis.  The  nuclear  mem- 
brane is  still  intact  and  the  spherical  nucleolus  is  still  visible.  The  chromosomes  are 
in  seven  pairs.  It  was  possible  to  resolve  the  chromosomes  into  numerous  components, 
suggesting  a  possible  explanation  of  the  difference  in  chromosome  counts  in  certain 
nemas,  e.g.,  in  Ascaris;  i.e.,  differences  between  counts  at  this  stage  and  counts  in  later 
somatic  divisions;  for,  should  such  loosely  organized  chromosomes  later  break  apart, 
the  count  would  be  much  increased. 

Fig.  6. — A  single  spermatidium  of  first  generation  with  its  nucleus  and  sixteen 
granules.  From  life.  In  this  case  the  cell  wall  is  shown. 

Fig.  7. — Above,  camera  lucida  drawing  of  nuclei  and  granules  in  spermatidia  of 
S.  parasitifera  at  the  point  grn  (4),  Fig.  2.  Below  a  diagram  of  four  spermatidia.  The 
diagram  is  derived  from  drawing  above,  and  shows  more  clearly  the  numerical  rela- 
tionships of  nuclei  and  granules.  The  boundaries  of  the  spermatidia  are  almost  in- 
visible and  are  not  shown.  The  granules  are  shown  black,  white  or,  when  seen  through 
the  nucleus,  gray.  The  larger  ellipsoidal  objects  are  nuclei.  In  the  drawing,  at  top 
and  on  the  hither  side,  a  nucleus  with  its  accompanying  four  granules,  the  nucleus 
being  this  side  of  granules.  In  the  drawing,  on  the  farther  side,  again  at  top,  a  sperma- 
tidium three  of  whose  granules  have  already  given  rise  to  four  smaller  granules  each. 
In  the  drawing  and  below,  a  spermatidium  none  of  whose  four  granules  have  divided, 
one  of  them  shown  behind  the  nucleus,  grn  (16)  shows  a  spermatidium  with  a  nucleus 
and  16  granules.  The  lower  figure  is  only  somewhat  schematised.  Very  rarely  are 
spermatidian  cells  so  systematically  arranged  as  to  disclose  so  clearly  the  relationships 
of  granules  and  nuclei.  In  this  diagrammatic  lower  figure  the  far  spermatidium  is 
shown  in  an  intermediate  state.  Illustration  derived  from  material  stained  with 
methyl  green. 

of  the  quartet  form  a  tandem,  followed  by  the  other  two,  also  in 
tandem;  i.e.,  the  quartet  falls  into  single  file.  These  spermatids  in 
file  grow,  and  one  after  another  divide  internally  without  evidence 
of  mitosis  into  64  uninucleate  elements  which  proceed  to  surround 
themselves  with  walls  and  form  a  tissue  of  64  cells.  (See  lowest  part 
of  Fig.  2.)  As  this  tissue  leaves  the  testis  and  enters  the  duct  it 


ENDOGENOUS   DIVISION   OF   GRANULES 


379 


elongates  (2-4  nuclei  abreast),  and  each  of  its  64  cells  in  turn,  following 
on  the  disappearance  of  the  microsomes,  acquires  four  equal,  refrac- 
tive, spherical  granules  (4  microns  in  diameter),  and  the  tissues  thus 
take  on  a  granulated  appearance,— the  nuclei  and  cell-walls  being 
almost  completely  hidden  by  the  closely  packed  granules.  By  the 
time  the  cephalad  part  of  each  tissue  enters  the  duct  the  caudad  part 
has  undergone  a  further  change,  in  that  the  four  granules,  each  dividing 
endogenously  into  four  similar  but  smaller  spherical  granules,  popu- 
late each  cell  with  16  granules  (grn  4  and  grn  16,  Fig.  2). 

This  very  interesting  behavior  of  the  granules   (Figs.  7  and  9) 
more  than  suggests  a  different  order  of  mechanism  from  that  typical 


Fig.  11 


:1200' 


Fig.  8.— Reduction  division.  Sublimate-acid  carmine  toto  preparation.  The 
smallest  chromosome  differed  somewhat  in  size  in  the  two  sets.  Fixation  less  delicate 
than  with  acid  methyl  green. 

Fig.  9.— Two  granules  from  the  spermatidia  of  S.  parasitifera;—one  showing  4 
smaller  granules  formed  endogenously,  the  other  8.  The  right  hand  granule  is  from 
near  grn  4,  Fig.  2.  The  left  hand  granule,  taken  from  farther  back  in  the  testis,  where 
microscopic  details  are  so  fine  that  exact  relationship  of  granules  and  their  descendants 
has  not  as  yet  been  fully  deciphered. 

Fig.  10.— Spermatidia  each  containing  sixteen  refractive  spherical  granules.  From 
life.  The  cell  walls  and  nuclei  of  this  tissue  are  nearly  invisible  in  life. 

Fig.  11. — Nuclear  spindles  in  later  mitoses  of  spermatidia  taking  place  in  vas 
deferens.  Polar  views  of  spindles  show  7  chromosomes;  see  small  figures  to  right, 
from  another  part  of  the  same  specimen. 

of  cell  division,  but  since  irritability,  ingestion,  transportation,  trans- 
formation and  so  forth,  all  seem  involved,  it  appears  necessary  to 
base  the  concept  on  what  is  known  of  cell  physiology  and  mechanics; 
the  changes,  however,  are  carried  out  on  a  smaller  scale  and  doubt- 
less with  a  more  limited  variety  of  molecules  forming  a  different 
kind  of  plasm — litoplasm.  In  short,  the  facts  indicate  a  distinctly 
lower  order  of  "organism."  Many  of  what  now  are  often  called 
lower  organisms  might  better  be  regarded  simply  as  less  multiplicate. 
Thus  certain  ciliates  are  smaller  and  less  multiplicate,  rather  than 
"lower,"  as  compared  with  nemas  for  instance.  This  matter  is 


380 


FERTILIZATION 


ndooajt 


.inn  of 


.rag 


^— H   •  fl\ -or    briefly  discussed  on  a  later  page, — under  the 
Y  heading,   Size   and  Number  as  related  to  Or- 

ganisms. 

As  the  tissue  proceeds  along  the  duct,  the 
cells  containing  16  granules  undergo  a  further 
diminution  in  the  size  of  their  granules,  and  a 
change  in  the  number  and  nature  of  the  gran- 
ules, so  that  the  cells  become  more  transparent; 
at  the  same  time  the  nuclei  divide  mitotically, 
Mspmtd  (7  chromosomes),  giving  rise  to  a  tissue  of  128 
cells.  The  evidence  that  this  increase  is  by 
rf  mitosis  is  as  follows:  1.  At  the  part  of  the  duct 
where  this  change  is  taking  place  (Fig.  11)  the 
sizes,  form  and  position  (in  pairs)  of  the  new 
*  nuclei  are  what  would  be  expected  from  mitotic 
division.  2.  The  new  smaller  nuclei, — pos- 
terior to  the  larger,  as  yet  undivided,  nuclei, — 
stain  more  strongly.  3.  Occasionally  7-element 
spindles  can  be  seen.  4.  No  trace  has  been 
seen  of  any  other  sort  of  division. 

Two  or  more  such  tissues  as  that  described  fill 
the  duct  of  the  male  nema,  the  number  of  tis- 
sues varying  with  the  age  of  the  nema  and  with 
the  copulatory  history.  The  tissues  seem  to  be 
of  two  styles,  and,  if  so,  perhaps  correspond  to 
the  two  styles  of  chromosomes  in  the  second- 
ary spermatocytes  (textus  spmtdi,  Fig.  2). 

Fertilisation  and  Syngamy.  The  two  sexes 
of  S.  parasitifera  seem  about  equally  common. 
During  copulation  the  male  passes  the  sper- 
matidian tissues  on  intact  to  the  female,  and 
afterward  they  may  be  seen  in  the  uteri, 

nd OOcyt  Fig.  12.— Carefully  proportioned  free-hand  sketch  of 
gonads  of  female  S.  parasitifera  after  impregnation.  The 
two  uteri,  outstretched  in  opposite  directions,  are  filled 
with  spermatidian  tissue.  The  young  ovaries  are  just  be- 
.Ja  Of  ginning  to  function  and  the  ova  next  the  flexures,  flex  ov, 
are  about  to  enter  the  uterus.  The  spermatidia  adjacent  to 
the  ova  about  to  enter  the  uteri  have  metamorphosed  into 
xg~  spermules,  spml,  and  have  taken  on  the  form  characteris- 
tic of  nemic  sperms  as  hitherto  described.  In  this  case 
two  other  cells  of  the  spermatidian  tissue  nearer  the  vulva  have  also  begun  to  meta- 
morphose, trm,  blind  end  of  ovary;  flex  ov,  flexure  of  ovary;  txt  spmtd,  spermatidian 
tissue;  gl  vag,  vaginal  gland,  for  which  see  also  Fig.  16. 


.glrag 


Mspatd 


•trm  or 


spoil 


SYN  APSIS  381 

often  jumbled,   sometimes   extended   along   the  length  of  the  two 
uteri. 

Fertilization  is  preceded  by  increase  in  size  of  that  cell  of  the 
speraiatidian  tissue  adjacent  to  the  ovum  next  to  be  fertilized  and 
its  transformation  into  a  cell,  spermule,  having  the  form,  and  dis- 
charging the  functions,  of  a  nemic  sperm  as  hitherto  understood;  —  • 
a  transformation  involving  a  growth  of  about  50  per  cent  in  diameter 
together  with  a  greater  growth  longitudinally,  and  &  marked  change 
in  the  granulation  of  the  cytoplasm  (spml,  Fig.  12).  These  trans- 
formed cells,  detached  one  by  one,  fertilize  the  eggs  in  what  seems  a 
normal  manner.  The  polocytes  seem  normal.  The  female  gamete 
has  seven  chromosomes  (Fig.  13). 


The    spermatidian    tissues  -tissues  0J1 


, 

whose   history   seems    to   justify   US   in    parasitifera,  in  synap- 
j  .          ,  i  i  sis.     Above,  cf  zygote. 

regarding  them  as  spermatophores,  —  Below,   9  nucleus  in 
may  be  removed  from  either  the  male  synapsis;  one  set   of 

chromosomes      shown 

or  the  female  nema  and  then  separately  behind  the  other  and 
stained  and  examined,   and  this  has 


been  repeatedly  done;  hi  which  case  scured  by  their  posi-; 

the  details  of  their  structure  can  of 

course  be  seen  with  greater  ease  and    || 

distinctness  than  is  the  case  with  such    |§; 

living  preparations   as   are  shown  in    |;| 

figures   1   and   12.     The  enumeration    %| 

of  the  elements  of  the  128-cell  stage    ;  <  V 

of  the  spermatidian  tissue  was  found  ^~~^<^_^~~~^^ 

possible  in  this  way,  as  well  as  in  balsam  specimens  fixed  in  corro- 

sive sublimate  and  stained  in  Mayer's  acid  carmine. 

This  method  of  spermatogenesis  is  normal  to  nemas.  A  large 
number  of  species  belonging  to  numerous  and  varied  genera  are 
known  to  the  writer  in  which  the  general  appearances  in  the  gonad  of 
the  male  so  closely  resemble  those  of  Spirina  parasitifera  as  to  leave 
him  no  doubt  that  the  details  of  their  spermatogenesis  will  show  the 
features  here  described,  or  something  similar.  The  formation  of  the 
spermatidian  tissue  is  not  an  essential  feature;  in  others  of  the  above 
species  the  spermatidia  may  remain  separate. 

Current  postulates  must  be  modified  in  order  to  account  for  heredi- 
tary transmission  in  this  and  similar  animal  species.  The  factors 
usually  believed  to  reside  wholly,  or  in  part,  in  the  chromosomes 
must  here,  in  order  to  accord  with  the  usual  theories  of  heredity, 


382  DIAGRAM   OF   SPERMATOGENESIS 

Twin  5pmotogonia 


:Xl25 


Fig.  16 


Fig.  17 


ad.. 


Fig.  14 


Fig. 15 


Fig.  14.— Boverian  diagram  of  spermatogenesis  of  Spirina.  Spermatids  are  formed 
in  the  "conventional"  way.— four  from  a  spermatocyte.  Instead  of  metamorphosing 
into  ciliated  spermatozoa,  the  spermatids  undergo  further  changes  and  divisions,  which 
give  rise  to  a  spermatidian  tissue  of  64  cells  from  each  spermatid.  These  by  mitotic 
division  produce  128-celled  tissues.  One  by  one  the  spermatidia,  when  transferred  to 
the  uteri  of  a  female,  grow  into  spermules,  capable  of  activating  an  egg  and  initiating 
normal  development.  Whether  every  one  of  the  128  metamorphose  in  this  way  is  as 
yet  undetermined. 

Fig.  15.— Two  views  of  one  of  the  lateral  glands  of  5.  parasitifera.  At  the  left  only 
the  pore  and  distal  portions  of  gland  are  shown.  The  gland  is  uninucleate  and  consists 
mainly  of  spherical  granules.  Spent  glands  contain  fewer  granules  than  that  shown. 

Fig.  16.— Ventral  view  of  vulva  and  vaginal  glands  of  5.  parasitifera.  See  also 
Fig.  12. 

Fig.  17.— Lateral  view  of  one  of  the  lateral  glands  of  S.  parasitifera.  The  gland 
in  a  different  state,  or  stage  of  development,  from  that  shown  in  Fig.  4. 


LATERAL  PORES  AND  GLANDS  383 

be  "divisible"  in  the  spermatid  into  numerous  parts  such  that  when 
they  appear  in  the  spermule  they  are  capable  of  bringing  about 
"normal"  syngamy. 

It  will  be  interesting  to  discover  how  factors  or  genes,  concepts 
essential  to  clear  thinking  on  the  subject  of  heredity,  can  be  imagined 
to  "carry  on"  through  the  mazes  of  the  division  that,  extending 
throughout  the  spermatid,  gives  rise  without  mitosis  to  64  apparently 
equivalent  elements  in  the  spermatidian  tissue  (see  spmtd  polyncl, 
Fig.  2).  The  spermatidian  tissues  (aggregates  of  haploid  cells,— 
gametophores — Fig.  12)  seem  more  clearly  reminiscent  of  the  alter- 
nation of  generations  in  plants  than  any  animal  structure  hitherto- 
made  known. 

Subjoined  is  an  alteration  of  the  Boverian  diagram  illustrating 
the  spermatogenesis  here  described.  It  will  be  seen  that  in  this 
Boverian  diagram  (Fig.  14)  the  proportions  of  the  camera  lucida 
drawing  (Fig.  2)  are  to  a  large  extent  adhered  to.  The  microsomes 
and  the  alveolated  nuclear  spaces  are  shown  with  no  very  great 
departure  from  nature.  The  number  and  size  of  the  microsomes  is 
approximately  correct  and  the  new  arrangement  of  the  microsomes 
around  64  centers  as  shown  in  the  diagram  is  not  violently  schematized. 
The  same  is  true  of  the  size,  color  and  disposition  of  the  chromatoid 
bodies.  For  simplicity  the  spermatidian  tissues  are  reduced  in  the 
diagram  to  masses  of  64  and  128  nuclei  respectively. 

The  features  accompanying  and  following  the  oocytic  synapsis  seem 
at  least  a  gesture  toward  the  path  followed  in  the  spermatogenesis, 
but  they  have  not  yet  been  carefully  studied. 

Occasion  for  staining  the  gonads  of  Spirina  parasitifera  offered  an 
opportunity  for  a  more  careful  study  of  the  unicellular  glands  of 
this  species  that  "empty"  through  minute  pores  in  the  cuticle  of  most 
regions  of  the  body,  but  particularly  along  the  lateral  fields.  Uni- 
cellular structures  of  this  character  are  known  to  be  widespread 
among  nemas,  having  been  recorded  for  a  great  variety  of  free-living 
genera  and  a  few  parasitic  genera.  It  is  not  known  whether  the 
various  unicellular  organs  of  this  character  hitherto  recorded  are 
homologous  or  whether  they  are  connected  with  a  variety  of  func- 
tions. The  fact  that  they  are  well  developed  on  aquatic  forms  that 
experiment  proved  to  be  in  urgent  need  of  oxygen  has  led  the«  writer 
to  suggest  the  possibility  that  these  "glands"  or  some  of  them,  may 
be  connected  in  some  way  with  respiration.  This  would  seem  in 
accord  with  the  failure  hitherto  to  observe  any  such  organs  in  the 


384  SIZE   AND   NUMBER   AS    RELATED   TO    ORGANISMS 

vast  majority  of  the  parasitic  species,— whose  "respiration"  it  would 
seem  natural  to  explain  in  other  ways. 

In  Spirina  parasitifera  these  organs  are  very  small,  and  it  therefore 
seems  not  unlikely  that  the  present  methods,  when  applied  to  more 
suitable  material,  may  give  results  much  more  detailed  and  intelligible. 
The  structure  of  one  of  these  glands  of  S.  parasitifera,  so  far  as  deter- 
mined, is  shown  in  Figs.  15  and  16.  The  great  difference  in  the  size 
of  the  organs  in  the  two  cases,  as  well  as  the  difference  in  structure 
and  space  relationships,  suggests  the  probability  that  the  shape  of 
the  organ  changes  materially,  perhaps  rapidly,  under  various  condi- 
tions. To  this  surmise  it  may  be  added  that  the  method  of  collect- 
ing the  spirinas,  and  the  varying  length  of  time  between  their  exis- 
tence under  natural  conditions  and  the  time  of  examination,  would 
result  in  a  very  material  alteration  in  the  environment;  and  it  is 
believed  that  the  longer  this  time  became  the  less  free  oxygen  would 
exist  in  the  sea  water  in  which  the  specimens  were  kept.  This  length 
of  time  varied  widely. 

SIZE   AND   NUMBER  AS   RELATED   TO   ORGANISMS 

The  interesting  behavior  of  the  spermatidian  granules  as  described 
on  pages  38  to  41  has  suggested  the  following  sketchy  discussion  of 
the  relationship  of  organisms  to  size  and  number. 

Why  not  vertebrates  a  mile  long  and  a  thousand  feet  high?  Why 
not  vertebrates  only  a  quarter  of  an  inch  long?  The  known  facts 
clearly  indicate  limits  in  both  directions. 

Among  the  reasons  for  the  existence  of  the  upper  limit  are,  circula- 
tion difficulties  due  to  friction  in  the  blood  vessels;  accumulation  of 
an  excess  of  excreta  in  the  blood  during  the  long  journey  to  the  dis- 
tant extremities  and  back;  the  difficulty  of  maintaining  the  requisite 
temperature  at  the  extremities;  limits  set  by  the  strength  of  ma- 
terials,— bone  could  not  be  strong  enough  or  muscles  efficient  enough 
properly  to  support  and  move  so  large  an  organism;  food  supply 
difficulties;  space  limitations  connected  with  protecting  such  an 
organism  from  the  elements,  etc.,  etc. 

Reasons  for  the  non-existence  of  exceedingly  small  vertebrates 
also  come  readily  to  mind.  The  complicated  vertebrate  mechanism 
would  be  in  the  way  in  an  organism  of  such  small  size.  Why  an 
elaborate  pumping  system  to  pump  blood  for  a  distance  through  which 
it  might  diffuse  without  such  a  system?  So  with  "centralized" 
respiration.  An  internal  skeleton  plus  the  necessary  protective 


SIZE   AND   NUMBER   AS   RELATED   TO   ORGANISMS  385 

cuticle  become  incompatible  in  this  range  of  sizes.  The  competition 
of  such  imaginary  small  vertebrates  with  other  organisms,  say  insects, 
of  simpler  structure  better  adapted  to  such  small  sizes  would  be  a 
hopeless  struggle. 

Why  not  insects  as  large  as  moles  or  as  small  as  microbes?  Here 
again  the  mechanical  relations  of  the  organism  to  the  menstrua 
furnish  numerous  reasons  for  the  known  size  limits. 

Generalizing,  why  not  multicellular  organisms  beyond  certain 
maximum  and  minimum  limits?  A  little  thought  shows  that  limits 
are  set  by  the  relationships  of  particular  mechanisms  to  the  sizes  and 
distances  involved;  and  as  size,  in  such  cases,  is  a  function  of  the 
number  of  cooperating  cells,  the  limits  are  set  in  numerical  terms. 
This  becomes  clearer  when  we  consider  our  ability  to  represent  a 
cellular  organism  by  a  strictly  numerical  expression,  the  bioequation,2 
and  all  the  more  certainly  true  when,  continuing  the  same  line  of 
thought,  we  consider  the  size  limits  of  cells. 

Why  do  we  not  have  cells  a  meter  long;  and  why  not  typical  cells 
below  the  limits  of  a  micron  or  two?  Again,  among  other  reasons, 
in  this  range  of  still  smaller  sizes  the  mechanism  of  the  typical  cell 
becomes  so  complex  as  to  "be  in  its  own  way"  when  the  distances 
involved  become  sufficiently  small  and  the  number  of  properties  to  be 
transmitted  sufficiently  few,  as  will  be  indicated  in  a  moment. 

Size  limits  in  these  various  cases  are  set  by  a  fundamental  neces- 
sity, having  its  "final"  source  in  the  size  of  the  electronic  combinations. 

Particular  attention  is  called  to  the  fact  that,  usually,  the  size 
limits  of  "adjacent"  higher  and  lower  groups  of  organisms  reciprocally 
overlap  (e.g.  Vertebrates  and  Insects);  as  well  as  to  the  fact  that 
individuals  of  certain  species  of  unicellular  organisms  are  larger 
than  some  of  the  multicellulars;  or,  to  emphasize  by  reversing,  many 
multicellulars  are  smaller  than  some  of  the  larger  unicellulars.  There 
is  a  distinct  lapping  of  the  size  limits  of  one  on  to  the  size  limits  of 
the  other. 

Organisms  of  greater  size;  "social  organisms."— Developing  a  more 
complex  nervous  system,  the  higher  organisms  have  evolved  "mental 
pictures"  of  distant  and  invisible  things  and  events,  and  have  in- 
vented means  for  transmitting  through  various  media  signs  that 
represent  these  mental  pictures.  Along  this  path  the  social  organisms 
evolved.  When  we  speak  of  a  social  organism  it  is  usually  assumed 

"Biological  Relationships  of  the  Mathematical  Series  1,  2,  4,  etc."  Contributions 
to  a  Science  of  Nematology  XV. 


386  INDIVIDUALITY    OF   CELLS 

that  we  are  using  analogy,  but  an  interesting  formulation  might  be 
made  out  for  homology.  Are  not  the  interactions  between  rela- 
tively widely  separated  intellectual  individuals,  existing  in  the  sea 
of  air  surrounding  the  earth,  in  many  ways  actually  homologous  with 
the  passage  of  stimuli,  etc.,  through  more  viscous  fluid  media  between 
cells?  As,  for  instance,  when  two  small  organisms  live  in  symbiosis; 
or,  where  cells  exist  together  as  they  do  in  blood;  or,  between  cells 
even  more  intimately  organized. 

The  concept  of  organisms  of  this  higher  or  social  grade  suggests 
the  possibility  of  there  being  also  lowrer  orders  of  organisms  at  the 
other  end  of  the  accepted  series.  This  idea  is  not  new,  for  their 
existence  was  specifically  asserted  by  acute  observers  and  adventurous 
thinkers  in  the  plainest  of  language  at  least  half  a  century  ago;  but 
at  that  time  the  supporting  evidence  was  so  meagre  that  the  idea 
did  not  rise  to  the  dignity  of  an  acceptable  working  hypothesis. 
Now  it  is  quite  different.  Today  what  we  know  about  certain  small 
living  elements,  both  inside  and  outside  of  cells,  compels  such  a 
working  hypothesis/ — if  mayhap  we  are  not  already  beyond  the 
hypothetical  stage. 

Here  again,  size  seems  a  prime  determining  element.  When  a 
cell  (really  a  relatively  complex  and  large  organism)  transmits  its 
exceedingly  numerous  properties  to  its  "descendants,"  nothing  short 
of  an  elaborate  mobilization  and  census  is  adequate  to  the  coming 
transmigration.  Hence  follow  mitosis  and  its  complications. 

We  are  perhaps  prone  to  forget  that  every  cell  has,  in  a  great  degree, 
to  care  for  itself;  and  so  must  have  many  of  the  multitudinous  proper- 
ties characteristic  of  the  groups  of  cells  constituting  higher  organisms. 
It  must  nourish  itself.  "You  can  take  the  horse  to  food  (or  vice 
versa),  but  you  cannot  make  him  eat; — he  must  do  that  himself," 
seems  to  summarize  the  situation.  If  the  cell  assimilates  ("eats"), 
and  is  to  continue,  then  it  must  have  mechanism  adequate  to  select, 
transport,  digest,  excrete,  etc.,  and  at  least  to  take  some  part  in 
reproducing  itself.  All  this  complexity  is  because  of  the  number  of 
its  characteristics,  and  because  of  the  size,  i.e.,  the  distances  involved. 
But  what  if  all  these  be  a  hundredfold  or  more  reduced,  and  the 
system  be  at  the  same  time  "isolated"  or  individualized?  Plainly, 
the  requirements  would  call  for  a  simpler  mechanism;  cell-mechanism 
would  be  so  complicated  as  to  be  in  the  way.  Under  such  conditions 
simpler  organisms,  organisms  simpler  than  cells,  seem  a  logical 
necessity. 


LITOBIONTS  387 

Litobionts.—l  have  ventured  to  suggest  a  general  or  inclusive 
name,  Litobionts,  for  the  organisms  which  my  observations  lead  me 
to  believe  to  exist,  these  very  organisms  of  lower  grade; — (Xtros, 
simple),  simple-organisms.  The  Litobionts  have  distinctive  char- 
acters, such  as  small  size,  and  simplicity  of  composition,  but  neverthe- 
less, live,  assimilate,  grow,  multiply; — not  only  segmenting  somewhat 
after  the  manner  of  some  higher,  more  or  less  filamentous  organisms, 
but  multiplying  by  endogenous  division,  this  latter  being  one  of  the 
present  observations,  the  endogenous  process  being  exemplified  in 
the  "granules"  of  the  spermatidia  of  Spirina.  (See  p.  41.) 

Yet  it  is  possible  to  over-emphasize  the  smallness  of  Litobionts. 
It  seems  likely  that  we  have  been  looking  at  Litobionts  a  long  time, — 
Litobionts  of  the  larger  size, — without  recognizing  their  nature,  just 
as  observers  previous  to  the  tune  of  Schleiden  and  Schwann  had 
been  looking  at  cells  without  recognizing  their  nature. 

Just  as  the  multicellular  and  unicellular  organisms  overlap  each 
other  in  the  matter  of  size,  so  the  unicellular  organisms  (having  the 
characteristic  properties  of  cells  as  now  defined)  overlap  the  Lito- 
bionts. There  are  unicellular  organisms  smaller  than  some  Lito- 
bionts. Or,  in  reverse,  some  Litobionts  larger  than  some  unicellular 
organisms. 

That  the  Litobionts  are  much  simpler  than  cells,  is  indicated  by  a 
number  of  considerations.  Their  effects  on  light  indicate  that  in 
the  main,  they  are  composed  of  a  smaller  number  of  kinds  of  molecules 
of  a  more  orderly  arrangement, — what  may  perhaps  be  thought  of 
as  forming  a  simpler  plasm,  Litoplasm.  The  fact  that  some  of  them 
are  soluble  in  certain  chemical  reagents  (e.g.,  acetic  acid),  is  another 
indication  of  relative  simplicity.  In  a  word,  we  must  conceive  of 
the  Litobionts  as  made  up  of  a  smaller  number  of  kinds  of  simpler 
molecules  manipulated  through  very  much  smaller  distances,  and 
therefore  necessarily  (a  matter  of  "economy,"  'least  resistance")  by 
simpler  mechanism.  It  is  quite  conceivable  that  some  Litobionts 
may  be  smaller  than  some  of  the  largest  molecules.  Not  needing 
these  large  and  complex  molecules,  the  mass  of  the  Litobiont  may 
even  be  smaller  than  that  of  some  such  molecules. 

The  duality  characteristic  of  all  matter  must  lead,  however,  to  an 
arrangement  of  the  parts  in  Litobionts  such  that  we  can  only  think 
of  them  at  present  largely  in  terms  of  what  we  know  of  cell  physiology 
and  mechanics;  simply  because  knowledge  progresses  exclusively 
through  the  known  to  the  unknown.  Our  knowledge  of  cells  must  be 
one  of  the  main  sources  of  our  Litobiont  concepts. 


THE  SCREW  NEMAS 

(Ascarophis  van  Beneden,  1871) 

PARASITES  OF  CODFISH,  HADDOCK  AND  OTHER  FISHES 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XVII 

BY  N.  A.  COBB 

The  screw-nemas,  as  it  is  here  proposed  to  call  them,  have  yet  to  be 
adequately  studied.  Not  very  much  has  been  added  to  van  Beneden's 

original  description.  Almost  nothing 
is  known  about  their  life  history  and 
habits.  However,  the  present  commun- 
ication adds  considerably  to  our  knowl- 
edge of  their  morphology.  The  sug- 
gested explanation  of  the  remarkable 
screw  form,  and  its  probable  mode  of 
evolution,  present  the  nemic  cuticle  in 
a  new  role.  (See  Figs.  5,  6,  and  7.) 

Considering  the  number  of  screw- 
nemas  thus  far  seen,  it  is  remarkable 
that  no  males  have  been  discovered. 
Nicoll  records  screw-nemas  as  "ex- 
tremely numerous"  in  haddock.  Van 
Beneden  found  them  originally  in  the 
codfish;  Nicoll,  in  the  codfish  and  had- 
dock, and  in  the  fishes  Hippoglossus 
vulgaris  and  Coins  bubalis;  MacCallum 
now  finds  a  species  in  the  stingray. 

Nemas  so  widespread  and  numerous 
probably  have  economic  significance. 
This  probability  can  not  be  dismissed 
by  citing  the  absence  of  definite  evi- 
dence to  the  contrary,  for,  at  rather 
frequent  intervals  nowadays,  nematolo- 
gists  are  showing  that  nemas  long 
known  and  lightly  regarded,  are  not 
only  of  some  importance  in  their  rela- 
tionship to  mankind  but  sometimes  of 
great  importance;  and  the  multitudi- 


X400 


Fig.  1.— Head  and  tail  end  of 
Ascarophis  helix  n.  sp.  Above,  to 
the  right,  front  view  of  the  lip 
region.  The  head  end  is  nearly  a 
ventral  view,  but  slightly  oblique. 
The  tail  end  is  a  dorsal  view,  and 
the  anus,  being  on  the  far  side,  is 
but  indistinctly  shown. 


nous  ways  in  which  this  comes  about  may  well  give  pause  to  any  who, 


Waverly  Press,  Baltimore,  Md.,  June  9, 
out  material  alterations. 


From  Jour.  Wash.  Acad.  Sc.,  Feb.    19,  1928.    Repaged  with- 


POSSIBLE   ECONOMIC   SIGNIFICANCE  389 

basing  their  views  on  past  records  and  much  current  opinion,  see  in  the 
presence  of  such  parasites  merely  an  interesting  phenomenon. 

For  example,  it  is  now  found  that  the  presence  of  nemic  parasites 
not  infrequently  has  a  profound  effect  upon  the  reproductive  organs 
of  the  host,  a  limited  number  of  the  parasites  even  producing  complete 
sterility  in  a  host  otherwise  apparently  normal.  That  such  cases  in  their 
most  definite  form  have  thus  far  been  found  mainly  in  the  invertebrate 
phyla  does  not  invalidate  the  application  of  the  idea  to  vertebrates, 
even  were  such  cases  wholly  unknown  in  the  vertebrata, — which 
they  are  not.  Considering  the  well  known  universal  specificity  of 
certain  chemical  reagents, — chloroform  for  instance,  a  "universal" 
anaesthetic, — we  should  be  prepared  to  accept  without  very  much 
surprise  some  such  universal  specificity  in  the  action  of  some  hormones, 
particularly  sexual  hormones,  whose  origin  traces  back  to  comparatively 
simple,  but  fundamental,  ancestral  cell  phenomena. 

Again,  there  is  abundant  evidence  of  high  infant  mortality  in  a  great 
variety  of  animals  and  plants,  due  to  nematism.  This,  coupled  with 
our  ignorance  of  the  early  life  histories  and  food  habits  of  fishes,  even 
common  ones,  makes  it  unwise  to  ignore  the  possible  economic  impor- 
tance of  the  nemic  parasites  of  fishes. 

Many  other  examples  could  be  cited  of  the  multitudinous  and 
unexpected  ways  in  which  nemas  are  being  shown  beneficial  or  in- 
jurious to  mankind. 

Ascarophis  helix  n.  sp. 

fed £?/      "bio ""*&" Sgl-ia*— i.  The  thick  layers  of  the 

transparent,  colorless,  naked  cuticle  are  traversed  by  obvious  plain  transverse 
striae,  which  vary  markedly  in  different  portions  of  the  body.  On  the  head, 
however,  the  transverse  striae  are  hard  to  resolve;  yet  critical  examination 
of  the  striae  immediately  on  and  behind  the  lip  region  even  resolves  them 
into  rows  of  dot-like  elements.  In  this  region  the  crenations  of  the  contour 
seem  duplex,  four  double  crenations  a  short  distance  behind  the  head  occupy- 
ing 10  microns,  so  that  each  crenation  encompasses  about  1.25  microns. 
In  the  latitude  of  the  nerve-ring  the  striae  are  1.7  microns  apart;  thence 
backward  they  are  gradually  coarser  and  more  distinct,  each  striation 
becoming  a  double  line.  Furthermore,  it  is  soon  apparent  that  the  stria- 
tions  pass  around  the  body  in  the  form  of  right-handed  helices — coarser  and 
coarser,  and  more  oblique,  with  increasing  latitude,  so  that  at  the  base  of 
the  long  neck  the  coils  are  about  8  microns  apart  and  lie  at  an  angle  of 
about  23°  with  a  transverse  plane.  This  obliquity  increases  until,  near  the 
middle  [of  the  body,  it  reaches  a  maximum  of  about  30°  (Fig.  2).  Thence 
onward,  however,  the  obliquity  diminishes.  Somewhat  behind  the  middle 
of  the  body,  certain  coils  of  the  helix  fade,  so  that  the  other,  now  more  promi- 
nent, striae  are  as  much  as  20  microns  apart,  while  their  width  is  nearly 
two  microns, — namely  the  distance  apart  of  the  double  "lines"  representing 
the  striae.  This  "dropping  out,"  or  fading,  of  course,  is  evidence  of  the  exis- 
tence of  a  plurality  of  helicoid  "striae."  In  this  way  the  body  of  the  nema  takes 


390 


ASCAROPHIS   HELIX 


on  the  external  form  of  an  ordinary  multiple-threaded  screw.  Here,  in  the  mid- 
dle, the  contour  of  the  body  has  become  very  coarsely  and  very  pronouncedly 
compound-crenate.  The  more  pronounced  striae  come  to  subtend  twelve 
minor  ones  (Fig.  3).  Finally  near  the  tail  end,  the  more  pronounced  striae 
subtend  six  minor  ones  (Fig.  3) ;  this  is  near  where  the  body  is  bluntly  rounded 
off,  in  a  hemispherical-conoid  manner,  in  the  course  of  a  distance  equal  to 
about  one  and  one-half  body  widths  (Fig.  1).  At  first  sight  the  deceptive 
appearance  of  the  cuticle  toward  the  posterior  end  of  the  nema  suggests 
moulting,  and  consequent  wrinkling  of  the  cuticle.  Longitudinal  "striations," 
about  2  microns  apart,  due  to  the  attachment  of  the  mus- 
culature, are  visible  in  most  regions  of  the  body.  Posteriorly 
these  longitudinal  "striae"  are  still  slightly  oblique,  and 
this  slight  obliquity  extends  practically  to  the  terminus. 
There  are  no  cuticular  wings.  With  the  nema  in  profile 
the  lateral  chords  appear  about  one-seventh  as  wide  as  the 
body. 

The  groove-like  unarmed  " vestibule"  is  very  simple  and 
shallow, — about  as  deep  as  the  height  of  the  two  prominent, 
lateral,  forward-pointing,  conical  labial  projections  (Fig.  1, 
proj  #>).  The  vestibule  leads  through  the  slit-like  mouth 
opening  into  a  long,  uniform,  tubular  pharynx,  extending 
more  than  halfway  to  the  nerve-ring.  The  pharynx  is  a 
marked  feature  of  the  front  end,  though  it  is  so  transparent 
and  dimly  refractive  that  it  might,  perhaps,  under  some 
circumstances,  rather  easily  be  overlooked  (Fig.  1).  Van 
Beneden  seems  to  have  figured  the  pharynx;  Nicoll  not,  or 
at  least  not  definitely.  The  mouth  seems  to  lead  into  a 
minute  pharyngeal  or  vestibular  cavity,  not  very  much  wider 
than  the  amphids,  perhaps  six  to  eight  microns  wide, — a 
little  longer  dorso-ventrally  than  transversely.  The 
median  axil  between  the  two  lips  is  not  sharp  and  distinct. 
The  inner  surfaces  of  the  conical  labial  projections  are 
not  uniformly  rounded  and  striated,  like  the  outer  sur- 
faces,— for,  near  the  middle,  in  their  inner  lateral  lines 
or  fields  there  are  refractive  longitudinal  elements  ex- 
tending from  the  tips  back  to  the  mouth  opening.  It 
seems  quite  certain  that  there  is  an  axial  element  ex- 
tending to  the  apex  of  each  of  these  conical  projections, 
and  when  this  is  viewed  in  optical  section,  as  one  focuses 
from  front  to  back,  the  appearances  give  rise  to  the  opinion 
that  there  is  a  single  innervation  to  each  conical  pro- 
jection. One  sees  no  evidence  of  radial  musculature 
round  the  vestibule.  There  are  no  eyespots;  and  there  is  no  pigment  near 
the  head,  or  elsewhere  in  the  nema. 

Returning  now  to  the  profile  and  dorsal  views  of  the  head; — four  to  five 
microns  behind  the  tips  of  the  two  cephalic  projections,  exceedingly  minute 
openings  in  the  lateral  region  indicate  the  external  amphids.  As  viewed 
dorso-ventrally,  the  anterior  part  of  the  walls  of  the  pharynx,  without  diminish- 
ing much  in  thickness,  bend  together  and  nearly  meet  near  the  base  of  the 
vestibule,  thus  giving  rise  to  the  narrow  mouth  opening;  in  this  anterior 
portion  of  the  pharynx,  the  transverse  striation  is  less  apparent. 

Behind  the  pharynx  the  oesophagus  is  a  little  less  than  one-third,  at  the 
nerve-ring  about  one-fourth,  twice  as  far  back  as  the  nerve-ring  a  little  less 


Fig.  2. — Camera 
lucida  drawing  of 
an  oblique  view  of 
the  eight-fold  heli- 
coid  striae  of  As- 
carophis  helix,  at 
lat.  23°,  near  the 
beginning  of  the 
intestine.  The  an- 
astomosing occurs 
opposite  the  lateral 
chords. 


ORIGIN   OF   HELICOID   STRIAE 


391 


than  one-third,  and  then  again  soon — rather  suddenly  increasing — a  little 
more  than  one-third,  and  finally  is  one-half,  as  wide  as  the  corresponding 
portion  of  the  neck.  The  lining  of  the  oesophagus  is  a  rather  distinct 
feature  throughout  its  length,  and  finds  its  main  optical  expression  as  a 
somewhat  sinuous  axial  element.  The  musculature  of  the  oesophagus  is 
rather  fine.  Behind  where  the  above-mentioned  enlargement  takes  place 
there  is  a  considerable  amount  of  granular  matter  in  the  oesophageal  tissues. 


Fig.  3  Fig.  4 

Fig.  3.— Helicoid  striae  of^Ascarophis  helix  considerably  behind  the  middle  of  the 
body. 

Fig.  4.— Camera  lucida  drawing'of  the  contour  of  Ascarophis  helix  near  the  tail 
end  of  a  female. 

In  front  of  this  region  the  radial  fibers  are  of  a  finer  nature,  closer  together, 
and  the  granulation  much  less  apparent,  if  present  at  all;  in  other  words, 
there  is  a  distinct  change  in  the  structure  of  the  eosophagus  at  a  point  twice 
as  far  back  as  the  nerve-ring.  The  intestine  becomes  almost  at  once  two- 
thirds  as  wide  as  the  body;  it  is  separated  from  the  oesophagus  by  a  distinct 
cardiac  collum  somewhat  less  than  half  as  wide  as  the  body. 


Fig.  5. — Diagrams  illustrating  a  theory  of  the  mode  of  origin  of  helicoid  striae  through 
anastomosing  of  the  ordinary  transverse  striae  of  the  nemic  cuticle.  Let  1  represent 
seven  ordinary  annules  of  a  nemic  cuticle,  and  suppose  the  anastomosing  to  take  place 
on  opposite  sides  of  the  nema  at  the  places  indicated  by  the  arrows;  2  represents  the 
anastomosing  as  having  taken  place,  precisely  as  indicated  by  the  arrows  in  1 ;  while 
3  and  4  show  the  further  theoretical  transition  to  perfect  helices.  It  will  be  observed 
that  two  helices  are  formed.  Bilaterally  symmetrical  growth  would  necessarily  lead 
to  helices  of  even  number,  as  exemplified  in  Ascarophis.  See  also  Figs.  6  and  7. 


392 


ORIGIX   OF   HELICOID    STRIAE 


The  wall  of  the  intestine,  while  not  very  thick,  is  somewhat  irregular  in 
thickness,  the  lumen  appearing  zigzag.  At  places  the  wall  of  the  intestine 
is  one-fourth  as  thick  as  the  intestine  is  wide;  at  other  places  nearby  its 
thickness  may  diminish  by  two- thirds.  There  is  a  distinct  lining  to  the 
intestine,  apparently  made  up  of  "columnar"  elements  vertical  to  the  inner 
surface,  though  these  have  not  been  very  clearly  seen  (Fig.  8).  The  granules 
contained  in  the  intestinal  cells  are  rather  uniform  in  size,  but  their  histo- 
logical  characters  can  not  be  made  out  on  account  of  the  state  of  preservation 
of  the  specimen.  Well  forward,  near  the  blind  end  of  the  ovary,  the  intestine 
is  not  over  one-third  as  wide  as  the  body;  and  in  this  region  the  body  wall, 
including  the  cuticle,  occupies  about  one-fourth  the  radius,  of  which  amount 
the  vaguely  retrorse  cuticle  occupies  eight  microns  and  the  muscular  tissue 
fifteen  microns.  There  seems  to  be  a  very  short  rectum.  The  portion  of 
the  intestine  just  in  front  of  the  rectum  is  saccate,  and,  for  a  very  short  dis- 
tance about  half  as  wide  as  the  corresponding  part  of  the  body;  whereas 
in  front  of  this  enlargement  the  intestine  is  only  about  one-third  as  wide  as 
the  body. 


Fig.  6 


Fig.  7 


Fig.  6. — Should  two  ordinary  adjacent  annules  on  each  side  of  the  nema  behave  as 
shown  in  1,  the  result  would  be  four  helices;  four  such  would  originate  eight  helices. 
See  also  Fig.  7  and  Fig.  5. 

Fig.  7. — Should  anastomosing  take  place  simultaneously  in  successive  annules  oppo- 
site any  four  of  the  longitudinal  chords  a,  b,  c  and  d,  say  the  four  submedian,  or  the 
two  lateral  and  the  two  median,  the  result  would  be  four  helicoid  striae.  See  also 
Fig.  6. 

The  blind  end  of  the  anterior  ovary,  about  as  wide  as  the  distance  between 
two  of  the  adjacent  oblique  winds  of  the  cuticular  helix,  is  about  two-thirds 
as  far  behind  the  cardia  as  this  latter  is  behind  the  anterior  extremity.  In 
this  region,  in  the  body  cavity,  which  is  relatively  of  considerable  capacity, 
there  are  "floating"  organs  made  up  of  ellipsoidal  or  subspherical,  fine  granules, 
the  largest  of  which  are  about  eight  microns  in  diameter  (Fig.  8,  org  fluit). 
These  "loose"  organs  are  reminiscent  of  those  known  and  figured  in  some  of 
the  ascarids, — e.g.,  Ascaris  kukenthalii.  The  ovaries  lie  in  elongate  coils, 
and  at  first  contain  oocytes  about  four  microns  across,  which  soon  increase 
and  become  packed  in  the  ovaries  in  the  form  of  polyhedrons  whose  optical  con- 
tour is  often  hexagonal,  and  which  are  10  to  12  microns  across  where  the  ovary 
is  one-third  as  wide  as  the  body.  The  stretched-out  ovary  would  be  about 


DIAGNOSIS   OF   ASCAROPHIS   HELIX 


393 


twenty  times  as  long  as  the  body  of  the  nema  is  wide,  and  at  its  greatest 

width  about  one-third  as  wide  as  the  nema.     Sperms  have  not  been  seen, 

nor  has  the  extent  and  nature  of  the  oviduct  been  observed.     The  two 

uteri  are  filled  with  six  to  eight  hundred  ellipsoidal  eggs  about  one-third  as 

long  as  the  body  is  wide  and  averaging  40  X  24  microns.    For  a  short  dis- 

tance near  their  equator  the  eggs  are  practically  cylindrical.     The  shells 

are  thick  —  a  little  over  2  microns  —  and  structureless  looking;  are  of  uniform 

thickness  throughout;  and,  as  seen  in  the  uteri,  are  without  any  surface 

markings  or  appendages.     No  indications  were  seen  of  "two  flagellae  at  one 

pole,"  as  noted  by  van  Beneden  and  Nicoll.     It  is  possible  that  appendages 

might  arise  later,  e.g.,  from  some  vaginal  secretion  coagulated  during  deposi- 

tion.    The  eggs,  before  deposition,  contain  fairly  well  developed  larvae. 

There  is  a  single  ovijector  of  considerable  length  passing  inward  from  the 

vulva;  apparently  the  ovijector  is  several  times  as  long  as  the  body  is  wide, 

—  say  at  least  three  times.     Its  walls  are  thick  and  muscular;  viewed  in 

optical  section  it  is  nearly  one-third  as  wide  as  the  body,  being  somewhat 

flattened  when  collapsed,  and  so,  in  cross-section,  a  little  more  than  half 

as  wide  as  long.     Its  lining  is  thin 

and  strongly  refractive;  the  wall, 

when   seen  in  optical  section,  is 

glassy  internally  and   fibrous  ex- 

ternally.    The  vulva  is  a  transverse 

ellipsoidal  affair  near  the  middle 

of  the  body,  about  one-fifth  as  wide 

as  the  corresponding  portion  of  the 

body  and  interrupting  two  to  three 

of  the  spirals.     It  is  about  twice  as 

wide  as  long,  is  distinctly  marked, 

and  presents  a  double  refractive 

contour,     especially     posteriorly. 

The  excretory  pore  is  an  opening 

of  considerable  size,  taking  up  the 

space  of  about  three  annules  of 

the  cuticle.     For  a  short  distance 

the   tube   is    strongly  refractive, 

then  suddenly  becomes  almost  in- 

visible.     In   the   specimen  under 

examination  it  is  impossible  to  follow  it  far  enough  to  say  whether  in  its 

course  it  becomes  double  and  symmetrical  or  remains  single  and  asymmetrical 

(Fig.  1,  p  ex.) 

Diagnosis:  Ascarophis  having  a  length  of  13  mm.;  striae  helicoid,  the 
sub-cephalic  ones  very  fine  and  not  retrorse,  the  posterior  ones  very  coarse 
and  compound,  their  maximum  obliquity,  —  behind  the  nerve-ring,  —  30°; 
the  two  labial  projections  broadly  conoid;  pharynx  tubular,  1.1%;  tail 
convex,  and  rather  symmetrically  short-conoid,  0.2%;  eggs  without  polar 
filaments. 

Habitat:  Gills  of  the  fish,  Dasyatis  centrum,  —  Sting-ray.  G.  A.  MacCal- 
lum,  Woods  Hole,  Mass.,  August,  1927.  Hitherto  Ascarophis  has  been 
found  only  in  the  intestinal  canal  of  fishes.  The  plurality  of  helices  has 
probably  evolved  through  anastomosis;  this  anastomosis,  if  increased  in 
extent  and  systematized  as  shown  in  the  diagrams  (Figs.  5,  6  and  7)  could 
give  rise  to  helical  striae.  \  The  anastomoses  in  A.  helix,  as  far  as  seen,  are 
lateral. 


Mix ^^====^^ 

Fig.  8. — Somewhat  schematized  drawing  of  a 
cross-section  of  Ascarophis  helix,  taken  not  far 


UNGELLA  SECTA 

n.gen.  n.  sp. 

A  nemic  parasite  of  the  Burmese  Oligochaete  (earthworm), 
Eutyphoeus  rarus. 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XVIII 
BY  N.  A.  COBB 

Ungella  secta  n.  gen.  n.  sp. 

The  transparent  colorless  cuticle  is  traversed  by  transverse  striae,  about 
one  micron  apart,  hard  to  resolve  even  with  high  powers,  at  least  in  alcoholic 
specimens.  In  certain  stages  of  the  nema  the  striae  are 
much  more  (obvious  and  double  [in  jsize.  Though  inter- 
rupted, the  striae  are  not  altered,  on  the  lateral  fields, 
where  there  are  only  faint  single  wings — non-existent  or 
faint  on  the  neck  and  anterior  portion  of  the  body,  but 
somewhat  readily  seen  along  the  middle  of  the  body.  The 
very  slightly  oblique  longitudinal  striae,  due  to  the  at- 
tachment of  the  musculature,  are  more  readily  visible  than 
the  transverse  striae.  (Fig.  3,  str  longt)  Between  the 
longitudinal  striae  are  faint  rows  of  dots,  reminiscent  of 
the  cuticular  markings  of  Diplogaster, 

And  here  it  may  be  said  that,  though  valveless,  the 
oesophagus  also  is  reminiscent  of  Diplogaster;  and  that 
of  all  the  free-living  genera,  Diplogaster  is  that  to  which 
Ungella  seems  most  closely  related.  It  is  readily  conceiv- 
able that  the  submedian  duplex  onchium  (Fig.  1),  could 
have  been  evolved  from  an  armature  such  as  characterizes 
one  of  the  types  of  diplogastric  pharynx. 

Onchium.  The  duplex  onchium  of  Ungella  has  its  amalga- 
mated roots  mo  vably  imbedded  in  the  head  end  of  the  nema 
backward  for  a  distance  equal  to  two-thirds  the  width  of 
the  head  or  mo  re, 'it  is  assumed  therefore  that  this  represents 
the  depth  of  the  otherwise  unarmed  pharynx.  The  onchium, 
which  can  be  exserted  for  the  greater  part  of  its  length,  is  a  strong  refractive 
organ,  colorless  except  distally,  where  it  is  yellowish;  it  is  a  conspicuous  feature 
of  the  head,  especially  when  protruded.  The  two  equal  claws  of  the  onchium 
are  joined  rigidly  in  such  a  way  as  to  make  it  impossible  for  them  to  be  juxta- 
posed, and  their  internal  structure  makes  plain  that  they  represent  the  two 
ventrally  submedian  sectors  of  the  oesophagus.  Thus  the  onchium  and  its 


Fig.  1.—  Ungella 
secta.  Side,  dorsal 
and  end  views  of 
the  same  head. 
M'br,  the  intussus- 
ception membrane. 


•Waverly  Press,  Baltimore,  Md.,  June  19,  1928.    From  Jour.  Wash.  Acad.  Sc.,  Apr.  4,  1928.    Repaged  without 
material  alterations. 


MALE  AND    FEMALE    UNGELLA 


395 


"hilt"  have  the  general  form  of  the  ulti- 
mate two-clawed  segment  of  a  beetle's 
tarsus.  (See  Fig.  1.)  Rather  weakly 
developed  retractor  muscles  are  at- 
tached to  the  'amalgamated  onchial 
apophyses.  It  seems  not  unlikely  that 
the  caudal  "suckers"  may  also  aid — as 
a  base  of  resistance — in  the  use  of  the 
onchium,  the  object  of  which  must  be 
to  claw;  it  must  wound  by  clawing, 
hence  the  specific  name  secta.  When 
the  onchium  is  withdrawn  and  at  rest, 
as  in  the  female  of  Figure  2,  the  outer 
or  distal  parts  of  the  two  claws  rest  in 
special  lateral  depressions  on  the  out- 
side of  the  front  of  the  head  (see  concav 
Fig.  1)  and  to  that  extent  are  not 
withdrawn  into  the  head. 

Oesophageal  glands.  The  median 
dorsad  pore  in  the  front  of  the  head, 
por  dsl,  is  the  exit  of  a  large  well  de- 
veloped special  cervical  gland,  gl  crv. 
The  excretory  pore  of  the  renette,  p 
ex,  is  farther  back  and  ventral.  There 
is  an  almost  imperceptible  short  alter- 
ation in  the  oesophageal  lining  be- 
tween the  fore  and  after  parts  of  the 
oesophagus, — probably  the  vestige  of 
a  median  bulb.  The  indistinctly  cla- 
vate,  posterior,'non-valvate,  oesopha- 
geal swelling  contains  a  single,  bright, 
refractive,  three-micron  nucleus  near 
the  base  in  the  dorsal  sector,  proving 
the  presence  of  an  oesophageal  gland. 
Radial  oesophageal  muscles  are  only 
faintly  to  be  seen. 

Intestine.  A  cross-section  of  the 
intestine  cuts  through  only  about  two 
relatively  large  cells.  The  refractive 
lining  of  the  intestine  often  is  distinctly 
to  be  seen.  In  the  front  portion  of  the 
body  the  wall  of  the  intestine  is  hardly 
as  thick  as  that  of  the  body;  here  the 
lumen  of  the  intestine  often  is  more 
than  twice  as  wide  as  the  thickness  of  the  intestinal  wall. 


org  wt?. 


'sub  cut      'mac 

Fig.  2.— Male 
tna  and   female    U. 
secta.    From  al  - 
coholic      earth- 
worm        speci- 
mens. All  nemas 
adult,      females 
outnumbering  males. 


X400 


396 


"SUCKERS" 


Renette.  The  renette  duct,  dct  ex,  is  distinctly  refractive  and  nearly  two 
microns  across;  it  passes  inward  at  right  angles  to  the  ventral  surface  and 
then  turns  backward  on  the  left  side  and  becomes  narrower  and  apparently 
bifurcate. 

Caudal  "Suckers."  The  tissue  composing  the  mouths  of  the  two  lateral 
caudal  "suckers"  is  comparatively  structureless  looking,  and  externally  par- 
takes of  the  general  character  of  the  cuticle.  These  two  large  lateral  open- 
ings, found  on  the  tail  of  adults  of  both  sexes,  when  viewed  dorso-ventrally 
are  seen  to  lead  inward  and  forward  into  two 
well  developed  pockets  or  "suckers,"  so  massive 
that  this  portion  of  the  tail,  in  the  median  aspect 
appears  about  50  per  cent  wider  than  the  portion  of 
the  tail  immediately  behind  (Fig.  3,  org  suci). 
The  cavity  of  each  organ  is  lined  with  thick  striated 
tissue  whose  most  obvious  elements  are  arranged 
at  right  angles  to  its  inner  surface,  which  presents 
a  very  definite  internal  sectional  contour,  due  to 
the  refractiveness  of  this  tissue;  so  that  the  whole 
organ  is  a  relatively  conspicuous  affair.  A  strand 
(contractile?)  leading  forward  from  each  "sucker" 
into  the  corresponding  lateral  chord  is  at  first 
rather  wide,  then  narrows  (text  org  suet,  Fig.  3). 
The  "suckers"  seem  to  make  their  appearance  on 
both  sexes  at  the  last  moult  (Fig.  4). 

Gonads.  The  elevated  transverse  vulva  ap- 
parently is  not  very  wide.  Near  the  flexure  the 
gonad  presents  a  spermatheca,  spmth,  containing 
numerous  spherical  sperms  of  such  a  size  that 
about  a  dozen  would  be  required  to  span  the 
body  diameter.  These  possess  refractive,  faintly 
lobed  nuclei,  indicating  the  presence  of  a  small 
number  of  chromosomes — probably  about  five. 
Contained  in  the  uterus  of  adult  females,  as  a  gella  secta>  showing  *n  *he 
rule,  is  a  single  thin-shelled,  smooth  egg,  ov,  lower  part 
about  one  and  one-half  times  as  long  as  the  body 
is  wide  and  about  one-third  as  wide  as  long.  No 
segmented  egg  has  been  seen  in  the  uterus.  The  blind  end  of  the  ovary 
lies  between  the  caudal  "suckers"  or  somewhat  farther  forward.  From 
the  blind  end  of  the  ovary  forward  the  oocytes  very  soon  become  smaller, 
as  if  by  division,  and  not  far  from  the  anus  are  arranged  several  abreast, 
and  so  continue,  increasing  meanwhile  in  size,  for  a  good  fraction  of  the  dis- 
tance to  the  vulva;  thence,  owing  to  increased  size,  they  are  arranged  single 
file,  each  ovum  cylindroid  and  somewhat  longer  than  wide. 


X800 


sir  long  it 


tf^t  org  suet 


owyt. 


strJfflff/t 


car  org  suet 


as  org  suet  ? 


tnaw  .  . 

Fig.   3. — Ventral  view  of 
the   post-anal  region  of  Un- 


two  lateral  pockets  or  suck- 
ers, cav  org  suet. 


DIAGNOSES  397 

The  male.  The  relatively  large  gubernaculum,  gub,  is  single,  rather  shallow, 
nearly  straight,  and  extends  inward  nearly  at  right  angles  to  the  ventral  sur- 
face, so  that  its  proximal  end  is  considerably  dorsad  of  the  body  axis.  It 
appears  quite  as  massive  as  the  two  equal  spicula,  and  has  the  form  of  a  rela- 
tively very  broad,  shallow,  somewhat  boat-like  trough,  deepest  amidships, 
its  depth  being  about  one-third  'its  length.  The  long 
narrow  bursa,  brs,  presents  seven  whiplash-like  ribs  (1-7, 
Fig.  2)  extending  into  each  of  the  colorless,  thin,  glassy- 
looking,  ventrally  submedian,  bursal  expansions  of  the 
cuticle. 

Since  the  suckers  are  common  to  both  sexes,  they  can 
hardly  be  considered  secondary  sexual  organs.    Figure  4, 
X  800     1 -•:"''         derived  from  one  of  the  few  immature  specimens  thus  far 
Fig.  4.— Ventral     seen,  seems  to  indicate  that  these  interesting  organs  come 
view  of  the  suckers     into  existence  at  the  last  moult,  for,  just  previous  to  the  last 

°ust  beTre^theTast      m°Ult>  they  ^^  immature  or  "embryonic."     It  seems 
moult6  °  hardly  possible  that  these  organs  can  be  homologous  with 

the  phasmids;  nor  does  it  seem  possible  to  link  them  with 
such  ventral  suckers  as  occur  for  instance  on  male  Heterachids.  In  short, 
further  observation  is  needed  fully  to  determine  their  function. 

Habitat:  Body  cavity  and  muscles  of  the  earthworm,  Eutyphoeus  rarus; 
fide  Mr.  G.  E.  Gates,  to  whom  the  discovery  of  the  nema  is  due.  Locality, 
Prome,  Burma,  India. 

Ungella,  n.  gen. 

Genus  Diagnosis:  Amphigonic  onchia  hooked  protrusile,  dorsally  arcuate; 
and  special  cervical  gland;  oesophagus  degenerate-diplogastroid;  adults 
with  posterior  lateral  pockets  or  "suckers;"  'm  and  'f ;  males  with  two  equal 
spicula  and  a  gubernaculum,  and  an  elongate  pre-  and  post-anally  ribbed 
bursa.  Parasitic  in  earthworms.  Proposed  as  type  species  is: 

Species  Diagnosis:  Flexible-tailed  ungellas,  dimensioned  as  in  the  formulae 
and  illustrations,  with  two  practically  submedian,  amalgamated  onchia 
(ungellae),  having  the  form  of  the  final  joint  of  a  beetle's  tarsus;  cervical 
gland  just  behind  the  cardia,  its  outlet  dorsad  on  the  lip  region;  pockets  or 
suckers  not  far  in  front  of  the  middle  of  the  tail;  external  amphids  more  or  less 
circular  and  opposite  the  base  of  the  pharynx;  oviparous;  males  with  three 
pre-  and  four  post-anal  slender  ribs  to  the  bursa,  as  shown  in  Figure  2 ;  pos- 
terior part  of  the  tail  cylindroid,  fine  yet  blunt, — in  the  male  distinctly  set 
off. 

Only  a  more  careful  study  of  the  nemas  thus  far  described  as  para- 
sitic in  earthworms  can  determine  the  nature  and  limits  of  most  of  the 
genera  and  species  that  have  been  proposed  for  their  reception. 

For  literature  consulted  see  the  list  of  Pierantoni  (Boll.  Soc.  Nat. 
Napoli,  1915,  p.  150-3)  and  Baylis  &  Daubney  (Synopsis,  1926). 


A  NEW  SPECIES  OF 

THE  NEMIC  GENUS  SYRINGOLAIMUS 

With  a  note  on  the  fossorium  of  nemas 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XIX 

BY  N.  A.  COBB 

The  writer's  collection  of  Syringolaims  shows  them  to  live  on  tem- 
perate and  tropical  sea  coasts  in  many  parts  of  the  world.  Among 
other  places,  his  Syringolaims  (1888-1927)  represent  the  East  Indies 
(Larat),  Polynesia  (Noumea,  Hawaii),  the  Atlantic  and  Pacific  Coasts 
of  Panama,  the  Atlantic  Coast  of  the  United  States,  and  the  English 
Channel.  The  manuscript  record  of  these  collections  contains  full 
descriptions  of  a  number  of  new  but  unpublished  closely  related  species. 

Our  knowledge  of  this  genus  has  increased  but  little  since  de  Man 
described  the  type  species,  his  S.  striatocaudatus.  The  present  publi- 
cation adds  information  concerning  (1)  the  labial  papillae,  (2)  the 
amphids,  (3)  the  phasmids  (?),  (4)  the  fossorium,  (5)  the  intestine, 
(6)  the  male  gone,  (7)  the  food  habits,  and  (8)  the  geographic  distribu- 
tion. 


Syringolaimus  smarigdus,  n.sp.  |;J      *%$     *%% 

The  transparent,  colorless  cuticle  is  traversed  by  plain  transverse  striae 
very  difficult,  or  almost  impossible,  to  resolve,  which  are  not  altered  on  the 
lateral  fields.  Faint  traces  of  wings  occur,  beginning  near  the  head  and  end- 
ing on  the  tail.  Longitudinal  "striae,"  due  to  the  attachment  of  the  muscula- 
ture, are  visible  in  nearly  all  regions  of  the  body.  No  series  of  pores  have 
been  seen  in  the  cuticle.  Of  the  highly  mobile  lips  there  probably  are  three, 
but  they  are  no  more  than  sub-distinct,  and  are  small  and  somewhat  rounded. 
The  pharynx  is  armed  in  front  with  three  duplex  (somewhat  lobster-claw- 
like),  in  profile  somewhat  inverted-comma-shaped,  subacute  odontia  (Fig. 
1,  mnd)  having  an  outward  throw  of  about  180°,  a  movement  seen  on  more 

Waverly  Press,  Baltimore,  Md.,  June  9,  1928.  From  Jour.  Wash.  Acad.  Sc.,  May  4,  1928.  Repaged  without 
material  alterations. 


MALE    SYRINGOLAIMUS    SMAR1GDUS 


gld  & 


Fig.l 


400  ANATOMY    OF   SYEINGOLAIMUS 

than  one  occasion  to  occur  every  second  or  so  when  the  live  nema  was  placed 
under  the  microscope  under  slight  pressure  (Fig.  1).  The  cross-section  of  the 
pharynx  is  round-triquetrous,  almost  circular,  with  faint  subordinate  mark- 
ings in  the  middle  of  each  side,  indicating  on  the  whole  a  hexagonal  structure. 
There  are  no  eyespots.  The  base  of  the  pharynx  may  be  surrounded  by  a 
very  faint  ellipsoidal  swelling.  There  is  only  a  faint  pharyngeal  muscular 
swelling,  though  there  are  fairly  well  developed  mandibular  muscles,  lying 
along  the  outside  of  the  pharynx  (Fig.  1,  msc  mnd).  There  is  a  rather  distinct 
but  small  conoid  cardia,  one-third  as  wide  as  the  base  of  the  neck,  or  less. 
The  ventriculus  stains  differently  from  the  remainder  of  the  intestine,  showing 
a  distinct  function  to  be  discharged  here ;  in  the  li ving  condition  however  the 
ventriculus  appears  somewhat  "structureless"  (vntrc).  The  granules  in  the 
cells  of  the  intestine  are  of  several  distinct  kinds:  some  of  them  are  colorless 
(grn  trnsp  int),  others  are  emerald-green  (grn  vrd  int) — hence  the  specific 
name  smarigdus;  none  are  birefringent.  The  content  of  the  intestine  is 
usually  reddish  or  greenish,  and  often  is  derived  specifically  from  an  alga  be- 
longing to  the  family  Half siae  (Fig.  3) ,  among  which  specimens  of  Syringolaimus 
smarigdus  are  often  found.  There  is  no  prerectum.  From  the  somewhat 
elevated  lips  of  the  anus,  of  which  the  anterior  lip  is  the  more  elevated, 
the  cutinized  rectum  extends  inward  and  forward  a  distance  about  equal  to 


Fig.  2. — Snails,  natural  size,  covered  with  a  very  dark  green  "pile"  or  "felt"  consist- 
ing of  microscopic  algae.  The  nature  of  this  growth  is  illustrated  in  Fig.  3. 

two-thirds  of  the  corresponding  body  diameter.  The  lateral  chords  enlarge 
from  one-fifth  (terminad)  to  one-half  (mediad)  as  wide  as  the  body.  From 
the  medium-sized  continuous  vulva,  the  cutinized  vagina  leads  inward  at 
right  angles  to  the  ventral  surface  three-fifths  the  way  across  the  body.  The 
uteri  contain  only  one  egg  at  a  time,  are  straight,  three  to  four  times  as 
long  as  the  body  is  wide,  and  from  one-fourth  to  one-sixth  as  wide  as  long. 
The  two  opposite,  equal,  symmetrically  arranged  ovaries,  about  half  as  wide 
as  the  body,  are  reflexed  about  two-thirds  the  distance  back  to  the  vulva  and 
contain  ten  to  fifteen  ova,  mostly  in  single  file.  The  elongate  egg  may  be 
3  to  4  body-widths  long,  appears  relatively  narrow,  and  seems  to  be  deposited 
before  segmentation. 

§;|      }£f  •     ^ 4-7r^.3' ' '  •  JjJ^-XJ.eswm     The  single  gubernaculum  (gub} 

may  consist  of  two  arcuate,  subslender,  parallel,  amalgamated  pieces,  and  is 
rather  closely  applied  to  the  spicula.  Phasmids(?)  (Fig.  1)  occur  on  the 

Fig.  1  .—Male  of  Syringolaimus  smarigdus,  together  with  four  different  views  of  the 
head  end.  Below,  a  diagrammatic  drawing  of  the  front  view  of  the  head.  Above,  three 
sketches  showing  different  attitudes  of  the  "mandibles"  or  fossores.  The  fossores  are 
also  shown  in  both  the  other  illustrations.  The  lettering  of  the  illustrations  consists 
of  self-explanatory  abbreviations  arranged  in  the  Latin  order;  grn  vrd  int — granulum 
viride  intestinalis,— green  granule  of  the  intestine;  etc. 


FOSSOR1UM    OF   NEMAS 


401 


lateral  lines  near  the  middle  of  the  tail  on 
both  sexes.  While  there  is  no  distinct  bursa, 
the  cuticle  is  faintly  thickened  in  the  sub- 
median  region  near  the  anus,  possibly  a  very 
rudimentary  bursa. 

Habitat:  Common  among  minute  filamen- 
tous algae  on  the  surface  of  marine  mollusks, 
especially  the  snail  Alectrion  obsokta  (Fig.  2). 
Also  found  in  sand  on  beaches,  and  in  sand 
in  several  feet  of  water  off  shore.  Woods 
Hole  region,  1916  to  1927.  There  is  good 
reason  to  suppose  it  ranges  both  north  and 
south  from  Woods  Hole  along  the  Atlantic 
Coast.  It  occurs  in  beach  sand  from  near 
Falmouth;  and  in  clear  white  sand  in  five 
feet  of  water  in  a  cove  at  the  entrance  to 
Buzzard's  Bay;  also  at  Waquoit,  Mass., 
among  algae  on  the  shell  of  the  living  snail, 
Alectrion  obsoleta  (Nassa) ;  and  on  the  shells 
of  live  snails  from  the  Eel  Pond  at  Woods 
Hole.  Its  food  seems  always  to  be  vegetable 
matter,  and  in  many  cases  consists  entirely 
of  the  contents  of  the  cells  of  a  microscopic 
alga  belonging  to  the  genus  Ralfsia  (?). 

OUTWARD  ACTING  NEMIC  "MANDIBLES" 


Fig.  3.— Slight  portion  of  the 
algal  growth  from  the  snails  shown 
in  Fig.  2,  broken  or  dissected  away. 
Below  is  the  shell  of  the  mo  Husk. 
On  it  an  "incrustation,"  orange  in 
color,  consisting  of  an  alga  belong- 
ing to  the  family  Ralfsiae,  prob- 
ably to  the  genus  Ralfsia.  On  this 
incrustation  there  is  a  thick  felt- 
like  growth,  consisting  of  blue- 
green  and  yellow-green  algae. 
Syringolaimus  smarigdus  feeds 
upon  the  orange-colored  alga, 
which  it  can  reach  only  by  digging 
through  the  green  algal  growth 
above. 


The  writer's  study  of  the  attitudes  in 
which  the  mouth  parts  became  fixed  led 
to  the  conclusion  that  in  Axonolaimus 
and  its  relatives,  as  well  as  in  a  large 
number  of  other  nemas,  the  onchia  (and 
odontia)  had  an  outward  throw.  If  so,  it 
was  an  obvious  deduction  that  these 
organs  were  digging  organs,  for  which 
the  word  f  ossor2  seems  indicated.  This  deduction  led  the  writer  long 
ago  to  introduce  into  generic  names  of  such  nemas  root  words  indi- 
cating a  digging  function  on  the  part  of  the  mouth  organs,  as  for 
instance  in  the  genus  names  Scaptrella,  Diploscapter. 

It  is,  however,  difficult  to  observe  these  organs  in  operation,  and 
hence  of  interest  to  record  that  such  organs  have  been  seen  in  action 
in  a  Syringolaim  (Fig.  1),  and  furthermore  that  S.  smarigdus  has  been 
observed  under  conditions  constituting  strong  additional  circum- 
stantial evidence  that  these  organs  are  verily  digging  organs.  S. 

*  F  ossor  (plural,  fossores;  collective,  fossorium);  a  tool  or  organ  used  for  digging, 
usually  existing  in  a  plurality  and  acting  symmetrically  outward  from  a  plane  or  axis. 
Related  to  "fossorial" — said  of  animals  that  dig. 


402  SYRIXGOLAIMUS    DIGS 

smarigdus  is  found  in  algal  "incrustations"  of  the  family  Ralfsiae, 
and  probably  genus  Ralfsia.3  It  is  very  apparent  that  the  nema  feeds 
upon  the  Ralfsia,  for  the  color  and  structure  of  the  contents  of  the  cells 
of  this  alga  are  strikingly  characteristic,  and  the  intestinal  content  of 
the  associated  Syringolaims  not  only  has  exactly  the  same  color,  but 
frequently  is  otherwise  of  such  a  character  that  it  could  be  derived 
only  from  the  interior  of  the  Ralfsia  cells.  Often,  however,  there  are 
scattered  foreign  birefringent  particles  (carbonate  of  lime)  mixed  with 
the  ingested  food;  but  these  birefringent  particles  are  similar  to  those 
found  among  the  filaments  of  the  Ralfsia,  and,  taking  into  account 
the  relative  size  of  the  mouth  parts  of  the  Syringolaim,  it  is  very 
natural  to  suppose  that  some  of  this  foreign  matter  would  be  taken  in 
with  the  food. 

No  one  had  previously  explained  the  precise  nature  of  the  mouth 
organs  of  Syringolaimus.  They  consist  of  three  small,  arcuate,  more 
or  less  acute  odontia  with  a  spirally  outward  throw,  well  adapted  to 
boring  and  digging  (Fig.  1).  Now,  it  so  happens  that  the  location  and 
structure  of  the  incrustation  formed  by  the  Ralfsia  wTould  require 
digging  on  the  part  of  the  nema  in  order  to  obtain  food  from  it,  for  the 
Ralfsia  incrustation  on  the  snail  shells  (Alectrion}  is  usually  overgrown 
with  a  thick  comparatively  impenetrable  felt  of  filamentous  green 
algae  (Fig.  3) ;  hence  the  Ralfsia  can  be  reached  by  the  Syringolaimus 
only  by  digging. 

The  snail,  Alectrion  obsoleta  (Nassa),  lives  between  tide-marks  and 
hence  twice  daily  is  exposed  to  the  air,  and  on  each  such  occasion  any 
algal  growth  on  it  naturally  dries  up  more  or  less.  Here  then  is  an 
additional  complication  hi  the  environment  of  the  Syringolaim — a 
highly  and  rapidly  variable  temperature  and  salinity.  It  is  reason- 
able to  suppose  these  unusual  circumstances  might  give  rise  to  a  pecu- 
liar nemic  form  adapted  to  the  environment.  Thus  a  clue  is  found  to 
the  marked  peculiarities  of  form  and  structure  noted  in  Syringolaimus. 

3  Ralfsia;  fide  Dr.  I.  F.  Lewis. 


THE  CHROMATROPISM  OF  MERMIS 
SUBNIGRESCENS 

A  Nemic  Parasite  of  Grasshoppers 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOQY  XX l 

BY  N.  A.  COBB 

The  adult  female  Mermis  subnigrescens,  when  ripe  for  ovijection, 
has  away  of  moving  her  head  in  more  or  less  horizontal  curves; — her 
head,  directed  skyward,  is  waved  in  "circles,"  now  clockwise,  now  the 
reverse.  This  seemingly  purposeful  behavior  occurs  when  she  emerges 
from  the  soil  and  while  she  is  ascending  the  herbage  to  deposit  her  eggs. 
Inasmuch  as  the  head  of  the  egg-laying  female, — unlike  that  of  the 
young  female  as  well  as  that  of  the  male  (neither  of  which  ever  quits 
the  subterranean  darkness), — contains  reddish  transparent  pigment 
rather  definitely  distributed  with  reference  to  certain  cephalic  nerves, 
the  question  arose  whether  we  do  not  have  here  a  phototrope2  and  an 

1  Reprinted  from  the  JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES,  Vol.  19. 
No.  8,  April  19,  1929. 

2  It  is  suggested  that  the  mechanisms  through  whose  activation  the  responses  of 
organisms  termed  tropisms  find  expression  be  called  "tropes;" — "tropism"  to  be  taken 
in  almost  any  of  its  more  or  less  well  accepted  meanings. 

These  meanings  (interpretations  of  various  investigators,— see  Mast,  1915)  vary  all 
the  way  from  (1)  "an  inherent  tendency  to  respond"  (Standard  Dictionary),  to  (2)  an 
"irresistible"  or  "predictable"  orientation  as  definite  and  mechanical  as  that  of  a  magnetic 
needle;  but  whatever  the  accepted  interpretation,  the  reaction-mechanism  must  always  be 
present,  and  be  a  system  of  intimately  connected  elements  or  organs,  as  is  the  digestive 
system,  for  instance,  or  the  excretory  system.  Since  we  have  for  this  system  of  inti- 
mately connected  elements  no  inclusive  single  descriptive  term,  and  since  it  is  found 
highly  convenient,  or  even  necessary,  for  purposes  of  thought  and  discussion  mentally 
to  "isolate,"  and  separately  to  denominate,  the  digestive  system  or  enteron,  and  other 
systems,  it  is  suggested  that  in  behavior  studies  a  like  situation  be  met  by  a  similar, 

Waverly  Press,  Inc.,  Baltimore,  Maryland,  June,  19SO 


404  PHOTOTROPE 

affirmative  answer  was  forecast,  for  the  obvious  reason,  among  others, 
that,  as  the  pigment  must  absorb  certain  light  frequencies  and  transmit 
others,  the  absorption  might  well  result  in  some  such  changes  of  energy 
as  characterize  vision.  Very  suggestive  also  is  the  fact  that  the  trans- 
parent, colorless  parts  of  the  head  immediately  in  front  of,  and  along- 
side, the  suspected  phototrope  condense  light  rays  upon  it.  (See 
Fig.  1.) 

Previous  experiment  showed  the  spectrum  frequencies  concerned  in 
bringing  about  ovijection  in  this  nema  probably  to  be  some  of  those 
in  the  light-blue  and  low  violet  region  of  the  spectrum,  together  with 
red  (also  infra-?).3  It  would  therefore  be  natural  to  suspect,  under 
all  the  circumstances,  that  the  cephalic  pigment  characteristic  of  the 
adult  female  absorbs,  and  "makes  use  of,"  the  frequencies  present 
just  previous  to  and  during  ovijection.  Hence  a  wish,  (1),  to  deter- 
mine what  frequencies  are  present  during  and  just  previous  to  natural 
ovijection;  and,  (2)  to  determine  what  frequencies  are  absorbed  by  the 
cephalic  pigment. 

In  this  field  comparatively  little  seems  to  have  been  published, 
though  somewhat  pertinent  papers  by  Crozier,  Mast,  and  others  exist. 
Investigators  have  been  mainly  occupied  with  the  optics  of  the  various 
colorless,  transparent,  organic  elements;  the  relative  location  and 
probable  function  of  certain  pigments,  usually  dark  or  black  (opaque) ; 
and  the  "migration"  and  other  changes  of  pigment,  such  as  visual 
purple,  due  to  the  action  of  light;  and,  of  course,  with  the  associated 
nervous  and  contractile  elements.  Little  has  been  published  with 
regard  to  tropism  definitely  due  to  the  absorption  of  rays  of  a  particular 
frequency  solely  by  transparent,  colored  pigment  (other  than  visual 

but  if  possible  better  (to  wit  monosyllabic),  terminology.  The  advantages  of  a  mono- 
syllable from  which  short,  convenient  adjectives,  verbs,  adverbs  and  other  nouns  can 
readily  be  derived,  are  almost  too  obvious  to  need  mention, — tropic,  tropically,  to  trope, 
troping,  etc.,  etc.  Most  helpful,  perhaps,  will  be  its  use  as  a  component,  e.  g.,  in 
"chromatrope." 

Primarily  "trope"  denotes  action, — action  that  is  in  progress  rather  than  completed. 
By  metonymy  the  word  denoting  an  action  (here,  what  is  called  a  reaction)  may  be 
applied  to  the  (re)action-mechanism,  i.e.,  in  the  present  case,  to  the  responding  system 
of  intimately  connected  organs. 

Following  this  suggestion,  we  may  speak  of  a  reaction  mechanism  that  aids  or  causes 
an  organism  to  face  toward  or  away  from  light,  as  a  phototrope;  a  reaction  mechanism 
used  in  orientation  with  reference  to  gravity,  a  geotrope,  etc.,  etc.,  etc.,  etc.;  thus  the 
statocystic  mechanism  of  crustaceans  is  a  species  of  geotrope. 

Accordingly,  certain  cephalic  apparatus  of  Mermis  subnigrescens  is  here  spoken  of  as  a 
phototrope;  or,  better,  because  more  specific,  as  a  chromatrope, — inasmuch  as  its  reac- 
tions apparently  are  to  definite  frequencies  (colors)  of  the  solar  spectrum.  Glaucotrope 
y\avKO(7  =  blue)  may  prove  to  be  even  more  precise. 

3  Species  of  Mermis.    Journ.  Parasitology,  8 :  66.    1926. 


STRUCTURE  OF  THE  CHROMATROPE 


405 


purple)  located  definitely  with  reference  to  nerves,  these  nerves  them- 
selves so  located  as  possibly  to  be  sensory. 

SPECTROSCOPIC  TEST  OF  THE  PRESUMPTIVE  CEPHALIC  CHROMATROPE  OF 

Mermis  subnigrescens 

One-third  of  a  millimeter  of  the  front  end  of  an  adult  female  Mermis 
subnigrescens,  including  the  head,  was  ligated  and  cut  off,  and  then 
mounted  on  a  microscope 
slide  in  water.  The  head 
was  examined  under  a  1.5 
mm.  apochromatic  micro- 
scope objective,  having  a 
similar  objective  as  a  con- 
denser, in  such  a  way  that 
the  image  would  fill  as  much 
as  possible  of  the  micro-  ^f  fit 
scope  field  with  the  color  of 
the  pigment.  (See  Fig.  1.) 
The  microscope  was  fitted 
with  a  spectroscopic  eye- 
piece. 

Sunlight  was  taken  from 
a  flat  planished  aluminum 
reflector  placed  so  that  a 
maximum  of  sunlight  was 
reflected  through  both  in- 
struments,—^., the  above 
apochromatic-micro  -spec- 
troscope  and  a  comparison 
spectroscope.  The  pig- 
mented  tissue  was  brought 
into  focus,  and  then  the  iris 
diaphragm  of  the  micro- 
scope thrown  open,  so  as 
to  admit  a  "flood"  of  light. 
This  produced  a  spectrum 
fairly  readily  seen  in  a 
darkened  room,  notwith- 
standing the  very  high 
magnification. 

Much  of  the  violet  end 
of  the  spectrum  (well  into 


X200 

Figure  1.  Head  end  of  Mermis  subnigrescens, 
showing  the  chromatrope.  os,  mouth;  ppl  (2),  the 
two  lateral  so-called  "papillae;"  amph,  amphid; 
nrv  chrtrp,  nerves  of  the  chromatrope;  lum  oesoph, 
lumen  of  the  oesophagus;  pgmt  rub,  reddish  pig- 
ment of  the  chromatrope;  chrd  md,  median  chord; 
annnrv,  nerve-ring;  msc,  body-wall  muscles;  cut, 
cuticle;  oe,  oesophagus;  ppl  subm  (4),  the  four 
submedian  papillae;  nrv  amph,  nerve  of  the 
amphid;  ar  mcrscp,  shows  the  circular  area  of  the 
microscopic  field  that  was  tested  spectroscopically ; 
pgmt  lut,  orange-colored  pigment  of  the  chroma- 
trope;  chrmtrp,  chromatrope;  chrd  lat,  lateral 
chord;  sub  cut,  the  thick  subcuticle;  crbrm,  the 
cerebrum;  trphsm,  anterior  end  of  the  trophosome. 


406  ABSORPTION  BY  THE  CHROMATROPE 

the  blue)  was  absorbed  to  a  very  considerable  degree  by  the  living 
cephalic  pigment  of  the  Mermis  subnigrescens.  The  microscope  field 
was  never  completely  and  uniformly  filled  with  the  color  of  the 
pigment.  There  were  streaks  at  each  margin  of  the  field,  and  another 
through  the  middle,  that  showed  little  color  (see  Fig.  1),  so  that 
doubtless  the  absorption  was  not  so  pronounced  as  would  be  obtained 
by  dissolved  pigment  of  equal  density  filling  the  entire  field  of  the 
microscope. 

A  satisfactory  demonstration  was  made  by  placing  the  object  under 
the  microscope  so  as  to  produce  absorption,  and  after  the  spectra  had 
been  arranged  for  comparison,  suddenly  removing  the  pigmented 
tissue.  The  effect  produced  by  this  instantaneous  change  was  very 
pronounced.  The  blue  and  violet  region  of  the  spectrum,  hitherto 
obscured  by  absorption,  of  course  instantly  assumed  the  same  colors 
as  in  the  comparison  spectrum. 

There  seemed  also  to  be  some  absorption  in  the  outermost  part  of 
the  red  of  the  visible  spectrum,  but,  if  so,  it  was  very  slight.  No 
absorption  was  noticed  in  the  orange,  yellow  and  green,  and  little  if 
any  in  the  bluish  green. 

The  experiment  was  particularly  satisfactory  in  that  the  pigment 
was  in  a  living  condition.  True,  the  head  had  been  ligated  and  cut  off 
immediately  before  the  spectroscopic  examination,  but  from  much 
experience  it  is  known  that  such  a  head  continues  to  "live"  and  move 
anywhere  from  a  few  hours  to  a  day,  or  even  more. 

Phototropes  of  somewhat  the  character  here  described  probably 
occur  in  the  cervical  region  of  many  other  nemas,  particularly  free- 
living  ones, — the  outer  tissues  of  the  neck  serving  as  a  cylindrical  lens 
for  condensing  light  upon  the  pigmented  tissues.  Aquatic  nemas  so 
situated  as  to  utilize  light  rays  penetrating  water,  not  infrequently 
present  structures  that  may  be  suspected  to  be  phototropes, — now 
that  we  have  a  clue  to  the  nature  of  such  structures  in  this  phylum. 
These  primitive  phototropes  may  well  have  been  the  forerunners  of 
the  more  highly  developed  phototropes,  ocellate  systems,  of  certain 
nemas  (e.g.  Enchelidium). 

A  general  review  of  the  nature  and  relationships  of  localized  trans- 
parent pigments  in  organisms  in  the  light  of  the  foregoing  experiment, 
may,  perhaps,  suggest  new  ideas  and  experiments  with  regard  to  their 
functions  both  in  animals  and  plants. 


EFFECT  OF  INFRA  RED  407 

NATURAL  CONDITIONS  UNDER  WHICH  Mermis  subnigrescens 

DEPOSITS  ITS    EGGS 

At  Woods  Hole,  Mass.,  U.  S.  A.,  on  July  28,  1928,  from  long  before 
daylight  up  to  10  o'clock  A.M.  the  weather  was  warm  and  showery. 
The  showers  were  gentle  but  subcontinuous,  with  light-intervals 
between;  i.e.,  during  two  or  three  brief  intervals  the  sunlight  actually 
came  through  the  fog  and  clouds  rather  clearly. 

Two  full-grown  female  specimens  of  M .  subnigrescens,  very  much 
alike,  were  found  depositing  eggs  naturally  on  grass  etc.  in  an  experi- 
ment field.  As  each  nema  still  contained  a  good  many  eggs,  both 
were  taken  to  the  laboratory  in  cold  tap-water,  and  both  subjected  to 
radiant  heat  of  low  frequency,  emanating  from  hot  steel.  The  results 
of  three  trials  on  one  of  the  nemas  and  four  on  the  other  were  quite 
consistent. 

An  ordinary  steel  file  about  nine  inches  long  and  three-fourths  of  an 
inch  wide  was  heated  until  hot,  though  not  red.  As  near  as  could  be 
judged  the  temperature  of  the  file  during  the  trials  was  from  400°-500° 
C.  The  hot  steel  was  held  within  an  inch  and  a  half  to  two  inches  of 
the  nemas.  Held  at  this  distance  from  one's  cheek,  it  caused  an 
agreeable  warm  sensation; — no  disagreeable  sensation  of  heat,  how- 
ever/— no  suggestion  of  scorching. 

When  the  nemas  were  brought  into  the  laboratory,  both  were  still 
slowly  depositing  eggs;  one,  however,  very  slowly, — putting  out  only 
one  or  two  eggs  semi-occasionally.  When  one  of  these  ten-centimeter 
nemas  in  this  laboring  condition  was  removed  from  water  and  stretched 
out  on  a  broad-leaf  plantain,  Plantago  major,  and  the  hot  file  brought 
near,  she  immediately  responded  by  increased  rapidity  of  movement, 
and  in  from  ten  to  twenty  seconds  became  coiled,  sometimes  rather 
closely,  so  that  the  entire  space  occupied  by  her  would  not  be  over 
fifteen  to  twenty  millimeters  across.  Barely  enough  water  was  used 
on  the  plantain  leaf  so  that  only  at  her  points  of  contact  with  the  leaf 
was  she  in  contact  also  with  water.  Doubtless  the  warmth  may  have 
caused  the  water  to  evaporate  a  trifle  more  rapidly,  notwithstanding 
the  saturated  condition  of  the  atmosphere,  and  one  cannot  say  that 
this  change  in  rate  of  evaporation  may  not  have  had  some  effect  on-  the 
behavior,  but  the  inevitable  inference  is  that  the  "radiant  heat"  caused 
the  change  in  behavior,  corroborating,  in  a  reverse  way,  experiments  of 
previous  years  with  direct  sunlight  and  sunlight  passed  through 
heat-diminishing  screens  (both  green  glass  and  living  foliage). 


408  EFFECT  OF  INFRA  RED 

After  the  nemas  had  been  rayed  and  returned  to  water  in  a  watch- 
glass,  and  after  they  had  resumed  their  former  less  active  somewhat 
outstretched  state,  they  were  tested  again  and  again  with  the  infra- 
red rays.  Two  observers,  noting  the  nemas  before  they  were  removed 
from  the  watchglass  of  water  and  after  they  had  been  rayed,  declared  the 
ovijection  to  be  stimulated,  and  in  one  case  the  stimulation  to  be  very 
marked  indeed.  In  this  case,  at  the  time  when  the  nema  was  removed 
from  the  glass,  oviposition  was  diminishing  to  almost  nil,  only  now  and 
then  an  egg  being  deposited, — at  intervals  of  half  a  minute  or  there- 
abouts; however,  after  she  had  been  rayed  and  returned  to  the  water 
where  her  behavior  could  be  observed  more  accurately,  deposition 
was  going  on  vigorously, — batches  of  something  like  twenty  eggs  were 
being  ejected  at  intervals  of  five  to  ten  seconds.  It  should  be  re- 
membered that  these  two  females  already  had  their  egg-laying  capacity 
partially  exhausted  and  were  therefore  probably  less  favorable  speci- 
mens for  experiment  than  if  they  had  just  issued  from  the  ground. 

The  conclusions  drawn  from  the  experiments  were  that,  without 
doubt,  the  radiant  heat  from  the  hot  steel  met  with  instant  response  by  the 
nema  and  that  the  response  was  very  definite  and  that  the  egg  deposition 
was  very  markedly  stimulated  by  the  rays.* 

Apart  from  ultra-violet,  apparently  very  little  is  known  about  the 
relative  amounts  of  various  light  frequencies  that  are  passed  through 
different  quantities  of  fog  and  watery  vapor  in  the  atmosphere.  It  is 
known  that  fog  and  vapor  are  more  or  less  impervious  to  ultra-violet, 
but  pervious  to  many  other  frequencies,  among  them  blue  and  a  cer- 
tain amount  of  red  and  infra-red.  However,  nobody  appears  to  have 
devised  a  method  or  instrument  by  which  the  amount  of  any  particular 
one  of  these  various  other  frequencies  penetrating  under  various  atmos- 
pheric conditions  can  be  satisfactorily  measured,  although  there  is 
reason  to  hope  that  such  data  can  be  established. 

It  is  very  evident,  however,  that  during  the  morning  under  con- 
sideration, which  was  showery  with  light  rain  much  of  the  time,  the 
weather  varying  all  the  way  from  thick  fog  to  almost  sunny, — fog  so 
thick  that  the  fog-horns  were  blowing,  and  yet  at  times  the  sky  toward 
the  east  such  that  the  sunlight  came  through  rather  clearly , — it  is 
very  evident  that  the  amount  of  any  given  spectrum  frequency  reach- 
ing the  experiment  field  probably  would  vary  during  the  morning 
nearly  through  the  entire  daylight  scale,  or  at  least  much  of  it. 

*  But  whatever  stimulus,  if  any,  the  nema  received  from  the  sky  was  not  sufficient 
by  itself  to  cause  any  marked  oviposition. 


EGG  LAYING  OF  M.  SUBNIGRESCENS  409 

APPLICATION  TO  THE  oviJECTiON  OF  Mermis  subnigrescens. 

The  observations  to  date  seem  to  shut  out  the  possibility  that  ultra- 
violet has  much  of  anything  to  do  with  ovijection  taking  place  natu- 
rally in  the  open.  The  present  observations  seem  again  to  make  it 
exceedingly  probable  that  radiant  heat  must  have  much  to  do  with  it. 
Recalling  that  the  early  morning  light  is  relatively  rich  in  red  and 
infra-red,  and  that  as  moisture  (dew,  rain)  is  essential,  or  at  any  rate 
highly  favorable,  to  the  oviposition  of  M.  subnigrescens,  then  obviously 
early  morning  and  forenoon  would  be  a  favorable  time  of  day  for  the 
oviposition.  It  is  certain,  from  spectroscopic  tests  made  during  the 
morning  in  question,  that  all  the  time  after  sunrise  a  good  deal  of  blue 
light  was  being  passed  through  the  atmosphere;  and  it  therefore  might 
have  been  a  behavior  stimulus,  and  no  doubt  was  so. 

All  this  harmonizes  with  previous  experiments  on  the  ovijection  of 
this  species, — an  account  of  which  is  already  published, —  and  explains 
the  motive  for  the  tests  described  above. 

Thus  we  have  a  fairly  complete  theory  of  the  above-ground  egg- 
laying  activities  of  Mermis  subnigrescens.  When  the  nema  is  ripe  for 
labor,  she  moves  from  her  pitch  dark,  subterranean  "domicile"  to  the 
surface  of  the  ground.  Her  movements  during  this  trip  no  doubt 
exemplify  apogeo-,  hydro-,  thermo-,  rheo-,  thigmo-,  and  finally,  just 
before  she  reaches  the  surface,  photo-tropism. 

Once  her  head  is  free  of  the  surface  of  the  ground,  her  chromatrope 
comes  into  full  play,  "detecting"  the  direction  and  amount  of  light 
from  the  sky,  particularly,  perhaps  only,  blue  light.  The  structure  of 
the  chromatrope  is  particularly  adapted  to  the  reception  of  light 
from  above  or  from  any  side,  for  the  light  will  be  concentrated  in  the 
chromatrope  by  the  transparent  front  tissues  of  the  head  acting  as  a 
hemispherical  lens,  and  the  side  tissues  acting  as  a  cylindrical  lens. 

As  she  clambers  higher  and  higher  on  the  herbage,  she  responds  to 
such  blue  sky  light  as  is  not  intercepted  by  the  green  blades  of  grass 
and  other  foliage  above  and  around  her.  Led  by  the  blue  light  and 
the  urge  to  deposit,  she  will  at  last  reach  an  elevation  on  the  herbage 
subject  to  a  more  direct  action  of  the  sun's  rays,  when  the  ovijector 
and  uterine  muscles  will  be  affected  by  "red"  rays  and  ovijection  will 
begin;  and  this  place  in  many  instances  would  be  at  the  altitude  of 
grazing  grasshoppers,  the  definitive  hosts. 

This  would  be  a  new  and  special  parallel  to  the  ordinary  sequence  of 
events  in  ovijection  and  parturition.  In  other  words  the  "voluntary" 
nervous  system  comes  first  into  play,  bringing  the  organism  into  con- 


410  EVIDENCE  FOR  CHROMATROPISM 

ditions  favorable  to  the  events  about  to  follow.  Thereafter  the  be- 
havior is  more  or  less  "involuntary,"  as  has  been  shown  in  the  present 
instance  by  the  fact  that  ovijection  continues  under  the  stimulus  of 
sunlight,  even  if  the  head,  including  the  chromatrope  and  central 
nervous  system,  be  removed, — seared  off. 

CIRCUMSTANTIAL  EVIDENCE   FOR   THE    CHROMATROPISM   OF 

Mermis  subnigrescens 

1.  The  commonly  infested  grasshoppers  graze  mostly  within  certain 
limits  above  the  ground;  harmoniously,  the  eggs  of  the  mermithid 
parasite  are  found  to  occur  preponderantly  within  these  limits,  sug- 
gesting highly  developed  egg-laying  instincts  on  the  part  of  the  nema 
that  might  well  presuppose  tropism. 

2.  A  definite  mechanism,  believably  a  phototrope  [includes  chroma- 
trope,  (includes  glaucotrope)]  embodying  what  are  believably  recep- 
tors, transmitters,  and  effectors,  is  present; — a  mechanism  not  other- 
wise readily  explicable.    The  only  mermithid  individuals  known  to 
possess  such  a  mechanism  fully  developed  are  those  whose  blackish 
eggs  are  deposited  in  the  way  characteristic  of  Mermis  subnigrescens. 

3.  The   putatively-chromatropic   pigment   absorbs, — i.e.,    can   be 
sensitive  to, — blue  rays. 

4.  Only  adult,  chromatroped,  egg-laying  females  clamber  as  de- 
scribed.   Males  and  young  females  having  no  power,  or  occasion, 
to  deposit  eggs  are  not  chromatroped. 

5.  The  clambering  of  the  nemas  ripe  for  oviposition  is  skyward; — 
i.e.,  toward  blue  sky,  rather  than  vertical  (distinction  from  negative 
geotropism).    Beams  of  blue  light  from  the  sky,  often  oblique,  and 
coming  from  many  widely  different  directions,  are  those  most  certain 
promiscuously  to  penetrate  the  depths  of  the  herbage,  and  thus  reach 
to  near  the  ground.    The  nema's  lens-like  tissues  concentrating  light 
upon  the  chromatrope,  accept  it  from  above  and  from  all  sides;  this 
harmonizes  with  the  distribution  of  blue  sky  light. 

6.  Oviposition  is  stopped,  or  very  much  slowed,  by  green  screens 
(including  living  foliage)  that  absorb  red  and  infra-red;  indicating  a 
necessity  for  the  nema  to  escape  from  exclusively  green  light  before 
oviposition  can  take  place.    In  the  grasshopper  habitats,  blue  light 
(sky-light)  is  the  most  diffused  and  most  likely  to  be  useful  in  leading 
to  the  known  consummation,  should  chromatropism  come  into  play 
at  all.     In  nature,  clambering  skyward  ('"blue-ward")  from  out  the 
green,  brings  the  nema  soonest  under  the  incidence  of  the  longer  wave 
lengths  so  stimulative  to  the  ovijectors. 


INITIAL  STRATIGRAPHIC  SURVEY  OF  NEMAS 

In  the  upper  20  mm.  of 

MARINE  BEACH  SAND,  NEAR  LOW  TIDE  MARK » 

CONTRIBUTIONS  TO  A  SCIENCE  OP  NEMATOLOQY  XXI 
BY  N.  A.  COBB 

In  1916  studies  at  the  laboratory  of  the  Bureau  of  Fisheries,  Woods 
Hole,  Massachusetts,  showed  that  sandy  beaches,  far  from  being 
utterly  barren,  carry  a  comparatively  rich  fauna  of  microscopic  organ- 
isms. What  biological  and  economic  role  these  organisms  may  play  is 
little  known.  Conceivably  they  may  be  more  important  than  would 
at  first  be  suspected.  Recall  that  many  larger  aquatic  organisms, 
at  one  period  or  another,  may  pass  a  certain  amount  of  time  on  the 
bottom.  During  this  sojourn  their  relationship  to  the  microscopic 
inhabitants  of  the  sand,  mud,  etc.  constituting  the  bottom,  is  a  matter 
about  which  we  know  very  little,  but  it  is  easy  to  imagine  that  some- 
times the  relationship  may  be  important.  Again,  the  sand-  and  mud- 
inhabiting  organisms  themselves  may  be  temporary  stages  (eggs, 
larvae)  in  a  varied  life  history. 

Such  thoughts  led  to  a  stratigraphic  examination  of  marine  beach 
sand  at  Woods  Hole,  August,  1928.  A  small  sheet-metal  box,  10 
centimeters  square,  carrying  a  series  of  thin  metal  slides  was  devised, 
such  that  by  its  aid  layers  of  sand  5  mm.  thick,  lying  one  above  another 
in  series,  could  be  collected  (Figs.  1  and  2).  In  each  of  two  collec- 
tions four  such  successive  horizontal  layers  were  examined  for  their 
nemas.  The  results  are  indicated  in  the  following  tables : 

Collection  I:  Layer  No.  I      topmost  1st  5mm.  100  sq.  cm.         905  nemas 

"        «    II  2nd       "  "       "  1,355      " 

"        «     HI  3rd        "  "       "  1,009      " 

"    IV  4th        "  175      " 

Collection  II:    Layer  No.  I      topmost  1st   5  mm.  100  sq.  cm.       1,512  nemas 

"     II  2nd        "  1,403       " 

«     HI  3rd         "  "       "                981       " 

«    IV  4th        "  226      " 

Only  two  collections  were  made,  as  the  census  is  a  very  tedious  one. 
It  will  be  seen  that  the  two  collections,  taken  a  few  yards  apart,  give 

Reprinted  from  the  JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES,  Vol.  19, 
No.  10,  May  19,  1929. 


412 


STRATIGRAPHIC  APPARATUS 


rather  consistent  stratigraphic  numbers;  so  that  we  may  say,  as  a  result 
of  these  two  examinations,  that  probably  the  number  of  nemas  in  each 
successive  layer  decreases,  rather  gradually  at  first,  but  rapidly  below 
the  third  5  mm.  layer;  i.e.,  to  a  depth  of  about  15  mm.  the  sand  is 
thickly  populated  with  nemas;  below  that  level  the  number  falls  off 
rapidly.  The  deeper  layers  contain  fewer  nemas,  and  fewer  species. 


Fig.  1.  See  also  Fig.  2.  Apparatus  for  collecting  layers  of  sand  and  mud  on  beaches, 
mud  flats,  and  at  the  bottom  of  ponds,  lakes  and  seas.  The  unassembled  apparatus  is 
shown  at  the  left;  its  use  in  collecting  is  explained  in  the  successive  illustrations  in  Figs. 
1  and  2,  reading  from  left  to  right.  All  the  operations  except  the  last  must  be  performed 
at  the  time  of  collecting.  The  last  operation  may  take  place  in  the  laboratory.  The 
rectangular  collecting  box,  with  two  sides  missing,  is  forced  into  the  sand  or  mud.  The 
two  missing  sides  (gate  and  loose  bottom)  are  then  inserted,  as  shown  above.  To  insert 
the  loose  bottom  the  adjacent  sand  is  pawed  away. 


Fig.  2.  See  also  Fig.  1.  After  the  sample  of  sand  is  removed  from  the  bottom,  it  is 
placed  in  a  holder  having  three  thin  metal  slides  (1,  2,  3),  that  can  be  forced  through  the 
sand  parallel  to  each  other,  thus  cutting  it  into  four  layers; — in  this  case  each  layer  is 
5  mm.  thick.  After  the  slides  are  forced  home,  as  shown  at  the  right,  the  loose  bottom  of 
the  box  is  removed,  disclosing  the  lowest  layer  of  sand, — 5  mm.  thick.  This  is  washed 
into  a  beaker  and  treated  as  desired.  The  top  of  the  box  has  fine  perforations  in  order  to 
allow  the  supernatant  water  to  escape  without  disturbing  the  top  layer  of  sand  or  mud. 
To  prevent  the  possible  escape  of  small  organisms,  this  perforated  top  may  be  further 
covered  with  the  finest  bolting  silk,  stretched  on. 

Averaging  the  figures  from  the  two  collections  mentioned  above, 
it  will  be  seen  that,  if  they  are  typical  collections,  the  beach  sand 
examined  carried  about  3,742,000,000  nemas  per  hectare  in  the  top 
20  mm.,  or  about  1,500,000,000  per  acre.  In  1916,  but  earlier  in  the 
summer,  an  examination  of  the  same  beach  showed  at  least  1,040,000,- 
000  per  acre  in  the  topmost  inch  of  sand. 


THE  AMBULATORY  TUBES  AND  OTHER  FEATURES 

of  the  ncma 

DRACONEMA  CEPHALATUM 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XXII1 
BY  N.  A.  COBB 

There  is  no  adequate  published  description  of  the  locomotion  of 
Draconema  and  its  numerous  marine  relatives ;  very  few  persons  have 
ever  witnessed  one  of  these  nemas  perambulating  its  natural  sub- 
stratum. 

Draconema  moves  much  after  the  manner  of  the  ordinary  inchworm, 
or  measuring  worm.  The  caterpillar  called  the  "inchworm"  has  two 
bunches  of  feet,  a  bunch  near  each  extremity.  Standing  on  the  bunch 
of  hind  feet,  it  stretches  forward  and  takes  hold  with  the  front  bunch. 
Then,  releasing  the  hind  bunch,  it  draws  the  body  forward  into  a  loop 
so  that  the  posterior  bunch  may  attach  itself  near  the  front  one. 
Loosening  the  front  bunch,  the  caterpillar  again  stretches  forward, 
etc. 

It  is  convenient  to  speak  of  the  two  attachment  organs  of  the  adult 
Draconema  as  "soles."  The  method  of  attachment  of  these  soles  to 
the  substratum  in  Draconema  is  very  different  from  that  of  the  inch- 
worm.  The  sole  of  Draconema  is  armed  with  projecting  hollow  setae 
connected  with  internal  glands  supplying  a  sticky  and,  presumably, 
non-water-soluble  secretion,  and  it  is  by  the  aid  of  this  secretion 
emerging  from  ends  of  the  hollow  setae  that  the  sole  is  attached. 

Reprinted  from  the  JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES,  Vol.  19, 
No.  12,  June  19,  1929. 


414 


THE  MAIN  SOLE  OF  DRACONEMA 


X200 


Junint 


sfflrac.... 


set  irar 


fh  tst          asrsoa 

Fig.  1.— Male  Dra- 
conema  cephalatum, 
showing  the  two  soles 
armed  with  ambula- 
tory setae.  One  of 
the  setae  is  shown 
below  more  highly 
quirt  magnified,  set  amb. 
The  labial  sole  is  very 
much  the  smaller. 


rnt 


dm 


sir  rm 


sd<jilil6!  s>1  naib 


him  in  A  glance  at  Fig.  1  will  enable  the  reader 
at  once  to  understand  the  posterior  "sole" 
of  Draconema  cephalatum.  It  is  of  con- 
siderable  extent,  occupying  most  of  the 
posterior  fifth  of  the  ventral  surface  of  the 
body,  and  is  characterized  by  very  obvious, 
longitudinal  groups  of  curved  ventrad 
setae. 

The  much  smaller  anterior  sole  is  very 
near  the  front  of  the  head  on  the  dorsal 

millf  side,  and  is  characterized  by  setae,  smaller 
than,  but  similar  to,  those  of  the  other 
sole. 

The  main  sole. — Favorably  stained  speci- 
mens exhibit   the  structure   of   the   am- 

S1  „/„/,  bulatory  adhesion  tubes,  as  well  as  of  the 
associated  multicellular  ventral  glands  ar- 
ranged in  a  long  ventral  group  opposite  to 
and  a  little  in  front  of  the  major  sole. 
Each  adhesion  tube  connects,  at  its  base, 
with  a  duct  that  leads  to  a  separate  gland. 
The  anterior  pair  may  be  taken  as  typical 
of  any  group-member  of  this  compact 
f  composite  series  of  glands  (see  Figs.  1  and 
;  2) .  This  anterior  pair  is  sometimes  more 
distinctly  separated  from  the  general  mass 
of  the  glands  than  are  any  of  the  subsequent 


THE  MINOR  OR  CEPHALIC  SOLE 


415 


pairs  or  groups ;  and  each  of  these  two  glands  proves  to  have  three  nuclei. 
(See  Fig.  2.)  The  cells  of  each  gland,  as  well  as  their  spheroidal 
nuclei,  increase  in  size  from  front  to  back,  the  anterior,  i.e.,  distal, 
cell  having  less  than  one-eighth  the  volume  of  the  posterior;  the 
nucleus  in  the  small  anterior  cell  is  also  less  conspicuous.  This  group 
(pair)  of  glands  is  more  or  less  clavate  in  form  and  is  nearly  as  long  as 
the  corresponding  body  diameter.  Posteriorly,  each  gland  diminishes 
suddenly  in  diameter  to  form  a  duct  about  half  as  wide  as  one  of  the 
adjacent  annules  of  the  cuticle.  Near  the  gland  the  wall  of  the  duct 
contains  somewhat  elongated  nuclei  of  considerably  smaller  size  than 
the  nuclei  of  the  glands.  The  duct  also  lacks  the 
granular  character  of  the  glandular  cells  themselves. 
The  two  ducts,  at  first  ventral,  diverge  backward 
to  the  two  foremost  adhesion  tubes,  and  are  one  to 
two  times  as  long  as  the  glands.  Near  where  a  duct 
enters  the  somewhat  swollen  base  of  an  adhesion 
tube,  there  is  a  small  duplex  enlargement  or  ampulla. 
In  the  specimens  under  examination,  only  in  the  very 
basal  portion  of  the  adhesion  tube  is  there  any 
indication  of  the  staining  action  of  the  acid  carmine. 

The  numerous  glands  composing  this  ventral 
series  are  so  closely  packed  together  that,  as  a  rule, 
it  is  difficult  to  distinguish  the  exact  number  of 
groups,  but  it  is  evident  that  throughout  the  series 
the  glands  are  arranged  in  groups  side  by  side, 
apparently  mostly  in  pairs  or  quartets,  the  number 
of  glands  being  commensurate  with  the  number  of 
adhesion  tubes.  On  occasions  when  the  entire 
group  of  glands  is  slightly  separated  from  the  body 
wall,  and  therefore  from  the  bases  of  the  adhesion 
tubes,  the  ducts  leading  to  the  tubes  are  distinctly 
visible,  and  have  the  appearance,  when  viewed 
laterally,  of  a  rather  complicated  plexus. 

The  minor,  or  cephalic,  sole. — The  dozen  or  so 
adhesion  tubes  and  glands  of  the  cephalic  sole  have 
the  same  general  plan  as  the  sublateral  and  sub- 
ventral  ones  of  the  posterior  sole  just  described. 
The  glands  connected  with  the  cephalic  tubes 
(gl.  pint)  are  located  mainly  dorsad  in  the  anterior  two-fifths  of  the 
neck  between  the  oesophagus  and  the  body-wall;  there  are  two  dorsally 


mi!, 


Fig.  2.— Anterior 
ambulatory  seta  of 
D.  cephalatumvrith 
its  3-celled  gland, 
its  3-celled  mate 
concealed,  though 
part  of  its  duct 
shows, — del  snst.; 
som,  body  wall;  cl 
msc,  somatic  mus- 
cle; an  cut,  cuticu- 
lar  annules;  mur 
ext  and  rwwr  int, 
outer  and  inner 
walls  of  ambula- 
tory tube;  os  tb, 
secretory  pore. 


416  THE  AMBULATORY  TUBES 

sublateral  groups  of  glandular  cells  and  four  subdorsal  groups,  cor- 
responding to  a  similar  grouping  of  the  six  pairs  of  adhesion  tubes. 
The  glands  of  the  cephalic  sole  are  sometimes  rather  more  strongly 
stained  than  those  of  the  posterior  sole  in  the  same  specimen,  but 
present  the  same  general  anatomical  and  histological  structure. 
Referring  to  the  dorsally  sublateral  cervical  glands  as  examples  (see 
Fig.  1),  these  are  distinctly  granular  in  structure  and  apparently 
duplex,  that  is,  have  a  well  marked  constriction  near  the  middle,  on 
opposite  sides  of  which,  fore  and  aft,  is  a  considerable  volume  of 
nuclear  (?)  matter;  the  remaining  portion  of  the  cells  is  rather  coarsely 
granular,  the  granules  measuring  nearly  l/j.  in  diameter.  This  duplex 
glandular  mass  is  hah"  as  long  as  the  neck  and  anteriorly  tapers  to  a 
tubular  portion  not  much  wider  than  one  of  the  cervical  annules. 
This  narrow  portion  of  the  gland  in  turn  tapers  to  a  very  narrow  duct 
about  2ju  in  diameter,  which  swells  to  form  a  fusiform  duplex  ampulla 
as  wide  as  one  of  the  coarser  cervical  annules.  The  ampulla  empties 
forward  through  a  short  narrow  duct,  1  to  2  /j.  wide,  directly  into  the 
base  of  the  corresponding  adhesion  tube,  where  a  little  stained  matter 
may  usually  be  seen.  The  adhesion  tubes  reach  exactly  to  the  lips, 
so  that  their  outpour  is  practically  terminal.  All  these  details  are 
shown  on  a  small  scale  in  Fig.  1, — ampullae  reduced  to  two  dots. 

The  distal  extremity  of  the  ambulatory  tube  is  somewhat  bell- 
shaped,  and  the  lumen  of  the  tube  is  prolonged  into  the  cavity  of  the 
bell  through  a  short  conoid  extension.  The  significance  of  this  bell- 
shaped  structure  remains  more  or  less  problematical.  No  elements 
have  been  seen  in  the  tube,  or  hi  the  bell,  that  could  be  regarded  as 
contractile,  and  one  therefore  seems  obliged  to  assume  that  whatever 
changes  of  form  are  exhibited  by  this  bell-shaped  structure  are  due  to 
such  factors  as  its  own  elasticity,  the  pressure  of  the  internal  secretion 
and  counter  pressure  of  the  external  water.  It  would  seem  advan- 
tageous to  the  nema  if  the  secretion  which  flows  out  through  the  bell- 
shaped  organ  could  be  "cut  off"  at  will,  and  it  is  conceivable  that  this 
bell-shaped  affair  in  some  way  accomplishes  that  end.  Again,  it  is 
conceivable  that  the  bell  may  mechanically  give  to  the  end  of  the  tube 
a  greater  adhesiveness,  conceivably  through  suction, — a  suction  that 
might  be  made  to  vary  with  the  relationship  of  the  distal  end  of  the 
tube  to  the  substratum,  as  in  the  familiar  elastic  concave  rubber 
suction  disc. 

The  facts  that  the  setae  of  the  inner  rows  are  always  the  shorter, 
and  that  all  the  setae  are  incurved,  suggest  that  a  suitable  substratum 
may  be  a  microscopic  filament,  or  a  thin  edge  of  something.  This 


INTERNAL  ANATOMY  417 

thought  arises  from  the  fact  that  the  main  sole  appears  "bow-legged," 
as  it  were.  Such  apparently  suitable  thin  and  narrow  forms  of  sub- 
stratum occur  on  certain  marine  algae  and,  as  a  matter  of  fact,  at 
least  two  observers — Cobb  and  Chambers — have  seen  Draconema  per- 
ambulating the  surface  of  algae. 

In  balsam  specimens  from  Hudson  Bay  the  body-wall  tissues  sur- 
rounding the  mouth-opening  have  a  golden  yellow  color  and  take  on  the 
form  of  a  six-parted,  but  twelve-pointed,  star. 

Probably  the  excretory  pore  is  at  the  lips.  I  formerly  referred  to  a 
cell  just  behind  the  cardia  as  possibly  representing  the  renette;  this 
suggestion  may  not  be  well  founded.  In  this  region  I  observe  two  of 
these  cells  lying  side  by  side  in  sub  ventral  position  (see  Fig.  1),  sepa- 
rated by  a  small  space.  In  the  same  latitude,  just  behind  the  minute 
cardiac  cavity,  on  each  side  of  the  intestine,  there  is  a  rather  compact 
group  of  granular  cells  containing  about  a  dozen  nuclei.  These  groups 
are  as  long  as  the  corresponding  body  diameter,  and  about  half  as  wide 
as  long.  Between  the  two  groups,  on  the  dorsal  side,  there  is  a  pair  of 
subdorsal  granular  cells  rather  closely  resembling  the  subventral  ones 
just  described.  As  to  the  function  of  these  lateral  groups  of  cells,  it 
seems  not  impossible, — as  they  are  free  at  their  posterior  ends  and  seem 
connected  with  the  intestine  anteriorly, — that  they  may  be  special 
glands  associated  with  digestion.  There  is  a  similar  pair  of  lateral 
groups  of  cells  in  front  of  the  cardia,  emptying  (?)  backward.  I  do 
not  think  the  possibility  is  excluded  that  some  of  these  cells  are  nerve 
cells. 

The  intestine  is  composed  of  cells  of  such  a  size  that  about  six  are  re- 
quired to  complete  a  circumference.  The  thin  refractive  lining  is  hardly 
1  n  thick.  The  cardia,  as  usual,  presents  a  distinct  group  of  closely 
packed  nuclei,  indicating  that  it  is  composed  of  cells  of  rather  small 
size,  of  which  the  number  is  probably  about  fifteen  to  twenty.  Notable 
is  the  presence  of  scattered  cells  in  the  wall  of  the  intestine  which  stain 
differently  from  their  neighbors.  These,  no  doubt,  discharge  some 
special  function.  Thus  far  they  have  been  observed  only  in  the  an- 
terior portion  of  the  intestine. 

The  portion  of  the  neck  opposite,  and  adjacent  to,  the  oesophageal 
constriction,  except  such  portion  as  is  occupied  by  the  glands  of  the 
minor  sole,  is  rather  closely  packed  with  nerve  cells. 

The  lateral  fields  are  one-third  as  wide  as  the  body  and  contain 
a  considerable  number  of  nuclei  rather  irregularly  arranged. 

The  cuticle  in  the  posterior  region  of  the  tail  is  traversed  by  ra- 
dial elements  that  give  rise  to  a  finely  punctate  appearance  on 
the  surface  (see  Fig.  1). 


418  GONADS.      NOMENCLATURE 

An  interesting  observation  is  the  apparent  connection  of  the  tandem 
group  of  three  caudal  glands  with  the  dorsal  field  by  means  of  a  narrow 
strand  running  forward,  possibly  of  a  nervous  character,  as  is  sug- 
gested: 1,  by  its  form  and  position;  2,  by  its  size  and  structure. 

The  internal  extremity  of  the  gubernaculum  lies  near  the  body  axis 
and  is  connected  fore  and  aft  with  the  ventral  body-wall  by  slender 
strands  of  muscular  tissue.  The  testis  is  now  believed  to  be  reflexed, 
not  outstretched  as  formerly  figured. 

The  broad,  rapidly  tapering  ovaries, — the  anterior  lying  to  the  right, 
the  posterior  to  the  left, — are  reflexed  to  nearly  opposite  the  vulva  and 
contain  comparatively  few  ova,  arranged  in  single  file  in  the  wider 
part,  elsewhere  irregularly.  Hundreds  of  subspherical  sperm  cells 
may  occur  in  the  uterus.  Usually  there  is  one  egg  at  a  time  in  the 
uterus,  thin  shelled  and  smooth,  and  deposited  before  segmentation 
begins.  The  eggs  are  three-fourths  as  wide  as  long  and  about  two- 
thirds  as  long  as  the  corresponding  body  diameter. 

Some  of  the  results  of  the  present  investigation  have  been  more  or 
less  definitely  forecast  by  various  observers  on  several  occasions, 
notably  by  Steiner  and  Irwin-Smith,  both  of  whom  from  inadequate 
material,  have,  with  admirable  insight,  suggested  the  probable  con- 
nection of  the  adhesion  tubes  with  internal  structures  and  also  the 
possibility  of  the  glandular  nature  of  these  latter. 

While  no  doubt  now  remains  that  both  the  major  and  minor  soles 
are  glandular  and  are  organs  of  locomotion,  it  still  seems  to  me  quite 
doubtful  whether  we  fully  understand  the  bodily  structure  of  Dra- 
conema. The  form  of  the  head  and  neck  and  other  parts  do  not  seem 
to  be  explained  merely  on  the  basis  of  the  use  of  these  two  "sticky" 
soles  in  locomotion.  There  probably  are  other  unknown  factors  play- 
ing a  part  in  the  activities  of  Draconema  that  will  further  explain  its 
highly  peculiar  and  interesting  structure.2 

J  Nomenclature.  The  proposal  of  the  genus  Draconema  in  1913  appears  reasonable 
in  view  of  the  fact  that  at  that  time  the  published  descriptions  of  the  species  belonging 
to  its  family,  though  in  no  case  as  complete  as  desirable,  indicated  the  existence  of  two 
(or  more)  genera,  the  type  species  of  one  of  which  should  be  that  originally  named  by 
Claparede  Chaetosoma  ophiocephalum  1863  (not  Chaetosoma  Westwood,  1851,  Cole- 
optera).  Draconema  cephalatum,  was  then,  and  continues  to  be,  thought  generically 
different  from  Claparede's  ophiocephalum.  The  name  Chaetosoma,  being  preempted, 
should  be  replaced  by  its  synonym  Notochaetosoma  Irwin-Smith  1917.  Should  the  opin- 
ion prevail  that  all  the  described  forms  of  the  family  belong  to  one  genus,  then  the 
oldest  synonym  for  Chaetosoma  would  be  Draconema,  and  should  be  substituted.  In 
that  event,  the  family  name  would  naturally  become  Draconematidae;  in  any  case,  it 
seems  likely  that  Draconema  is  a  better  representative  of  the  group  than  the  only  other 
genus  so  far  proposed,  Notochaetosoma. 

Draconema  cephalatum  is  cosmopolitan,  and  seems  to  have  been  described  by  several 
different  authors  under  as  many  different  specific  names,  e.g.,  annulatum  Ditlev., 
haswelli  Irwin-Smith.  hibemicum  Southern. 


OBSERVATIONS  ON  THE  MORPHOLOGY 
AND  PHYSIOLOGY  OF  NEMAS 

Including  notes  on  new  species 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XXIII 
BY  N.  A.  COBB 

1.    A   NEW   SUBGENTJS   OF  RHABDITIS 

There  is  a  group  of  slender-tailed  amphigonic  rhabdites  having 
lips  and  pharynx  as  shown  in  Fig.  1,  the  males  of  which  have  weakly 
developed  bursas.  Such  rhabdites  have  been  described  from  time 
to  time  but  no  author  seems  to  have  had  adequate  material  for  a 
completely  satisfactory  description.  Having  examined  living  speci- 
mens of  both  sexes  of  a  new  species  of  this  group  I  took  the  occa- 
sion to  prepare  a  fuller  description  of  it,  and  propose  it  as  the  type 
of  Rhabditella,  a  new  subgenus  of  the  genus  RhabditJs  Dujardin. 


Rhabditis  (Rhabditella)  leptura  n.  sp  . 


Thin  layers  of  the  transparent,  colorless,  naked  cuticle  are  traversed  by 
excessively  fine,  plain,  transverse  striae,  resolvable  only  with  the  highest 
powers.  Longitudinal  striations,  due  to  the  attachment  of  the  musculature, 
are  visible  in  most  regions  of  the  body.  No  deirids  have  been  observed. 
The  neck  is  very  slightly  conoid.  The  cross  section  of  the  pharynx  is 
roundish-triangular;  yet  the  almost  imperceptibly  sigmoid  pharynx  is  nearly 
equidiametral  throughout,  though  anteriorly  the  walls  are  a  trifle  more 
strongly  refractive.  The  glottis  is  a  trifle  oblique,  but  otherwise  fairly  typical. 
The  oesophagus  presents  a  median,  fairly  prominent,  ellip- 
soidal swelling,  or  bulb,  two-thirds  as  wide  as  the  middle  of  the 
neck,  and  a  somewhat  ellipsoidal,  or  obscurely  pyriform  pos- 
terior bulb  two-thirds  as  wide  as  the  base  of  the  neck,  —  both 
swellings  of  approximately  the  same  diameter.  The  median 
swelling  presents  an  elongated,  obscure  but  rather  large, 
valvular  apparatus,  while  the  cardiac  bulb  presents  a  rather 
strongly  refractive,  somewhat  three-fold,  striated  valvular  ap- 
paratus, located  a  little  in  front  of  the  middle  of  the  bulb.  At 
the  nerve-ring  the  oesophagus  is  one-third,  and  in  front  of  the 
cardiac  bulb  about  one-fourth,  as  wide  as  the  corresponding 
portion  of  the  neck.  There  is  a  distinct  cardiac  collum  con- 
stituting a  rather  broad  constriction,  so  that  the  anterior 
portion  of  the  intestine  through  a  distance  nearly  equal  to  one  .....  _____ 
body-width  enlarges  from  about  one-third  to  five-sixths  as  Fig  L  Front  and 
wide  as  the  body.  This  appearance,  however,  is  somewhat  ^f^^fj^l 
variable.  The  nerve-ring  surrounds  the  oesophagus  obliquely,  hptwa.  Thebegin- 
The  intestine,  the  lining  of  which  is  somewhat  refractive,  is  ^Vlhown  15  Pthe 
made  up  of  cells  of  such  size  that  probably  only  about  two  lower  illustration. 
are  presented  in  each  cross  section;  these  cells  contain  granules 
of  variable  size,  which  are  not  strongly  birefringent.  With  crossed  nicols 
there  is  no  suggestion  of  a  St.  Andrew's  cross;  —  not  at  all  like  the  strong 
birefringence  of  R.  monohystera.  The  posterior  Up  of  the  anus  is  very  slightly 
raised.  The  rectum,  whose  lining  is  only  slightly  refractive,  is  one  and  one- 
Reprinted  from  the  JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES,  Vol.  19, 
No.  13,  July  19,  1929. 


420 


MALE  RHABDITIS  (RHABDITELLA)  LEPTURA 


third  times  as  long  as  the  anal  body  diameter.  The  vulva  is  slightly  de- 
pressed, though  its  lips  are  slightly  elevated.  The  ovaries  extend  two-thirds 
the  distance  back  to  the  vulva,  and  are  only  about  one- 
sixth  as  wide  as  the  body  of  the  female.  The  smooth,  thin- 
shelled,  ellipsoidal  eggs,  about  as  long  as  the  body  is  wide  and 
two-thirds  as  wide  as  long,  have  been  seen  in  the  uteri  one  at  a  // 
time.  Their  yolk  is  made  up  of  closely  packed,  faintly  refrac- 
tive, spherical  granules,  scattered  among  which  are  a  few 
exceedingly  small  granules  less  than  one  micron  in  diameter. 

§ *"?" ""La/ "^4! — "¥.2"VS,3.iL°>61mm  There  are  two,  equal, 
separate  spicula.  The  nema  must  be  tipped  a  little  in  order 
to  bring  the  slightly  developed  obscure  bursa  into  profile  view. 
The  foremost  papilla,  or  bursal  rib,  is  somewhat  variable  in 
position  and  is  sometimes  found  nearly  as  far  forward  as  the 
proximal  ends  of  the  spicula.  Fig.  2. 

The  testis  is  reflexed  at  its  free  end  for  a  distance  equal  to 
about  two  body  diameters.  This  portion  of  the  testis  is  only 
about  one-fourth  as  wide  as  the  body,  though  it  is  very  slightly 
swollen  at  its  extremity.  Behind  the  flexure  for  some  little 
distance  the  testis  still  remains  narrow, — only  a  little  wider 
than  the  reflexed  portion  lying  alongside.  Then,  however, 
it  rather  suddenly  enlarges  and  soon  becomes  half  as  wide  as 
the  body  and  so  continues,  enlarging  slightly,  however,  for 
three  or  four  body  widths.  In  this  portion  of  the  testis  the 
spermatocytes  pass  through  their  growth  period;  they  appear 
as  if  in  two  rows  and  in  pairs  side  by  side,  and  one  gets  the 
impression  that  these  pairs  are  twin  cells.  Their  nuclei  are 
large,  becoming  at  last  half  as  wide  as  the  elongated  sperma- 
tocytes themselves,  i.e.  one-fifth  as  wide  as  the  nema  About 
halfway  from  the  blind  end  of  the  testis  to  the  anus  the  full 
grown  spermatocytes,  here  half  as  wide  as  the  body  and 
about  as  long  as  wide,  apparently  break  successively  into 
quartets,  the  resulting  subspherical  cells  being  a  little  more 
than  one-fourth  as  wide  as  the  body.  For  a  distance  equal 
to  about  two  body  diameters  forward  from  the  spicula  the 
sexual  organ  is  narrower, — about  one-third  as  wide  as  the 
body.  Whether  the  cells  of  the  quartet  divide  further  remains 
unknown. 

Examination  of  one  of  the  members  of  a  quartet  indicated 
the  probable  presence  of  about  seven  chromosomes. 

Habitat:  Decaying  fruit  of  luffa  acutangula  from  Tela, 
Honduras,  October,  1926.  Sent  by  Horace  S.  Dean. 

Diagnosis:  Rhabditella  subg.  nov.     Rhabdites  having  lips 
and  pharynx  as  shown  in  Fig.  1,  the  males  of  which  have* 
weakly  developed  costate  bursa  and  long  slender  tails. 

Diagnosis:  Rhabditis  (Rhabditella)  leptura  n.  sp.  Rhab- 
ditellas  dimensioned  as  shown  in  the  formulae;  male  with 
two  separate  spicula,  a  simple  inconspicuous  gubernacu- 
lum,  and  with  nine  bursal  ribs  arranged  as  shown  in  Fig. 
2;  phasmids  present. 


'In 


p/i.w 


Urn 


X750 


OXYURIDS  OF  MILLIPEDS 


421 


int. 


2.  MYOLABIA  ON  A  NEMIC  PARASITE  OF  MILLIPEDS 

The  front  view  of  the  lip  region  of  Thelastoma  attenuatum  Leidy,  a  nema 
from  the  intestine  of  the  milliped  Sporobolus  marginatus,  gives  the  impression 
at  first  that  there  is  a  circlet  of  10  "lobes"  surrounding  the  usual  three 
lips.    Careful  scrutiny  shows  that  two  of  these  ten 
lobes,    the   lateral   ones,    are   the   external   amphids. 
This  leaves  8  other  lobes  arranged  in  4  submedian 
pairs. 

A  similar  condition  exists  on  another,  and  new, 
species  of  Thelastoma  occurring  in  the  same  host,  ex- 
cept that  in  this  new  nema  the  amphidial  lobes  do  not 
so  closely  resemble  the  other  8.  Fig.  3.  In  the  new 
species  the  first  slice  behind  the  lip 
region  discloses  the  anterior  parts  of  8 
muscular  fields  that  extend  throughout 
the  body,  as  may  be  shown  by  cross 
sectioning.  Fig.  3.  Furthermore,  it  is 
quite  evident  that  the  8  labial  "lobes" 
are  the  external  cephalic  expression  of 
these  8  longitudinal  muscular  fields. 

It  is  therefore  very  interesting  to  find 
that  in  a  second  new  species  of  Thelas- 
toma, belonging  to  a  new  subgenus  and 
infesting  a  different  host  (namely  the 
milliped  Fontaria  marginata  Say,  as 
found  in  Virginia,  U.  S.  A.,  near  the  "  X175 

District  of  Columbia)  the  8  organs  which  g^  4andFl^S  °ff 
in  Thelastoma  attenuatum  are  rather  in-  Tkeiasiom 
conspicuous  lobes  surrounding  the  true 
lips,    have    entirely    displaced   the  f.i.f / 
ordinary  lips,  forming  a  lip  region     ' 
prominently  set  off  by  constric- 
tion, and  consisting  of  8  prominent 
subequal  contiguous  parts  folded 
completely  together  over  the  phar- 
t  ynx  and  constituting  lips  of  a  new 

Fig.  3.      Measurements,  front    »  ° — r-     — 

view  of  the  lip  region  and  near-   SOrt. 
by  cross-sections  of  Thelastoma 
(Thelastoma}  spicatum  n.  sp. 


Figs.  4  &  5.     This 

F resents,  in  cross-section, 
muscular  fields.  Fig.  5. 

These  lips  may  be  called  pseudolabia; — or,  because  of 
their  connection  with  the  longitudinal  muscular  fields  of 
the  nema,  myolabia.  No  cephalic  papillae  have  as  yet 
been  seen  on  these  myolabia. 

Diagnosis.  Thelastoma  (Thelastoma)  spicatum  n.  sp. 
Much  like  T.  attenuatum  Leidy,  but  smaller  and  with 
shorter  spicate  tail  and  more  completely  differentiated, 
though  still  rather  vague,  myolabia.  Dimensioned  as 
shown  in  the  formula.  Fig.  3.  Attenuatum  and 
spicatum  may  occur  together  in  the  intestine  of  the  mil- 
liped, Sporobolus  marginatus. 

Diagnosis.  Thelastomellum  subg.  nov.  Thelastomas 
with  8  well-developed  myolabia  as  in  Fig.  5.  Type 
species  T.  myolabiatum  n.  sp. 


myoiabiatum  spec. 


422 


SYNGONY  IN  OXYURIDS 


Diagnosis.    Thelastoma  (Thelastomellum)  myolabiatum  n.  sp.     Dimen- 
sioned as  shown  in  the  formula,  and  with  lips  and  amphids  as  in  Fig.  5. 

3.  SYNGONY  IN  A  NEW  NEMA  FOUND  IN  MILLIPEDS 

Hitherto  undescribed  nemic  parasites  found  in  the  intestine  of  the  milliped 
Fontaria  marginata  Say  and  belonging  to  the  genus  Thelastoma   Leidy, 
prove  syngonic.     Thelastoma  would   be  assigned   by 
most  authors  to  the  group  Oxyuridae. 

The  discovery  of  syngony  in  this  group  opens  up  an 
interesting  field  for  speculation  and  research.  It  has 
long  been  felt  that  the  "Oxyuridae"  present  many 
resemblances  to  the  rhabdites.  The  gonism  of  the 
rhabdites  has  been  found  very  varied,  particularly 
through  the  researches  of  Maupas.  Query:  To  what 
extent,  now,  will  the  variations  exhibited  by  the 
rhabdites  be  found  to  occur  in  the  "Oxyuridae?'' 

Male  "oxyurids"  usually  are  less  common  than  the 
corresponding  females,  quite  frequently  are  rare,  and 
in  some  cases  are  unknown.  The  striking  nature  of 
the  recorded  sex  ratios  has  been  explained  by  saying 
that  the  males,  being  very  much  smaller,  are  easily 
overlooked,  and  that  possibly  they  die  soon  after 
copulation;  and  that  these  two  factors, — their  small- 
ness  and  (assumed)  relatively  early  death, — account 
for  their  supposed  rarity. 

In  the  rhabdites  the  evidence  fully  warrants  the 
matic'drawf^of'tiTfe^  view  that  syngony  has  evolved  from  amphigony  with 
male  gonads  of  ^Thelastoma  a  gradual  diminution  or  disappearance  of  males; — 
"  for  many  stages  between  the  two  extremes  still  exist 
as  evidence  of  the  possibility  of  such  a  change.  There- 
fore the  discovery  of  syngony  in  the  "oxyurids"  at 
once  suggests  a  new  explanation  of  the  scarcity  of 
"oxyurid"  males,  namely,  the  one  now  usually  accepted 
in  many  cases  for  the  rarity  of  male  rhabdites.  If 
this  be  true  of  the  "oxyurids,"  it  may  have  a  con- 
gonicspermsof  sHWoSomd-  siderable  bearing  on  veterinary  and  medical  questions 
lwm'  connected  with  "oxyurid"  parasites  in  man  and 

domesticated  animals,  and  in  other  hosts. 

Species  that  have  been  assigned  to  the  "Oxyuridae"  are  common  parasites 
of  insects  and  some  other  annulata. 


inl 


ordct 


iX40      an. 


(right),    sp.   the.    sperma- 
theca. 


THE  DEMANIAN  VESSELS  IN  NEMAS  OF  THE 
GENUS  ONCHOLAIMUS 

With  Notes  on  four  new  Oncholaims* 

CONTRIBUTIONS  To  A  SCIENCE  OF  NEMATOLOOY  XXIV1 
BY  N.  A.  COBB 

Continuing  the  work  of  deMan,  1884,  and  zur  Strassen,  1896,  observations 
have  been  made  on  Ad&ncholaimus  fuscus  (Bastian),  Metoncholaimus  pris- 
tiurus  (zur  Strassen)  and  other  Oncholaims  (listed  on  p.  425)  with  particular 
reference  to  the  system  of  tubular  organs  discovered  by  deMan.  Building 
on  the  foundation  laid  by  these  eminent  observers,  it  has  been  possible  to 
define  the  demanian  system,  and,  within  limits,  assign  it  a  function.  The 
following  definition  and  table  of  homologous  terms,  together  with  the  accom- 
panying text  appreciably  advance  our  knowledge  of  this  remarkable  system 
of  organs. 

DEFINITION 

Demanian  Vessels: — In  adult  female  nemas  (Oncholaims)  a  complicated 
double  system  of  efferent  tubes;  connecting,  (1),  with  the  middle  or  posterior 
part  of  the  intestine  through  an  osmosium  (see  p.  428),  and  (2),  with  the 
uterus  (or  uteri);  these  two  efferents  being  confluent  at  a  special  glandular 
"gateway,"  the  uvette  (see  p.  427),  and  emptying  thence  backward  and 
outward,  through  one  or  two  ducts  having  more  or  less  moniliform  affluent 
glands  (see  p.  426,  Fig.  1).  Normally,  the  ducts  lead  to  exit  pores  in  the 
body  wall,  usually  laterad,  one  or  more  on  each  side,  near  the  base  of  the  tail. 

In  certain  cases  at  least,  apparently  homologous  tubular  organs  connect 
with  the  gonad  of  the  male  near  the  beginning  of  the  vas  deferens.  For 
example,  in  Metoncholaimus  pristiurus,  Adoncholaimus  fuscus  and  Oncho- 

*  Investigations  carried  on  in  part  at  the  U.  S.  Fisheries  Biological  Station,  Woods 
Hole,  Mass.  The  abbreviations  used  are  mostly  self-explanatory;  e.g.  onch  dsl,  (on- 
chium  dorsale),  dorsal  tooth.  Full  list  of  abbreviations  on  p.  341. 

1  Reprinted  from  the  JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES,  Vol.  20, 
No.  12,  June  19,  1930. 

423 


424 


ORIGIN   AND  TERMINOLOGY  OF   THE  DEMANIAN   SYSTEM 


laimium  appendiculatum  I  observe  a  tubular  glandular  vessel,  outstretched 
forward  and  emptying  backward  into  the  vas  deferens,  that  appears  homol- 
ogous with  parts  of  the  better  known  demanian  system  of  the  females.  See 
Fig.  2. 

In  female  nemas  the  functioning  demanian  vessels  (e.g.  pristiurus)  elabo- 
rate a  copious,  elastic,  sticky,  non-water-soluble,  nearly  colorless  secretion, 
possibly  utilized  ("spun"?)  during  agglomeration  and  copulation,  and  also 
presumably  to  protect  and  preserve  the  batches  of  eggs  after  deposition  and 
during  segmentation. 

The  demanian  organs  seem  to  prevail  in  mud-inhabiting,  and  sand-inhabit- 
ing oncholaims, — i.e.  those  of  stagnant  habitat;  and  to  be  absent  or  less 
prevalent  in  oncholaims  living  in  more  thoroughly  oxygenated  water, — on  the 
surface  of  eelgrass,  and  among  algae,  e.g.  in  Prooncholaimus  Micoletzky, 
1924. 

Origin.  As  to  the  primitive  nemic  tissue  from  which  the  demanian  vessels 
may  have  originated,  we  seem  driven  to  accept  the  primitive  gonadic  tissue  as 
the  probable  source.  The  histology  of  the  demanian  system  reminds  one 
most  strongly  of  the  structure  of  nemic  gonads;  most  of  the  histological 
elements  known  in  the  demanian  system  have  homologues  in  the  gonadic 
system  of  nemas; — while  on  the  contrary  there  is  no  such  tunic,  and  there 
are  no  such  forms  of  nuclei,  known  in  connection  with  the  enteron. 

Equivalent  terms  of  various  authors 


Author,  de  Man 

Author,  zur  Strassen 

Author,  present 

Rohrenformiges  Organ 
Organe  tubiform 

Rohrenformiges  Organ 

Demanian  System 

Hauptrohr  (fuscus) 
Canal  principal  (albidus) 

Stammrohr 

Enteric  efferent 

Verbindung    zur     Stiitze 
Blindes  Vorderende 

Offene  Verbindung 
Mundungsorgan 

Osmosium,  or  Selective  demanian 
intake  (enteric) 

Verbindungsrohrchen  zwischen 
Warze  und  Uterus 
Tube  de  communication 

No  mention 

Uterine  efferent 

Ausf  iihrungsgang  in  den  Uterus 

Blindgeschlossener  Sack 

Demanian  intake  (uterine) 

Warze 
Papille  ovulaire 

Rosette 

Uvette 

Rothbraune  drusen  (fuscus) 
Tubes  latereaux  (albidus) 

Endschlauch  des  Rohrorgans 

Moniliform  Glands 

DIAGNOSES   OF   THE   GENERA   AND    SPECIES   MENTIONED    HEREIN 

ONCHOLAIMINAE  Filipjev,  1918  and  1925 

(but  without  Anoncholaimus,  Pelagonema,  Anoplostoma,  Trilepta,  Krampia. 

Filipjevia.) 


DIAGNOSES   OF  VARIOUS   ONCHOLAIMS  425 

ONCHOLAIMIUM,  n.  gen. 

Monodelphic  Oncholaiminae  with  demanian  system,  whose  males  have  a 
versatile,  preanal,  ventral  appendicule.  See  Figs.  2  and  3. 

Oncholaimium    appendiculatum,   .*.-?. £-.9 *?.• ff'.T*-; »•«• » 

n.  sp.     Oncholaimium  with  appar-   *..».. .    j.       W.  i2M_          oo!r 

ently  deteriorated  moniliform  ***  '  *•*  '-1'"  "  THr"""",^ "iS**^** 
glands  without  exit  pores,  and  with  very  simple  ampulliform  uvette.  Appen- 
dicule "hinged"  and  mobile.  Figs.  2,  3,  8,  9.  Moniliform  glands  24-fold, 
(8  +  16).  Exceptionally  32-fold. 

Oncholaimus      nigrocephalatus    ft».   .J.4      to*.  ***as.  or. 

„      ,     .   .  ,  ao    /    1.6       "1.9 22 an        """ 

n.    sp.    Oncholaimus   with  very    1?      ^      ia  iaM_          00.2 

slightly    compound,    non-refrac-    '*•*  '   *•**       *•* *-5 i-'i.» •>3-4im" 

tive  uvette,  pigmented  head,  and  hemispheroid,  immobile,  preanal,  ventral 
male  supplement;  demanian  system  with  two  rather  inconspicuous  exit  pores, 
eachlaterad;  cells  of  the  rouleaux  (moniliform  glands)  oblique,  little  flattened. 

Oncholaimus  serpens,  n.sp.    On-  f*-T. ?•*. .«: ."!?*-. •^^•>43mm 

cholaimus       whose       moniliform  o!z      T!       12.  .*»**_          pro 

glands  are  vaguely  seriated  but  not  a6  '  *'        *'  "^  *• 

in  rouleaux.     Compound  uvette  not  condensed  and  refractive. 

Metoncholaimus  pristiurus   (z.    ?.•« *?* !*: 

Str.).  Specimens  from  Woods  o'.a  w  11. 
Hole  gave  the  opposite  measure-  0-a '  *•*  w 
ments.  Moniliform  glands  64-fold. 

t    i         j     7     .  .  1.1  T.T          IT.  *33.*  OS  3 

Adoncholaimus  pamcus,  n.  sp.     jia/""»."a a.j» a.i" i'.g^4-1""" 

Adoncholaimus  having  a  transverse  row  of  seven  demanian  exit  pores  on  each 
side.  See  Fig.  7. 

Adoncholaimus  fuscus  (Bast.).    Moniliform  glands  8-  or  16-fold, — see  Fig.  1 . 

One  soon  appreciates  the  weight  of  zur  Strassen's  words  where  he  says, 
in  speaking  of  the  demanian  system  of  various  oncholaims, — "In  fact,  the 
differences  are  such  that,  were  they  equally  pronounced  in  any  other  system 
of  organs,  they  would  lead  to  the  proposal  of  separate  genera,  or  even  families." 

In  this  connection  the  present  studies  lead  to  the  belief  that  the  demanian 
system  not  only  varies  markedly  in  the  different  groups  of  oncholaims,  but 
that  in  all  probability  the  system  is  present  but  has  been  wholly  overlooked  in 
many  of  the  forms  described.  Hence  it  seems  premature  to  attempt  a  com- 
plete subdivision  of  the  oncholaims  into  genera  and  subgenera.  It  may  be 
doubtful  whether  the  genera  and  subgenera  so  far  proposed  are  natural  ones. 
In  particular,  Oncholaimus,  the  group  connected  with  the  type  species 
atte?iuatus,  seems  chaotic;  yet  no  better  course  appears,  at  present,  than  to 
leave  serpens  and  nigrocephalatus  in  this  ill  defined  group: 


426 


UTERINE   EFFERENT 


w  dct: 


uwtte 


int 


Fig.  !•  Amended  diagrams  of  the  demanian  system  of 
M etoncholaimus  pristiurus  (dorsal  view)  and  Adoncho- 
laimus  fuscus  (side  view),  modified  from  the  diagrams 
of  zur  Strassen  and  deMan  respectively,  eff  int, 
enteric  or  intestinal  efferent;  eff  ut,  uterine  efferent; 
vlv,  vulva;  ov  dct,  oviduct;  gl  cdl  (3),  the  three  caudal 
glands;  gl  monl,  the  moniliform  glands;  porus,  exit  pores 
of  the  demanian  system.  Notice  that  in  each  case  the 
uvette  empties  through  a  minute  pore,  the  uvette  pore. 
The  moniliform  glands  in  pristiurus  are  64-fold;  in 
fuscus  8-  or  16-fold. 

Uterine  Efferent.  An  examination  of  Met- 
oncholaimus  pristiurus  (zur  Strassen)  furnishes 
convincing  evidence  that  the  interesting  female 
organ  described  by  zur  Strassen  is  connected  not 
only  with  the  intestine,  as  he  discovered,  but  also 
with  the  uterus  by  means  of  a  tube  (see  eff  ut, 
Fig.  1)  extending  forward  from  the  uvette, — i.e. 
from  the  "rosette"  of  zur  Strassen.  The  evidence 
is  as  follows:  In  many  female  specimens  it  is 
possible  behind  the  vulva  to  follow  backward 
from  near  the  vulva  a  long,  narrow,  apparently 
(not  really)  vacant  space,  reminiscent  of  the 
uterine  efferent  of  Oncholaimium  appendiculatum 
(see  Fig.  3)  which  on  more  careful  examination 
proves  to  be  a  duct.  This  duct,  however,  is  not 
so  refractive  or  of  such  uniform  diameter  as  in 
appendiculatum,  and  is  even  more  difficult  to  see. 
It  varies  slightly  in  diameter.  Here  and  there 
throughout  its  length  it  can  be  seen  to  have  a  thin, 
double-contoured  wall  containing  small  but 
definite,  much  elongated  nuclei.  This  tube  is 
usually  in  a  collapsed  condition,  more  often  pre- 
senting its  edge  toward  the  observer,  but  some- 
times not.  When  it  is  presented  edgewise,  one 
may  often  detect  in  its  thin  wall  the  scattered 
elongated  nuclei,  especially  in  specimens  fixed 
and  stained  in  acetic  acid  methyl  green;  occa- 
sionally nuclei  can  be  seen  also  in  other  views. 
Examining  the  requisite  number  of  specimens 
leads  to  the  conclusion  that  from  the  uterus  near 
the  vulva  the  duct  arises  dorsad  as  a  broad  tube, 
directed  backward,  which  narrows  rapidly  and  ex- 
tends along  the  right  side  of  the  nema,— approxi- 
mately along  the  right  lateral  chord  though 
not  necessarily  exactly  opposite, — and,  expanding, 
joins  and  envelopes  the  uvette.  See  Fig.  1. 


UVETTE  427 

Uvette*.  The  "warze"  of  deMan,— i.e.  the  "rosette"  of  zur  Strassen,— is 
the  structure  to  which  I  apply  what  seems  the  more  appropriate  name 
"uvctte."  Comparisons  show  that,  notwithstanding  the  very  marked  dif- 
ferences in  form,  the  various  organs  herein  called  uvettes  are  homologous; 
the  same  is  true  of  those  called  monil  form  glands. 

The  uvette  of  Adoncholaimus  fuscus  (Bastian)  as  illustrated  by  deMan 
probably  presents  32  elements  (Kornchen,  deMan's  Fig.  29)  as  does  that  of 
M .  pristiurus;  these  elements  have  been  outlined  by  deMan  and  figured  some- 
what more  in  detail  by  zur  Strassen  (deMan's  Figs.  24,  29;  zur  Strassen 's 
Figs.  13,  14). 

In  favorable  specimens  I  have  seen  the  uvette  of  fuscus  to  be  a  "radial" 
structure  made  up  of  about  32  elements  surrounding  a  minute  pore,  somewhat 
as  in  the  uvette  of  pristiurus,  (See  Fig.  1)  but  the  elements  here  are  far  less 
refractive.  Rarely  can  one  see  the  appearance  illustrated  by  deMan  in  his 
figure  29;  whereas  the  appearance  he  does  not  satisfactorily  illustrate, — a 
very  complicated  one,  by  the  way, — is  the  usual  appearance;  and  when  this 
appearance  is  more  pronounced,  commonly  the  minute  refractive  "Kornchen" 
that  deMan  figures  are  not  to  be  seen,  or  only  some  of  them  faintly.  DeMan's 
"Kugel,"  figured  by  him  as  if  nearly  round,  I  find  seldom  round  or  ball-shaped; 
frequently  it  is  so  "collapsed"  (?)  as  to  be  difficult  to  see  at  all,  and  it  is  more 
likely  to  be  elongate  or  ellipsoidal,  or  perhaps  flattish-ellipsoidal,  than  to  be 
equidiametral  as  shown  in  deMan's  Fig.  29. 

DeMan  does  not  give  a  thoroughly  satisfactory  description  or  figure  of 
his  "Warze."  In  one  of  his  figures  (Fig.  29)  I  count  33  minute,  circular,  dot- 
like  elements  where  he  makes  his  "Verbindungsrohrchen"  join  the  "Warze." 
Occasionally  I  also  see  this  appearance,  and  with  about  the  same  number  of 
elements  (32?).  It  is  difficult  to  say  as  yet  what  the  exact  function  of  the 
uvette  is,  but  it  seems  a  regular,  doubtless  glandular,  component  of  the 
demanian  system.  In  Oncholaimium  appendiculatum  the  uterine  vessel, 
extending  backward  from  the  uterus,  nearly  as  described  for  pristiurus, 
finally  expands  a  trifle  into  a  small,  often  rather  indefinite,  ampulliform 
uvctte  of  the  very  simplest  character,  which  joins  the  right  subdorsal  of  the 
two  longitudinal  series  of  cells, — the  moniliform  glands, — by  means  of  a 
minute  refractive  pore, — the  uvette  pore.  See  uv,  Fig.  3.  In  Oncholaimus 
nigrocephalatus  the  uvette,  which  in  0.  appendiculatum  appears  as  a  simple 
ampulla,  becomes  somewhat  compound;  that  is  to  say,  two  additional  or 
subordinate  elements  occur,  one  on  either  side  of  the  main  "ampulla,"  so 
that  the  whole  is  rather  obscurely  triplex. 

In  another  oncholaim,  Oncholaimus  serpens  n.  sp.,  the  uterine  tube  extends 
backward  just  as  definitely  as  in  Oncholaimium  appendiculatum  and  joins 
the  rest  of  the  demanian  system  in  the  form  of  an  expanded  and  much  larger 

*  Uvette ;  a  diminutive  cluster.    From  latin,  uva,  a  cluster  of  grapes. 


428 


MALE    ONCHOLAIMIUM.       OSMOSIUM 


uvette,   rather  closely  resembling  one  of  the  uvettes  of 
*          Adoncholaimus  fuscus.     In  0.  serpens  the  elements  are  not 
u   nearly  so  refractive,  and  the  somewhat  pyriform  whole  is 
so  symmetrical ;  but  it  is  made  up  of  radiating  elements 
•"l*arr  having  some  resemblance  to  those  composing  the  uvette  of 
••P(K  pristiurus. 

ili  i  nn  isi  not  sfunct  or  sum  .nit  ,  sub  ail  Osmosium.  Moniliform 
..mesa  glands.  In  addition,  I 
.din/M  have  established  to  my 
satisfaction  that  the  main 
tube  of  the  demanian  sys- 
tem in  Adoncholaimus  fus- 
cus, which  was  described  by 
deMan  as  probably  being 
merely  fastened  anteriorly 
to  the  intestine,  and  there- 
fore regarded  by  him  as 
probably  merely  a  holdfast, 
is  in  reality  in  communica- 
tion with  the  intestine  by 
means  of  what  I  have 
called  an  osmosium.*  It 
has  much  the  same  struc- 
ture as  that  described  by 
zur  Strassen  for  Metoncho- 
laimus  pristiurus  and  M. 
deMani  (zur  Strassen,  Figs. 
4  to  12),— and  which  I 
have  examined  in  pris- 
tiurus,— except  that  there  is 
no  open  communication. 
There  are  no  essential  differ- 
0  ences  in  the  structure  of 
&  &  the  enteric  junctions  of  the 
arson  silmit'  'tut  nsrsm 

Xig.2.Ma.leOnchclaimiumappendi-      *  Osmosium;  that  part  of  an 
culatum  n.g.,n.sp.,  drawn  from  a  fixed  emunctorium  or  analogous  or- 
and  stained  balsam  specimen.     The  gan  through  which,  mainly  by 
locus  of  the  cross  section  drawing  is  osmotic  action,  soluble  matter 
ar  shown  at  locusx-sec.  ac  gon,  accessory  is  transferred  from  one  organ  to 
to    gonad;    al'm'nt,    food    material;  another.     The     osmosium     is 
appndl,   appendicule;  chrsm  hap  14,  here    not    emunctorial.     It    is 
.one  haploid  number  of  chromosomes ;  jnc  still  doubtful  whether  the  os- 
aasff  ^s'>    Junction   °f   testes;    ncll    spmct,  motic  cells  in  this  particular 
nucleolus;    ncl    spmtd,     nucleus    of  case  are  of  enteric  or  deman- 
srtaiha.L'  spermatid;  orginq,  organs  of  uncertain  ian  origin.     While  the  staining 
function;  os  ac  gon,  mouth  of  accessory  of  these  cells  seems  to  favor  de- 
to    gonad;   spmct,   sprmatocyte;   tst  manian    origin,    the    structure 
(175  ant,— front  testisjr,  its  cross-section,  seems  to  favor  enteric  origin. 


FEMALE    ONCHOLAIMIUM.      MONILIFORM   GLANDS 


429 


various  oncholaims  I 
have  examined,  except 
minor  ones  in  the  more 
or  less,  but  very  ob- 
scurely, radiating  part 
that  sets  into  the  wall 
of  the  intestine.  This 
part  forms  an  "os- 
motic" exit  through  the 
the  intestinal  wall  in 
the  shape  of  special, 
presumably  metabolic 
and  at  least  selective, 
glandular  tissue  of  the 
osmosium. 

In  the  species  Oncho- 
laimus  nigrocephalatus 
there  are  external  lat- 
eral exit  pores  in  the 
anal  region  much  as  in 
pristiurus  but  they  are 
minute.  Thus  far,  how- 
ever, I  have  searched  in 
vain  for  these  pores  in 
Oncholaimium  appen- 
diculatum. 

In  this  latter  species 
there  are  two  monili- 
form  subdorsal  series  of 
24  cells  each  which  I 
propose  to  call  monil- 
iform  glands.  These 
are  rather  close  homo- 
logues  of  the  64-fold  rou- 
leaux of  zur  Strassen; 
less  obviously,  of  the  8- 
or  16-fold  "Rothbraune 
driisen"  of  deMan.  The 
uterine  vessel  joins  the 
right  hand  one  of  these 
moniliforrn  glands,  as 
is  shown  near  the  mid- 
dle part  of  figure  3 
on  this  page,  at  uv. 


Fig.    3.  Female    of   Oncholaimium 
appendiculatum    n.g.,   .n.sp.,    drawn 
from   living   specimen   under   slight 
pressure.    The    uterine    efferent    is 
shown  from  where  it  joins  the  uterus 
at  ut  eff  to  where  it  joins  the  right 
moniliform  gland  at  uv,  the  uvette; 
gl     monil,     moniliform     glands;     gl 
dxt,     the     right     hand     moniliform 
gland;  gl  sns,  left  hand  moniliform 
gland;  crystal,  tetrahedroid  (?)  crys- 
tals on  the  outer  surface  of  the  enteric 
efferent;    eff  int,    the    intestinal   or 
enteric  efferent;  lum  ut,  lumen  of  the 
uterus;  del  cdl,  the  three  caudal  ducts; 
chrd  lat,   borders  of  the  right  hand 
lateral    chord;    amph   extr,    external 
amphid;  spm,  sperm ;  ncl  spm,  nucleus 
of  one  of  the  sperms;  trm  ov,  blind  end 
of  the  single  ovary;  ov  tegmt,  shell  of 
the  egg;  div  secnd,  second  division  of 
the    nucleus    of 
female     gamete;  aa/i//ixtr.. 
plrcyt,  polarcyte; 
ov  in  dct,  much 
elongated       egg  op/to 
passing    through 
the  oviduct  from  a/raaipi  . 
the  ovary  to  the  / 
uterus;  pst,  pus-     ' 
tules  due  to  uri-  ,-////r 
tis;  grn  bifr  bire-      / 
fringent  granules  '"' 
in  intestinal  cells.   /    , 


nap  s/m 


*175 


430  ENTERIC   EFFERENT 

In  0.  appendiculatum  at  the  posterior  end  of  the  two  24-cell  moniliform 
glands,  however,  a  number  of  the  cells  of  each  organ  seem  loosened  from  the 
series;  opposite  these  I  am  unable  to  find  any  outlet  whatever; — that  is  to  say, 
the  organs  appear  as  if  in  a  deteriorated  condition.  See  gl  dxt,  gl  snst,  Fig.  3. 

Perhaps  causally  connected  with  this  is  the  extraordinary  fact  that  the 
examination  of  hundreds  of  females  of  Oncholairnium  appendiculatum  over 
a  number  of  years  has  failed  to  disclose  a  single  healthy  specimen.  Every 
female  is  attacked  by  a  disease  that  often  results  in  necrosis  of  the  posterior 
portion  of  the  nema.  (See  section  Uritis,  p.  240).  The  disease  (uritis) 
breaks  out  on  the  tail  in  the  shape  of  minute  pustules  having  an  internal 
radiated,  or  linear  and  "parallel-fibered,"'  structure,  pst,  Fig.  3,  sometimes 
extending  forward  for  a  considerable  distance  into  the  nema, — in  extreme 
cases,  as  far  forward  as  the  vulva.  There  may  be  one,  two,  three,  or  even  as 
many  as  a  dozen  of  these  pustules  irregularly  scattered  on  the  posterior  part 
of  the  female.  The  pustules  are  minute,  exude,  inter  alia,  an  insoluble 
material,  and  frequently  exhibit  surface  bacteria,  though  it  seems  doubtful 
if  the  bacteria  thus  far  seen  are  connected  \vith  the  disease.  The  uniform 
occurrence  of  this  disease  in  females  of  Oncholaimium  appendiculatum  may 
perhaps  be  connected  with  the  deteriorated  (?)  condition  of  the  demanian 
system.  On  a  later  page  attention  will  be  called  to  the  fact  that  other  on- 
cholaims  possessing  the  demanian  system  have  what  appear  to  be  similar 
diseases  of  the  posterior  extremity;  but  in  none  of  them  is  there  any  such 
extraordinary  condition  as  in  0.  appendiculatum,  where  examination  has 
failed  to  disclose  a  single  adult  female  free  from  uritis. 

Enteric  Efferent.  Against  the  idea  that  in  Adoncholaimus  fuscus  the 
anterior  junction  of  the  demanian  system  with  the  intestine  is  merely  a  hold- 
fast, as  suggested  by  deMan,  it  may  be  urged  that  of  other  elongated  organs 
known  to  lie  loose  in  the  body  cavity  of  nemas,  none  are  secured  in  this 
particular  way  to  the  intestine.  Why  an  exception  in  this  case?  If  it  is 
merely  a  matter  of  security,  it  would  seem  more  in  harmony  with  known 
nemic  anatomy  that  the  attachment  be  to  the  body  wall  rather  than  to  the 
intestine,  and  especially  that  it  be  effected  along  a  lateral  chord.  It  is  not 
unheard  of  for  a  nemic  organ  of  this  general  form  to  be  attached  to  a  lateral 
chord. 

From  a  mechanical  point  of  view  the  idea  that  the  connection  of  the 
demanian  system  with  the  intestine  is  merely  a  holdfast  seems  to  have  all  the 
less  to  recommend  it  in  the  case  of  the  monodelphic  species,  such  as  pristiurus 
and  serpens,  where  this  connection  is  so  far  caudad  that  such  a  holdfast  seems 
rather  needless. 

DeMan's  idea  that  his  main  tube  is  simply  and  only  fastened  to  the  intestine 
seems  not  borne  out  by  facts;  and  his  figure  25,  if  I  understand  it,  admits  of  a 
different  interpretation.  I  find  his  "main  vessel"  anteriorly  to  be  hollow  to 


NO   OPEN   CONNECTION  431 

its  very  end, — the  "blind  end"  of  dcMan, — and  that  the  freely  moving  con- 
tents of  the  tube  are  visible  clear  to  what  might  be  called  the  surface  tissue 
of  the  intestine  (tissue  of  the  intestine  altered,  to  be  sure).  DeMan's  figure 
25  seems  easily  to  admit  of  this  interpretation.  I  find  the  cells  of  the  wall  of 
the  intestine  (if  they  be  really  intestinal)  are  altered  where  the  vessel  is 
attached,  and  this  fact  suggests  that  we  have  here  modified  selective  tissue  — 
the  osmosium, — the  function  of  which  is  to  extract  from  the  intestine  and 
usher  into  the  demanian  system,  presumably  mainly  by  osmosis,  a  product 
utilized  by  the  latter. 

May  not  the  evidence  offered  by  zur  Strassen  for  an  open  communication 
between  the  enteric  efferent  and  the  intestine  in  pristiurus, — i.e.  the  evidence 
of  his  microtome  sections, — be  capable  of  a  different  interpretation?  Could 
zur  Strassen's  sections  have  been  deceptive?  The  published  figures  of  his 
"open  connection"  between  the  demanian  system  and  the  intestine  are  not 
satisfying,  in  that  they  appear  to  show  a  large  portion  of  the  cell  walls  missing. 
Now  pristiurus  ingests  mud,  and,  in  consequence,  its  intestine  normally 
contains  much  fine  grit.  Is  it  not  likely  that  this  grit,  acting  as  it  naturally 
would  during  the  sectioning,  would  damage,  or  even  destroy,  delicate  cells 
that,  before  being  broken,  might  have  closed  the  aperture  which  zur  Strassen 
shows  and  describes  as  an  open  connection?  The  suggestion  is  that  this  might 
occur,  at  the  time  the  sections  were  cut,  through  the  combined  abrasive 
action  of  the  grit  and  the  coincident  dulling  of  the  microtome  knife.  All 
zur  Strassen's  figures  show  the  intestinal  lumen  more  or  less  open;  but  when 
the  intestine  is  entirely  empty  and  free  of  grit  it  is  collapsed,  not  open,  so  that 
the  lumen,  in  well  made  sections,  is  closed  and  difficult  to  see.  May  not  this 
indicate  that  the  vacant  lumenal  spaces  shown  in  zur  Strassen's  illustrations 
probably  did  contain  grit  at  the  time  of  fixation,  and  hence,  no  doubt,  at  the 
time  of  sectioning? 

Pristiurus,  fuscus  and  some  other  mud-inhabiting  Oncholaims  can  be  kept 
alive  in  pure  running  sea  water  for  days,  or  even  weeks,  and  when  so  kept 
evacuate  the  intestine  very  completely.  Sections  may  then  be  made  without 
the  interference  of  the  grit  normally  present  in  the  intestine.  /  have  not  found 
such  sections  to  present  the  appearance  figured  by  zur  Strassen. 

In  an  examination  of  very  many  specimens,  alive  and  sectioned,  I  have 
never  been  able  to  convince  myself  of  the  existence  of  an  open  communication 
between  the  intestine  and  the  demanian  system. 

Any  such  open  connection  would  seem  a  grave  menace  to  the  well-being 
of  the  organism.  For  if  the  enteric  intake  were  of  the  nature  figured  and 
described  by  zur  Strassen,  there  would  seem  to  be  little  or  nothing  to  prevent 
the  entrance  into  the  demanian  system  of  undigested  detritus  contained  in 
the  intestine,  together  with  numerous  living  microorganisms  which  normally 


432  UTERINE    EFFERENT 

constitute  a  very  appreciable  part  of  the  feces.  No  such  detritus  is  ever 
seen  in  the  demanian  system. 

Furthermore,  on  examining  living  pristiurus  &nd  fuscus,  both  of  which  I  find 
to  occur  along  Cape  Cod,  U.  S.  A.,  I  find  that  when  the  food  in  the  intestine 
is  moving  rapidly  back  and  forth  opposite  zur  Strassen's  supposed  open 
connection,  no  portion  of  it  ever  enters  the  enteric  efferent.  There  is  not 
even  the  slightest  corresponding  disturbance  of  the  contents  of  the  lumen  of 
the  enteric  efferent  close  by,  which,  as  zur  Strassen  also  points  out,  can  be 
seen  in  the  end  portion  of  the  demanian  tube  where  it  joins  the  surface  of  the 
intestine. 

Possibly  the  analogous  connection  with  the  uterus  is  hardly  to  be  taken  as  a 
very  distinctly  open  one.  True,  I  have  seen  cases  in  pristiurus  where,  when 
the  diseased  uterus  was  filled  with  microorganisms  (microorganisms  causing 
the  disease*),  the  continuous  mass  of  them  also  filled  the  nearby  part  of  the 
corresponding  demanian  vessel  in  such  a  way  that  there  was  a  direct  "tubular" 
connection  between  the  uterus  and  the  vessel.  Normally,  however,  the 
conditions  are  as  follows: — One  traces  the  uterine  demanian  vessel  directly 
forward  to  the  uterus,  where  its  lumen  continues  for  a  short  distance  into  a 
glandular  tissue  in  the  posterior  end  of  the  uterus, — zur  Strassen's  so-called 
"blind  end,  behind  the  vulva," — and  there  ceases  in  the  midst  of  a  large 
number  of  uterine  cells  somewhat  similar  to  many  of  those  constituting  the 
main  portion  of  the  wall,  i.e.  what  seems  to  be  a  special  collection  of  glandular 
uterine  cells.  In  fuscus  this  same  thing  occurs  where  the  oviducts  join  the 
proximal  ends  of  the  two  uteri,  not,  as  in  pristiurus,  at  the  posterior  portion 
of  the  single  uterus  close  to  the  vulva;  the  histology  of  this  junction,  however, 
is  much  the  same  in  these  two  species.  It  is  as  if  special  uterine  cells  were 
devoted  to  secreting  material  to  be  deli vered  to  the  demanian  system  through 
the  uterine  efferent, — the  "tube  de  communication"  of  deMan. 

In  pristiurus  the  long  tubular  vessel  connecting  the  uterus  with  the  de- 
manian system, — the  uterine  efferent, — often  is  difficult  to  see,  especially  in 
its  entirety.  No  better  proof  of  this  could  be  required  than  that  it  escaped  so 
keen  an  observer  as  zur  Strassen. 

Even  in  Adoncholaimus  fuscus,  while  the  two  short  uterine  efferents  can 
sometimes  be  followed  from  the  uteri  to  the  main  vessel  of  the  demanian 
system,  often  it  is  practically  impossible  in  a  given  specimen  to  follow  them 
throughout  their  course.  Knowing  their  locality  and  structure,  one  can 
usually  determine  how  they  lie  and  their  probable  limits,  but  that  is  about  all. 
Of  course,  in  a  small  minority  of  favorable  poecimens  quite  the  contrary  is 
true; — the  entire  tube  can  be  made  out  satisfactorily  as  was  first  done  by 
deMan. 

*  This  disease  appears  to  have  nothing  to  do  with  uritis  (see  p.  240) ;  uritis  seems  an 
entirely  distinct  disease. 


NATURE  OF  THE  DEMANIAN  FLUIDS  433 

Direction  of  Flow  in  the  Demanian  System.  Evidently  a  considerable 
amount  of  matter  is  contributed  by  the  intestine  to  the  demanian  system. 
Zur  Strassen  had  no  difficulty  in  assuming  the  entire  amount  to  be  so  con- 
tributed in  pristiurus  (for  he  appears  to  have  been  unaware  of  the  connection 
in  pristiurus  of  the  uterus  with  the  uvette,  and  hence  with  the  demanian 
system). 

However,  quite  frequently  in  the  contents  of  the  enteric  efferent  of  living 
Metoncholaimus  pristiurus  near  and  in  front  of  the  uvette  pore,  refractive, 
curved,  wave-like  effects  are  seen  such  as  would  be  produced  by  the  gradual 
mixing  of  two  viscid  fluids  of  unequal  refractiveness, — an  appearance  that 
might  readily  be  produced  by  the  flowing  of  a  liquid  through  the  uvette 
pore  from  the  uterine  efferent  into  the  enteric  efferent  in  such  quantity  that 
some  of  it  passed  slightly  forward, — perhaps  through  cover  glass  pressure. 

On  various  occasions,  I  have  seen  a  considerable  quantity  of  matter  in 
the  main  enteric  vessel  close  to  its  junction  with  the  intestine.  While  this 
is  no  proof  that  this  matter  was  actually  derived  from  the  intestine,  it  is 
favorable  to  that  conception.  Such  matter  never  contains  intestinal  debris, — 
nor  sperms  (see  F.  H.  Stewart,  1906),  nor  pseudo  eggs, — "balls  of  finely  gran- 
ular substance,"  (see  zur  Strassen.) 

If  the  demanian  system  emptied  into  the  intestine,  it  is  to  be  expected  that 
it  would  do  so  through  an  aperture,  pore,  similar  to  those  of  other  affluent 
enteric  glands, — those  emptying  into  the  oesophagus  for  instance.  In  nemas 
such  pores  are  extremely  small,  have  a  definite  refractive  lining,  and  are 
adapted  to  check  any  "backwash"  due  to  movement  of  the  contents  of  the 
enteron, — e.g.  just  such  a  structure  as  occurs  in  the  uvette  of  pristiurus. 
But  no  such  pore  has  been  seen  in  connection  with  any  enteric  demanian  vessel. 

Moreover,  against  the  flow  of  any  of  the  demanian  fluids  being  toward  the 
enteron,  it  may  be  urged  that  in  pristiurus  a  special  secretion  is  at  times 
actually  seen  issuing  rather  copiously  from  the  pores  near  the  tail, — the 
external  outlets  of  the  demanian  system, — and  there  is  not  the  slightest 
reason  to  suppose  that  in  this  region  the  flow  is  ever  anything  but  backward 
and  outward.  There  is  no  evidence  that  the  demanian  system  is,  for  in- 
stance, a  water- vascular  system;  or  that  sea  water  is  taken  in  through  the 
antecaudal  lateral  pores. 

Again,  there  is  little  if  any  reason  to  believe  the  demanian  system  accessory 
to  digestion,  because  whatever  digestive  function  would  be  advantageous  to 
adult  females  would  seem  also  to  be  advantageous  to  the  young  nemas;  yet 
there  are  no  such  organs  in  young  oncholaims,  for  they  come  into  existence 
at  the  last  moult.  The  same  may  be  said  of  any  supposable  ordinary  excre- 
tory function. 

But  if  it  be  supposed  that,  for  some  unexplained  reason,  adult  egg-producing 
females  require  to  excrete  (not  secrete)  matter  peculiar  to  them,  in  other  words 
that  the  demanian  system,  or  some  part  of  it,  be  a  sort  of  temporary  mal- 


434  FLOW    OF   THE    UEMANIAN    FLUIDS 

pighian  system, — a  rather  violent  supposition, — it  would  seem  that  the 
excretion,  as  such,  if  poured  into  the  intestine  at  all,  should  be  poured  in 
posteriorly.  But  in  didelphs,— -fuscus,  panicus, — such  a  supposition  would 
pour  it  in  near  the  anterior  end.  Or,  if  it  be  supposed  that  the  demanian 
system  is  simply  an  emunctorium  accessory  to  the  intestine  and  emptying 
outward  and  backward,  then  why  the  attachment  to  the  fore  part  of  the 
intestine  as  in  fuscus! 

If  the  demanian  system  is  excretory,  then  it  is  necessary  to  assume  that 
the  necessities  of  adult  females  in  the  way  of  excretion  are  different  from  those 
of  the  male  or  the  young  female.  No  reason  has  been  advanced  for  such  an 
assumption. 

Deduction  by  Elimination.  In  the  demanian  system  of  0.  pristiurns 
three  ducts  come  together  at  a  single  point,  indicated  by  X  in 
figure  4, — ducts  in  each  of  which  a  fluid  may  conceivably  flow 
in  either  direction;  i.e.,  there  are  six  different  paths  along 
which  fluid  may  be  conceived  to  flow.  The  assumption  is,  of 
course,  that,  when  the  organs  are  functioning  normally,  fluid 
passes  constantly  in  one  direction  only  in  each  of  the  three 
tubes,  1,  2, 3,  Fig.  4. 

Indicating  the  six  possible  paths  by  arrows  lettered  a,  b}  c, 
d,  e,  f  (Fig.  4),  mathematically,  there  are  twenty  possible 
combinations  in  groups  of  three  as  follows: 

abc,  abe,     acd,     acf,     adf,     Me,     cde,     cef,     bef,     bcf. 

abd,  abf,    ace,    ade,    bed,     bdf,    cdf,    aef,     bee  and  def;—    Of  the  six°pos- 
this  is  according  to  the  formula  for  combinations,  s^'^c  currents. 

n(n-l)  (n-2) (n-r  +  1)        GX5X4 

-  = 


Fig.  5.  Diagram  showing  the  direction  of  flow  of  the  fluid  in  the  demanian  system. 
The  intestine  and  the  posterior  end  of  the  uterus  are  shown  near  bde .  The  backward 
flow  of  the  fluid  in  the  enteric  and  uterine  efferents  is  indicated  at  b  and  d,  and  the 
backward  flow  of  their  combined  products  at  e.  The  outward  flow  of  the  fully  elabo- 
rated secretion  after  it  has  passed  the  moniliform  glands  is  shown  by  the  two  oblique 
black  arrows. 

It  is  evident  that  a  combination  containing  a  and  6  represents  a  physical 
impossibility,  i.e.  represents  opposite  currents  simultaneously  in  the  same 
duct, — duct  number  1 ;  and  so  with  combinations  containing  c  and  d,  and  e 


FLOW   OF   THE    DEMANIAN   FLUIDS 


435 


and  /.  (It  is  theoretically  possible,  of  course,  that  the  same  tube  might  have 
a  flow  in  one  direction  at  one  time  and  in  the  opposite  direction  at  another 
time,  but,  physiologically  speaking,  this  is  an  unusual  occurrence,  and  prac- 
tically an  unheard  of  thing  in  a  tubular  organ  "open"  at  both  ends).  We 
may  therefore  eliminate  from  the  20  possibilities,  12  of  the  combinations, 
leaving  eight, — acf,  adf,  bcf,  ade,  bee,  bde,  bdf  and  ace. 

But  there  are  also  two  more  combinations  that  obviously  must  be  left  out, 
as  involving  physical  and  physiological  impossibility,  namely  ace  and  bdf, 
i.e.,  the  cases  where  the  three  currents  would  simultaneously  come  to,  or 
radiate  from,  the  point  X;  bdf, — (no  outlet,  or  reservoir),  and  ace, — (no 
obvious  source  of  supply).  This  leaves  six  combinations  possibly  worthy  of 
discussion,  acf,  adf,  bcf,  ade,  bee  and  bde.  These  six  possibilities  are  dia- 
grammed in  figures  5  and  6.  Five  of  these  possibilities  (Fig.  6)  are  rendered 


I.  No  exit  pore  for  a;  pore  of  uvette  indicates 
reverse  of  c;  /  doubtful  because  entrance  of 
sea  water  is  possibly  involved,  while  outflow 
of  secretion  is  known  from  lateral  pores,  p. 

II.  No  exit  pore  for  a;  f  doubtful  as  in  I;  monili- 
form  glands  are  believed  here  to  empty  out- 
ward because  of  their  form  and  location  in  (). 
fuscus;  only  outlet  of  d  and  /  would  be 
through  a. 

III.  c  doubtful  as  in  I;  /  very  doubtful  as  in  I 

and  II;  the  only  outlet  for/  and  b  would  be     If 
through  the  uvette  and  c,— reverse  of  direc- 
tion indicated  by  structure. 

IV.  No  exit  pore  for  a;  the  only  source  of  a  would 
be  d  and  the  uvette. 


V.  c  doubtful  as  in  I;  c  may  also  be  reasoned 
against  on  the  basis  of  homologous  structures 
in  O.  nigrocephalalus  and  0.  appendicu- 
lalum. 

Fig. 


Fig.  6.  Five  diagrams  of  supposed  currents  in^a  demanian  system, 
h  supposition  are  listed  opposite  its  diagram.     Compare  with  Fig.  5. 


Objections  to 


exceedingly  improbable  by  the  physiological  and  morphological  considera- 
tions listed  opposite  their  diagrams.  We  may  therefore  safely  deduce,  even 
from  this  single  discussion,  that  the  flow  is  almost  certainly  as  shown  in  Fig.5. 
The  significance  of  seven  exit  pores  on  each  side  in  panicus  (see  Fig.  7)  is 
an  interesting  subject  for  speculation.  It  can  hardly  be  said  that  the  exist- 
ence of  seven  pores  is  for  the  purpose  of  furnishing  a  large  outlet;  it  would 
seem  much  simpler  to  attain  such  a  result  by  having  a  larger  single  pore.  Nor 


436 


MULTIPLE    OUTLETS    IN   THE    DEMANIAN    SYSTEM 


does  it  seem  that  the  multiple  outlet  would  have  anything  to  do  with  the 
quality  of  the  secretion  that  is  prepared.  The  most  reasonable  supposition 
is  that,  in  use,  the  demanian  secretion  is  rendered  more  effective  through  a 
multiple  delivery,  and  it  is  not  difficult  to  reason  out  why  this  might  be  so. 

Take,  as  a  basis  of  reasoning,  the  fact  that  spiders  have  multiple  spinneret 
tubes.  This  plurality  is  an  advantage  in  that  if  some  tubes  of  the  spinneret 
apparatus  do  not  act,  or  are  restrained  from  acting,  the  remaining  ones  may 
continue  to  act,  an  economy  of  a  kind  often  seen  in  nature.  Thus  threads 
of  varying  size  and  composition  can  be  "spun."  It  seems  not  unlikely 
that  the  multiple  thread  of  the  spider  may  have 
dnldsf.  effdlt  fsc  structural  advantages;  at  any  rate  it  is  a  fact  that, 
in  some  cases  at  least,  the  thread  can  be  artificially 
split  into  components  harmonizing  in  number 
with  the  elements  of  the  spinneret  apparatus. 
If  these  be  advantages,  it  is  quite  conceivable  that 
***  they  may  apply  in  some  way  to  the  multiporous 
Adoncholaimus  panicus,  and  this  would  harmonize 
with  the  previous  conclusions  concerning  the 
function  of  the  demanian  system; — for  presum- 
ably the  secretion  in  panicus  is  like  that  of  other 
oncholaims,  i.e.  a  copious,  sticky,  non-water- 
soluble,  elastic  material; — at  least  these  arc  its 
properties  after  it  is  delivered  into  sea  water  by 
pristiurus. 

The  location  of  the  outlets  of  the  demanian 
system  is  always  well  caudad,  and  the  oncholaims 
having  the  system  are  agile  and  limber,  all  of  which 
harmonizes  with  the  belief  that  the  system  elabor- 
ates material  used  with  some  degree  of  "skill." 
Fig.  7.  Adoncnolaimus  .  „  ,  ,  .  ,  .,  , 

panicus  n.sp.  Side,  ven-  All  oncholaims  having  the  demanian  system 
tral  and  sectional  views  of  have  a  habit  of  coiling  and  uncoiling  and  can  with 
the  posterior  portion  of  the  ,  ij.i»-i  r,i 

same  female,  eff  prep,  the  the  greatest  ease  place  the  exit  pores  of  the  system 
principal  efferent  at  the  against  any  part  of  the  body  except  the  tail  and 
point  where  it  forks  to  pro-  ...  ,.  ,  .  .  .,  ,  ,,  .  ,  ,  .,  ,  ,  , 

duce  the  two  deltic  effer-  its  immediate  vicinity,  and  this  habit,  no  doubt, 
ents,  eff  dlt;  the  seven-fold  js  correlated  with  the  function  of  the  secretion, 
delta  is  shown  at  delta  and  _.  .  ,  ,  i  i  .  7  7.77 

the  seven  exit  pores  at  exit.  Females  of  such  oncholaims  have  relatively  short 

tails, — as  if  longer  ones  would  perhaps  be  in  the  way. 

Conceivably,  of  course,  the  demanian  secretion  might  have  properties 
attractive  to  the  other  sex  (odor,  etc.),  but  the  idea  does  not  seem  to  appeal 
so  strongly  as  that  of  having  something  to  do  with  other  matters. 

In  this  connection  it  may  be  recalled  that,  opposite  the  demanian  exit 
pores  of  Metoncholaimus  albidus  (Bastian),  deMan  described  and  figured  a 
persistent  girdle  of  left-over  yellowish  brown  secretion. 


USES   OF   THE   DEM  AN  IAN   BECEET1ON 


437 


Oncholaims  having  the  demanian  system, 
at  least  most  of  them,  have  a  way  of  collecting 
together  in  masses  when  artificially  assembled 
in  sea  water.  Conceivably  this  habit  may 
have  some  connection  with  the  demanian 
secretion,  but  it  is  not  obvious  why  only  adult 
females  should  secrete  for  this  purpose  alone. 

The  demanian  system  appears  more  dis- 
tended when  the  uterus  is  full  or  nearly  full  of 
eggs.  For  instance,  at  this  time  the  uterine 
efferent  and  portions  of  the  uterus  of  pristiurus 
may  contain  an  abundance  of  colorless,  trans- 
parent, rather  structureless-looking  matter, 
resembling,  under  the  microscope,  partially, 
dissolved  shavings  of  gelatin. 

The  question  arises  as  to  what  becomes  of  the 
secretion  of  the  accessory  gland  of  the  male,  Fig-  8-  Profile  of  head  end  of  male 
which  is  possibly  or  probably  a  homologue  of  §£^S^2?±^Si 

the  demanian  system  in  the  female.  No  reply  }eft  ventral  submedian  is  the 
. ,  .  ,  ,  .  longest, — see  on  dsl  and  on  subm 

to  this  question  has  occurred  in  connection  (#).    The  sensilla  and  amphidial 

with  these  investigations  except  that  the  "gum  nerye  are  shown.  Nuclei  shown 
,.,.,„  .  ,  .  .«.  ,.  mostly  central  nervous  system; 

arabic-like"    mixture   seen   in  the   uterus    of  the  scattered  darker    ones   are. 

pristiurus  might  possibly  have  been  derived  o^lei  of  the  lateral  chord,  the 

•_,    «.  ,    ,          ,,  ,         ,,     ,       ,  ,   width  of  which  is   pointed  out 

wholly  or  in  part  from  the  male.     It  should  &tchrdlat. 


perhaps  be   mentioned    that 


X350 

Fig.  9.  Tail,  male  Oncholaimium 
appendiculatum.  ppl,  single  ven- 
tral papilla;  del  (3),  caudal  ducts 
leading  to  spinneret;  appndl, 
ventral,  erectile  appendicule;  an 
set,  anal  setae ;  set  subm  (12),  sub- 
median  setae  on  male  only. 


in    the    nemic 

genus  Rhabditis,  glands  accessory  to  the 
male  gonad  are  known  that  secrete  a  copu- 
latory  cement;  but  no  such  cement  is  yet 
known  in  connection  with  any  oncholaim. 

Of  course,  the  mere  presence  of  this 
material  in  the  uterus  and  in  the  portion  of 
the  uterine  efferent  nearby  does  not  of 
itself  indicate  the  direction  of  the  flow,  but 
the  structure  of  the  organs  distinctly  sug- 
gests that  the  flow  is  caudad,  i.e.  from  the 
uterus  toward  the  external  openings  near 
the  tail.  Were  the  entire  flow  of  the  deman- 
ian system  toward  the  uterus,  it  would 
seem  strangely  circuitous. 

While  the  fact  that  no  external  exit 
pores  have  been  discovered  in  Oncholaimium 
appendiculatum  makes  conceivable  a  flow 
from  its  enteric  vessel  and  the  moniliform 
glands  through  the  uvette  to  the  uterus,  yet 
the  structure  of  the  uvette  pore  seems  as  dis- 
tinctly adapted  to  a  flow  in  the  opposite 


438 


DISEASE   OF   ONCHOLA1MS 


direction,  i.e.  caudad,  in  this  species  as  in  the  others.  Moreover  a  different 
explanation  of  this  exceptional  case  seems  more  plausible,  namely,  that  in 
0.  appendiculatum  the  demanian  organs  are  in  a  deteriorated  condition.  The 
fact  that  this  species  is  the  only  one  that  almost  invariably  presents  disease 
in  the  posterior  extremity  of  the  adult  females  may  harmonize  with  the 
supposition  that  the  demanian  system  of  this  species  is  in  a  deteriorating 
and  perhaps  useless  condition.  The  nonconsecutiveness  of  the  posterior 
cells  of  the  moniliform  glands  in  0.  appendiculatum,  and  the  appearance 
of  crystals  on  the  outer  surface  of  the  enteric  efferent,  (Fig.  3)  suggest 
decadence  in  this  anomalous  species. 

In  0.  appendiculatum  the  uvette  is  reduced  to  a  mere  ampulla;  and  is 
almost  as  greatly  reduced  in  nigrocephalatum.  In  neither  of  these  is  it  at 
all  likely  that  the  uvette  itself  could  produce  any  very  appreciable  secretion 
flowing  into  the  uterus,  and  yet  in  both  species  the  uterine  tube  is  better 
developed  (or  at  any  rate  more  obvious)  than  it  is,  for  instance,  in  pristiurus, 
where  the  uvette  is  strongly  developed. 

Uritis.  It  is  interesting  that  the  females  of  a  number  of  oncholaims 
shown  to  possess  demanian  vessels  seem  unusually  subject  to  disease. 

Among  such  oncholaims,  allusion  is  made  to  the  following  typical  cases: 


Name 

Location 

Lesions 

Regeneration 

? 

Woods  Hole.  Mass.. 
U.  S.  A. 

"tailless" 

Undoubtedly  healed 
over 

0.  appendiculatum 

Woods  Hole,  Mass. 

From  tail  end  to  half 
of  nema  necrotic 

No  signs  of  regenera- 
tion 

M,  pristiurus 

Woods  Hole,  Mass. 

Tail  end  gone;   no 
anal  opening;  no 
spinneret 

Merely  healed  over; 
no  openings 

A.  fuscus 

1.  Cape  Cod,  Mass. 
2.  Miss  E.  Horsman 
Univ.  College  of 
Wales 

Former  uritis  (?) 
Former  uritis  (?) 

Terminus  regener- 
ated; no  spinneret 

New  Oncholaim 

Florida,  U.  S.  A. 

Former  uritis  (?) 

Imperfect  spinneret 
and  anal  opening 
regenerated 

An  interesting  morphological  problem  is  thus  disclosed.  As  the  table 
indicates,  one  not  infrequently  finds  oncholaims,  especially  females,  with 
highly  peculiar  caudal  extremities, — sometimes  without  spinneret  or  anus, 
sometimes  with  these  organs  present  but  apparently  abortive,  or  at  least 
peculiar  in  form, — abnormalities  probably  due  to  specific  disease.  Ap- 
parently the  disease  is  sometimes  combated  by  the  nemic  organization,  so  that 
the  posterior  end  of  the  nema  heals  over,  and  in  some  cases  it  seems  as  if  a  new 
anus  is  formed,  and  possibly  even  a  new  spinneret !  Just  how  this  occurs  is 
not  yet  clear,*but  I  have  seen  both  deformed  anal  openings  and  deformed 
spinnerets  of  female  oncholaims  that  appeared  to  give  evidence  of  having 
been  imperfectly  regenerated  after  some  accident,  or,  more  likely,  after  uritis. 


*  Regeneration  seems  to  be  uncommon  in  nemas. 

Additional  articles  consulted— see  zur  Strassen's  bibliographic  list,  1896. 


METONCHOLAIMUS  PRISTIURUS  (ZUR  STRASSEN) 

A  Nema  Suitable  for  Use  in  Laboratory  Courses  in  Zoology1 

BY  N.  A.  COBB 
CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XXV2 

Zur  Strassen,  who  first  proposed  the  species  Metoncholaimus  pristiu- 
rus,  alluded  for  the  most  part  only  to  the  organs  whose  forms  served 
to  distinguish  it  from  its  nearest  allies  among  the  oncholaims.  The 
present  attempt  at  a  more  complete  understanding  of  its  morphology 
adds  to  our  knowledge  in  a  number  of  ways,  especially  with  regard  to 
the  remarkable  demanian  system. 

At  the  same  time  the  text  and  figures  have  been  prepared  with  par- 
ticular reference  to  requests  of  school,  college  and  university  instruc- 
tors in  invertebrate  zoology,  a  course  suggested  by  the  fact  that  this 
species  has  been  used  with  some  promise  of  success  in  the  invertebrate 
courses  of  a  considerable  number  of  universities. 

Unfortunately  few  if  any  zoological  textbooks  treat  nemas  ade- 
quately. It  is  believed  that  any  progressive  and  well  equipped  in- 
structor who  will  study  carefully  the  following  descriptions,  with  the  aid 
of  good  living  as  well  as  preserved  specimens,  will  find  himself  all  the 
better  equipped  to  instruct  students  concerning  the  morphology  of 
the  important  nemic  phylum. 

METONCHOLAIMUS  PRISTIURUS  (Zur  Strassen) 
[Meta,  changed;  Oncholaimus,  tooth  (in  the)  throat] 

FEMALE.    Fig.  1. 

The  cuticle  and  the  body  wall.         olii "/"  i.i \A i.s o.z*  5-6mm 

The  contour  of  the  nema  is  plain.  The  thin,  transparent,  colorless,  nearly 
naked  cuticle,  72,  96,  about  one  micron  thick,  is  traversed  by  plain  transverse 
striae;  but  these  are  very  difficult  of  resolution  except  with  high  powers  of  the 
microscope  used  skillfully  under  favorable  conditions, — ordinarily  they  will 

1  Through  the  much  appreciated  courtesy  of  the  United  States  Bureau  of  Fisheries  a 
considerable  part  of  these  investigations  was  carried  out  at  its  Laboratories  at  Woods 
Hole,  Mass.  Received  May  18, 1932. 

2 Reprinted  from  the  JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES,  Vol.  22, 
No.  12,  June  19,  1932. 

Warerly  Press,  Inc.,  Baltimore,  Maryland,  December,  1932. 


440      JOUKNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES      VOL.  22,  NO.  12 

not  be  seen.  These  striae  are  not  altered  on  the  lateral  fields;  there  are  no 
longitudinal  wings.  The  subcuticle,  99,  usually  contains  multitudinous 
pebbly, — i.e.  roundish  or  slightly  elongate, — yellowish  pigment  granules,  34, 
82,  95,  one  to  two  microns  across,  "paved"  in  longitudinal  bands  of  variable 
width; — two  broad  lateral  bands,  one  on  each  side  of  the  body,  about  one- 
third  as  wide  as  the  nema  and  having  narrower  submedian  bands  on  each  side; 
and  three  narrow  ventral  bands  as  well  as  even  narrower  dorsal  bands.  These 
bands  are  better  seen  after  staining  over  night  in  seawater-methylene-blue, 
which  may  not  only  stain  them  but  bring  out  the  fact  that  the  granules  along 
the  edges  of  the  two  main  lateral  bands  are  of  a  somewhat  different  nature 
from  the  rest.  Longitudinal  striations  in  the  subcuticle,  clue  to  the  attach- 
ment of  the  musculature,  4,  16,  77,  are  faintly  visible  at  high  magnification  in 
most  regions  of  the  body,  especially  the  more  translucent  parts.  The  body 
wall,  including  the  cuticle,  is  about  six  microns  thick. 

Ten  widely  spreading  cephalic  setae,  26,  are  arranged  on  the  lateral  surface 
of  the  lip  region  in  the  usual  way,  i.e.  a  pair  on  each  submedian  line  and  one  on 
each  lateral  line;  the  longest  of  these  are  one-fourth  as  long  as  the  correspond- 
ing portion  of  the  head  is  wide,  the  shorter  member  of  each  submedian  pair 
being  about  three-fourths  as  long  as  the  longer.  The  members  of  the  sub- 
median  pairs  grow  so  close  together  as  sometimes  to  appear  as  one.  These 
subcylindroid  setae  are  nearly  straight  and  are  blunt  at  the  end,  where  they 
seem  more  or  less  open,  not  closed,  indicating,  probably,  that  they  may  also 
be  connected  with  some  sense  in  addition  to  that  of  touch.  There  are  a  few 
scattered  subcephalic  setae  near  the  head,  of  nearly  the  same  length  (ten  to 
twelve  microns)  as  the  cephalic  setae,  but  more  slender.  On  the  neck  and  on 
the  body  there  are  also  a  few  scattered  setae, — very  inconspicuous  and  seldom 
seen.  There  are  also  a  few  very  short,  very  inconspicuous  setae  on  the  tail, 
especially  toward  its  extremity  and  on  the  spinneret,  24,  74.  There  are  no 
cuticular  pores. 

The  neck  and  head.  The  head  and  neck  occupy  the  anterior  11  to  13  per 
cent  of  the  body,  i.e.  the  part  in  front  of  the  prominent  constriction,  13,  be- 
tween the  nearly  colorless  oesophagus,  12,  36,  and  the  darker  intestine,  83,  94. 
The  slightly  conoid  neck  ends  in  a  subtruncate  continuous  head,  the  frontal 
mouth  opening  in  which  is  not  depressed.  In  front  the  pharynx,  31,  48,  57, 
is  arched  over  by  the  six  distinct  and  separate,  flat  and  thin,  fairly  well 
developed,  mobile  lips,  28,  49,  which  are  not  set  off  by  constriction  or  in  any 
other  way.  As  a  rule  the  lips  are  not  readily  counted  except  when  seen  from 
in  front.  Toward  the  margin  of  the  head  there  is  a  circlet  of  six,  innervated, 
very  minute  and  inconspicuous,  forward-facing  sensory  papillae,  29,  45,  one  on 
each  lip.  This  circlet  is  about  two-thirds  as  wide  as  the  front  of  the  head. 
These  papillae  also  are  rather  difficult  to  see  except  from  in  front,  45.  The 
rather  simple  subregular  pharynx,  31,  35,  48,  57,  about  forty  by  twenty-three 
microns,  is  somewhat  cylindroid  anteriorly  and  vaguely  conoid  posteriorly. 
The  posterior  "chamber,"  35,  sixteen  by  nine  microns,  supports  the  three 
acute  onchia,  25,  33,  53,  the  forward  pointing  projection  of  the  largest  of  which 
is  very  readily  seen.  Taken  as  a  whole  the  pharyngeal  cavity  might  be 
described  as  somewhat  convex-conoid.  Its  refractive,  cuticularized  wall  is 
nearly  two  microns  thick. 

Its  armature  consists  of  three  unequal,  conoid,  perforated,  pointed  onchia, 
one  dorsal,  25,  two  ventrally  submedian,  33,  53.  Of  these  the  grooved  left 
ventral  submedian,  27,  53,  is  much  the  largest,  and  reaches  two-thirds  the  dis- 
tance to  the  lips.  The  other  two,  e.g.  33,  25,  nearly  equal  in  size,  reach  only 
about  halfway  to  the  lips.  Each  onchium  is  the  outlet  of  a  branched  and 


JUNE  19,  1932 


COBB:  METONCHOLAIMUS  PRISTIURUS 


441 


ndittt       .parsed  dint,  % 
mcsmn 
cnfmt  • 


Fig.  1— Living 
9  M.  pristiurus. 
Drawing,  from 
favorable  speci- 
men s, — m  o  d  i  fi  e  d 
from  examination 
of  intra-vitam 

methyl  blue 
staining,  and,  to  a 
very  slight  extent, 
of  carmine  stain- 
ing. Two  views  of 
the  same  head,  in 
glycerine,  are 

shown.  X  750. 
The  abbreviations 
are  self-explana- 
tory;—e.g.,  "pars 
ext  cl  int,"— ex- 

.•..:.v...-/.,...^*'-~  —-        ternal    portion    of 

'•-dM69  intestinal  cell.     Food  occurs  in  the  intestine 
OT?7/from  92  to  101.    Most  of  the  features  drawn 
,  can  be  seen  in  good  specimens  with  a  4  mm^ 
objective;  some,  however,  require  a  .good _2 or 
'^3    mm.      mmersion   objective.     Cuticulan* 
mnarts    eg     of  the  head,   may  be  favorably 
-•      7       vfewe'd   in'5-10%  KOH  solution.    Specimens 
•'UtslmeM  jSen  and  instantly  treated  with  acetic  ac,d 
'  methylene  green  are  useful. 


mcsmioo 
.dord  MIDI 
dintbhfnv 


442      JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES      VOL.  22,  NO.  12 

much  elongated  unicellular  salivary  gland,  e.g.  43,  and  dot  gl  sal,  located 
along  the  corresponding  sector  of  the  oesophagus  and  reaching  back  even  to 
near  the  base  of  the  neck,  where  the  corresponding  three  nuclei,  41,  may  be 
seen,  about  one  body-width  in  front  of  the  prominent  constriction,  13,  sepa- 
rating the  oesophagus  from  the  intestine.  Each  gland  empties  through  a 
perforation,  27,  in  the  corresponding  onchium,  by  means  of  an  inconspicuous 
ampulla  and  a  very  fine  duct, — about  one  micron  across.  The  distribution  of 
the  salivary  glands  among  the  radial  contractile  fibers  of  the  oesophagus  may 
be  indicated  by  the  granules,  one  micron  or  less  in  diameter,  to  be  seen  in 
various  parts  of  the  glands,  e.g.  at  dct  gl  sal.  In  favorable  specimens  the  ducts 
of  these  glands,  when  filled  with  this  granular  secretion,  can  be  followed 
throughout  the  length  of  the  oesophagus,  and  the  glands  are  then  seen  to  have 
numerous  short  lateral  branches,  (see  from  43  forward).  The  much  larger, 
though  inconspicuous  pigment  granules  of  the  oesophagus  are  scattered  through- 
out the  organ. 

The  external  amphids,  32,  51, — one  on  each  side  of  the  head, — are  somewhat 
escutcheon  shaped,  being  symmetrical  only  to  a  longitudinal  line,  and  are 
longer  transversely  than  longitudinally.  The  anterior  border  of  each  amphid 
is  removed  from  the  anterior  extremity  of  the  nema  a  distance  about  equal  to 
the  radius  of  the  head.  They  are  much  more  obvious  if  looked  at  dorso-ven- 
trally,  when  they  are  distinctly  seen  to  be  two  pocket-like  entrances  to  internal 
sensory  organs,  the  internal  amphids,  located  laterad  in  the  back  part  of  the 
head.  Each  of  the  external  amphids  is  about  one-fourth  as  wide  as  the  corre- 
sponding portion  of  the  head  and  about  two-thirds  as  long  as  it  is  wide.  Each 
outer  amphid  connects  with  a  sensilla,  54,  or  receptor,  close  behind,  by  means 
of  an  exceedingly  narrow  and  very  short  (two  and  a  half  microns)  but  strongly 
refractive,  duct,  shown  in  the  figure.  The  sensilla  is  one-fifth  as  wide  as  the 
head  and  lies  opposite  the  basal  part  of  the  pharynx  and  is  connected  back- 
ward with  the  central  nervous  system  by  a  lateral  nerve,  55,  just  beneath  the 
body  wall.  The  details  of  the  sensilla,  54,  are  usually  difficult  to  see  except 
when  specially  stained.  The  amphids  are  held  to  be  chemical  sense  organs. 

The  oesophagus,  12,  36,  is  cylindroid,  enlarging  very  slightly  posteriorly; 
behind  the  pharynx  it  is  three-fifths,  at  the  nerve-ring  one-half,  and  finally 
two-thirds  as  wide  as  the  corresponding  portion  of  the  neck.  The  refractive 
membranous  "triquetrous"  lining  of  the  eosophagus,  mainly  about  one  micron 
thick,  but  two  microns  in  the  axial  parts,  is  a  distinct  feature  throughout  the 
organ,  and  finds  main  optical  expression  in  what  appear  as  two  or  three  closely 
approximated  refractive,  often  slightly  sinuous,  axial  elements,  and,  in  the 
ordinary  closed  condition  of  the  oesophagus,  seeming  to  occupy  about  one- 
eighth  of  its  width.  The  radial  musculature  of  the  eosophagus,  to  be  seen 
throughout  its  length,  consists  of  fine  strands  and  is  accompanied  by  only  a 
slight  amount  of  yellowish  granular  matter.  There  are  no  cuticularized 
valves  in  the  oesophagus. 

The  intestine.  The  intestine,  83,  94,  which  becomes  at  once  two-thirds  as 
wide  as  the  body,  is  thick-walled  and  is  composed,  as  is  usual  in  nemas,  of  a 
single  layer  of  cells,  69  and  vicinity,  here  of  such  a  size  that  about  twelve  are 
required  to  complete  the  circumference.  The  walls  of  the  cells  are  only 
faintly  visible  except  sometimes  in  the  outer  colorless  part,  1,  76.  Usually  the 
lumen  of  the  intestine,  (see  just  behind  cardia,  14)  can  be  seen  only  faintly, 
since  the  lining  of  the  intestine  is  not  refractive.  As  the  nema  bends  back 
and  forth,  the  food  content  of  the  intestine,  e.g.  at  92,  may  be  seen  to  move 
backward  and  forward  in  the  lumen.  This  nema  appears  to  swallow  mud 


JUNE  19,  1932          COBB:  METONCHOLAIMUS  PRISTIURUS  443 

rather  indiscriminately,  and  to  extract  its  nutriment  from  a  variety  of  organic 
material  contained  in  the  mud.  Large  quantities  of  this  food  material  in  the 
intestine  may  interfere  with  microscopic  examination;  hence  the  advisability 
of  keeping  the  nemas  in  clean  cool  seawater  for  a  day  or  two  before  examina- 
tion. The  cardiac  collum,  or  constriction,  13,  between  the  oesophagus  and 
intestine,  is  about  two-fifths  as  wide  as  the  base  of  the  neck,  making  a  very 
obvious  demarcation  between  the  oesophagus  and  the  intestine.  There  is  a 
conoid  cardia,  14,  about  two-fifths  as  wide  as  the  base  of  the  neck;  this  is  the 
very  short  extension  of  the  oesophagus  into  the  intestine,  and  is  composed  of 
numerous  smaller  cells  of  a  distinct  kind,  having  to  do,  among  other  things, 
with  the  prevention  of  regurgitation.  Though  small,  the  cardia  is  a  very 
important  part  of  the  alimentary  canal.  The  outer  portion  of  the  intestine, 
1,  76,  is  usually  more  or  less  destitute  of  granules,  but  the  inner  and  greater 
portion  of  each  intestinal  cell  contains  globular  yellowish  granules,  69,  of 
variable  size,  the  largest  of  which  are  about  three  microns  in  diameter,  and 
the  smallest  less  than  one  micron.  These  granules  are  varied  and  numerous, 
sometimes  are  even  packed  close  together,  and  may  be  so  arranged  in  the  cells 
as  to  give  rise  to  a  faint,  or  sometimes  a  quite  distinct,  tessellated  effect. 

The  intestine  is  made  up  of  cells  of  different  kinds, — discharging  different 
functions.  One  of  these  various  kinds  is  readily  made  out,  especially  with  the 
aid  of  polarized  light,  namely  the  cells,  as  many  as  one  hundred  in  number  or 
even  more,  containing  the  exceedingly  minute  Urefringent  granules.  These 
cells,  15,  81,  98,  when  examined  by  ordinary  transmitted  light,  present  a 
finer  texture  internally,  and  usually  are  more  distinctly  yellowish.  If  a  suit- 
able specimen  be  allowed  to  remain  in  a  concentrated  solution  of  seawater- 
methylene-blue  a  few  minutes,  a  differential  staining  of  the  "birefringent" 
cells  will  often  occur,  but  the  effect  does  not  last.  The  "birefringent"  cells  are 
everywhere  less  numerous  than  those  that  do  not  contain  birefringents,  and 
there  are  none  of  them  at  all  in  the  posterior  part  of  the  intestine.  We  may 
therefore  speak  of  two  distinct  intestinal  regions,  one  fore,  one  aft.  The 
"birefringent"  cells  occur  in  early  ovic  embryos. 

The  rather  prominent  short  rectum,  19,  the  rear  part  of  the  intestine,  is 
somewhat  cuticularized,  and  is  about  as  long  as  the  anal  body  diameter;  from 
the  somewhat  depressed  anus,  70,  it  extends  inward  and  forward  at  an  angle  of 
about  forty-five  degrees.  Its  structure  in  the  female  differs  somewhat  from 
that  of  the  male,  which  appears  "helical."  The  anterior  and  posterior  lips  of 
the  anus  are  of  about  equal  size.  Small  inconspicuous  somewhat  pear-shaped 
unicellular  anal  glands  can  sometimes  be  seen,  lying  alongside  the  rectum  with 
their  narrowed  necks  directed  toward  the  anus. 

Tail  and  spinneret.  The  slightly  arcuate  tail  is  first  conoid,  then  cylindroid 
in  the  posterior  fourth,  where  it  ends  in  a  somewhat  blunt,  almost  impercep- 
tibly swollen,  rounded  spinneret,  73,  armed  only  with  three  exceedingly  incon- 
spicuous setae,  two  ventrally  submedian,  74,  and  a  dorsal  one,  24.  Though 
insignificant  in  appearance  these  sensory  setae  are  important.  The  very 
nearly  symmetrical  spinneret  displays  internally  the  three  very  slightly 
swollen  ampullae  of  the  three  caudal  glands,  23.  The  spinneret  valve,  or  plug,  75, 
four  microns  across,  almost  at  the  very  end  of  the  tail,  stains  green  with 
methyl  blue  ("intra  vitam")  while  other  nearby  parts  stain  blue.  This  impor- 
tant valve  is  hemispherical  posteriorly  and  tapers  anteriorly  to  a  fine  contractile 
element,  shown  white  in  the  drawing,  fastened  in  the  midst  of  the  three  ampul- 
lae (23).  It  is  by  the  contraction  of  this  minute  fiber  that  the  plug  or  valve  is 
pulled  away  from  its  seat,  so  as  to  permit  the  sticky,  non-water  soluble, 


444      JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES      VOL.  22,  NO.  12 


vglmal 

/JffltSt'" 


cement-like  secretion  of  the  three  caudal  glands  to  pour  outward  to  be  used  in 
temporarily  cementing  the  nema  by  the  tail  to  the  substratum  in  a  versatile 
manner.  The  spinneret  and  associated  glands  are  of  vital  importance  to 
aquatic  nemas;  and  this  apparatus  is  all  but  universal  among  them.  The 
three  elongated  ellipsoidal  caudal  glands,  84,  88,  90, — the  remotest  of  them 
ten  body-diameters  in  front  of  the  anus, — are  scattered  in  a  loose  tandem  in 
the  ventral  part  of  the  body  cavity.  Their  ducts,  18,  86,  leading  to  the  spin- 
neret, can  be  distinctly  seen  under  some  circumstances.  Most  of  the  caudal 
setae  on  the  female  are  reduced  and  inconspicuous. 

It  is  the  sticky  nature  of  the  secretion  of  the  caudal  glands  that  enables 
these  nemas  to  ensconce  themselves  so  securely  in  the  midst  of  the  elements  of 
the  mud  in  which  they  live.  By  its  aid  they  attach  themselves  to  the  sub- 
stratum, especially  in  times  of  danger,  and  to  each  other.  By  means  of  this 
cement,  they  bind  themselves  together  with  mud  etc.  in  almost  inextricable 
tangles. 

The  two  very  thin  ribbon- 
like  lateral  cords,  3,  93,  of 
Metoncholaimus  pristiurus, 
one  on  each  side,  imme- 
diately under  the  cuticle, 
are  about  half  as  wide  as 
the  body,  each  cord  consist- 
ing of  three  regions, — a  me- 
dian region  composed  of  a 
single  broad  row  of  quadrate 
cells,  and  a  row,  less  than 
half  as  wide,  on  each  side  of 
it.  In  the  anterior  part  of 
the  body  the  quadrate  cells 
are  usually  a  little  longer 
than  they  are  broad,  in  the 
posterior  part  a  little  shorter 
than  broad.  As  stated, 
these  median  cells  are 
flanked  by  two  much  nar- 
rower longitudinal  series  of 
cells,  having  the  same  gen- 
eral composition,  i.e.  a  very 
fine  protoplasmic  network 
(meshes  two  microns  to 
five  microns)  in  the  inter- 
sections of  which  are  roundish  or  somewhat  ellipsoidal  yellowish  granules, 
usually  not  equidiametral.  Even  without  staining,  there  are  also  to  be 
seen,  at  least  in  each  of  the  cells  composing  the  central  row  of  the  lateral 
cord,  faint  indications  of  a  nucleus;  these  indications  in  the  living  nema  con- 
sist in  an  almost  entire  absence  of  the  reticulation  which  is  to  be  found  else- 
where in  the  cell.  These  cells  of  the  lateral  cord  are  necessarily  very  flat; 
that  is  to  say,  their  depth  (radially  to  the  nema)  is  much  less  than  their  diam- 
eter in  either  of  the  other  two  directions, — i.e.  longitudinally  to  the  nema  or 
tangentially.  The  division  line  between  the  central  row  of  cells  and  the 
narrower  ones  on  the  margin  is  an  almost  invisible,  very  thin,  somewhat 
indirect  cell-wall  line.  Around  the  outer  margins  of  the  two  outer  rows  of 
cells  the  granules  are  slightly  differentiated  from  the  other  granules;  so  that  in 


IB mem 
n  jar  Am 


&  rectum 


u 


Fig.  2— Tail  of  fe- 
male M.  pristiurus,  X 
325;  showing  the  mi- 
nute but  important 
spinneret  valve,  vlv 
spn,  and  the  muscular 
strand  leading  from  it 
into  the  midst  of  the 
3  ampullae  of  the 
caudal  glands;  shown 
light  in  the  midst  of 
the  spinneret.  Note 
the  pylorus  at  pylor. 


.spnn 


spn  75 


JUNE  19,  1932          COBB:  METONCHOLAIMUS  PRISTIURUS  445 

seawater-methylene-blue  the  subcuticular  pigment  granules  on  the  borders  of 
the  longitudinal  bands,  already  described  in  connection  with  the  cuticle,  mav 
stain  green  at  a  time  when  the  rest  of  the  granules  stain  blue.  This  appear- 
ance is  similar  to  what  is  now  being  described  for  the  unstained  nema;  so  that 
the  structure  of  the  lateral  cords  is  now  shown  to  be  in  harmony  with  that  of 
the  longitudinal  bands  of  subcuticular  pigment.  In  other  words,  the  arrange- 
ment of  the  pigment  granules  of  the  cuticle  is  doubtless  in  some  way  correlated 
with  the  arrangement  of  the  cells  in  the  lateral  cords  beneath.  The  proto- 
plasmic network  in  the  cells  of  the  lateral  cords  is  considerably  finer  than  the 
protoplasmic  network  in  the  outer  part  of  the  cells  composing  the  intestine, 
but  nevertheless,  has  the  same  general  appearance.  The  lacunae  among  the 
strands  of  the  network  are  of  variable  size,  more  or  less  equidiametral, 
though  never  exactly  so; — polygonal,  but  not  regularly  so.  The  lateral  cords 
are  wellsprings  of  the  cuticle. 

The  granules  of  the  subcuticle,  34,  82,  95,  differ  from  the  yellowish  gran- 
ules contained  in  the  network  of  the  cells  of  the  lateral  cord;  in  the  specimen 
under  examination  the  granules  in  the  subcuticle  (a  little  under  one  micron) 
are  more  nearly  colorless  and  are  round,  whereas  those  in  the  lateral  cord  are 
yellowish,  and  somewhat  irregular  in  size  and  form. 

Renette  and  excretory  pore.  The  excretory  pore,  58,  is  located  about  one- 
fourth  the  distance  to  the  nerve-ring  on  the  ventral  side  of  the  neck.  The 
nucleated  single  renette  cell,  68,  about  four  body-widths  behind  the  neck,  is  a 
fusiform,  granular,  ventrad  cell,  about  twice  as  long  as  wide,  and  nearly  two- 
thirds  as  long  as  the  corresponding  body  diameter;  the  renette  duct,  60,  67, 
leads  from  it,  somewhat  meanderingly,  forward  to  the  excretory  pore,  and  is 
readily  seen,  as  a  rule, — or  at  least  some  of  it  is.  It  is  a  slender  tube  about 
one-twentieth  as  wide  as  the  neck  and  ends  anteriorly  in  a  small  ellipsoidal 
ampulla,  near  58,  nearly  one-third  as  long  as  the  neck  is  wide,  emptying 
outward  through  the  ventral  excretory  pore  in  the  cuticle  by  means  of  an  ex- 
ceedingly narrow  duct  only  three  to  four  microns  long.  The  excretory  secre- 
tion of  this  gland,  as  seen  in  its  duct,  and  ampulla,  is  granular,  the  uniform, 
spherical,  colorless  granules  being  about  one  micron  in  diameter.  This 
entire  apparatus,  the  renette,  is  regarded  as  excretory  in  function. 

Nervous  system.  An  important  part  of  the  central  nervous  system  is  the 
nerve-ring,  38,  about  ten  microns  wide,  surrounding  the  oesophagus  somewhat 
obliquely  in  front  of  the  middle.  It  consists  of  a  compact  network,  or  skein, 
of  exceedingly  fine  nerve  fibers.  Before  and  behind  the  nerve-ring  are  scores 
of  distinct  nucleated  ganglion  cells,  11,  56,  etc.,  mostly  bipolar,  those  in  frort 
being  arranged  in  eight  obscure  longitudinal  groups, — two  lateral,  one  ventral, 
one  dorsal,  and  four  submedian.  The  ganglion  cells  are  variously  connected 
with  each  other  and  with  the  nerve-ring.  Placing  the  nema  over  night  in 
seawater-methyl-blue  discloses  some  of  the  elements  of  the  ventral  nerve 
leading  from  the  nerve-ring  along  the  ventral  line  to  the  tail.  Usually  about 
128  fusiform  elements  in  the  ventral  series  may  be  disclosed  (stained  blue) 
in  this  way.  These  can  be  proved  to  be  connected  with  each  other.  The 
same  treatment  is  likely  also  to  reveal  the  nerve  elements  entering  the  bases 
of  setae,  and  papillae,  especially  in  the  tail  of  the  male.  See  Fig.  4. 

Female  organs.  From  the  slightly  elevated  vulva,  7,  which  is  a  transverse 
ventral  slit  of  moderate  size,  the  medium  sized  vagina  leads  inward  and 
slightly  forward  about  halfway  across  the  body;  the  vagina  is  somewhat 
cuticularized  and  is  accompanied  by  small  and  very  inconspicuous  vaginal 
glands,  9,  fore  and  aft.  About  two  dozen  radiating  muscles,  6,  occur  around  the 


446      JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES      VOL.  22,  NO.  12 

vulva,  together  with  an  associated  complicated  nerve  plexus.  This  muscula- 
ture is  least  developed  behind  the  vulva. 

The  straight  uterus,  30,  8,  extends  forward,  and  is  of  such  capacity  as  to 
accommodate  a  maximum  of  about  forty  eggs,  10,  39,  (i.e.,  many  more  than 
shown  in  this  drawing)  arranged  approximately  single  file,— although  this 
large  number  of  eggs  is  rarely  seen  except  toward  autumn.  Under  such  cir- 
cumstances the  oblate  eggs,  seeming  to  nearly  fill  the  body  cavity  in  this  region. 
are  more  or  less  ellipsoidal  in  contour  and  half  a  body-width  long,  and  twice 
as  wide  as  long.  When  deposited,  or  when  not  crowded  in  the  uterus,  the 
eggs  are  ellipsoidal  and  longer  than  wide.  The  shells  of  the  eggs,  one  and  a 
half  microns  thick,  are  smooth,  and  the  eggs  are  deposited  before  segmentation 
begins.  Naturally,  the  length  of  the  uterus  varies  according  to  the  number 
of  eggs  it  contains. 

The  broad  reflexed  ovary  appears  more  or  less  cylindroid,  and  when  there 
are,  say,  a  dozen  eggs  in  the  uterus,  the  terminus  of  the  ovary,  59,  lies  about 
halfway  back  to  the  vulva.  The  narrow  oviduct,  46,  52,  leading  from  the 
front  end  of  the  ovary  back  to  the  uterus,  is  usually  nearly  invisible,  but  when 
a  ripe  ovum,  50,  having  passed  round  the  bend  (flexure)  near  46,  is  being 
forced  backward  through  it  from  the  front  part  of  the  ovary  back  to  the 
uterus,  its  presence  is  obvious.  It  is  faintly  visible  at  52.  The  ova  are 
fertilized  on  first  reaching  the  uterus,  and  soon  after  this  it  is  not  very  un- 
common to  witness  the  early  stages  of  the  formation  (mit,  Fig.  1)  of  the  polar 
bodies, — which  appear  later  as  small  spherical  bodies  just  under  the  eggshell. 
A  small  collection  of  sperms  is  seen  in  the  spermathecal  region  at  61. 

The  demanian  system.  In  the  adult  female  of  Metoncholaimus  pristiurus 
there  is  a  complicated  double  system  of  efferent  tubes,  the  demanian  vessels, 
connecting,  first,  with  the  posterior  part  of  the  intestine  through  an  osmosium, 
87,  and  second,  with  the  posterior  end  of  the  uterus  by  means  of  a  very  long 
slender  efferent  duct,  79,  85.  These  two  efferents  join  at  a  conspicuous 
thirty-two-merous,  special  glandular  gateway, — the  uvette,  40, — and  empty, 
by  way  of  the  uvette  pore,  62,  thence  backward  and  outward  through  two 
separate  narrow  lateral  ducts,  42,  having  attached  to  them,  along  their  outer 
sides,  relatively  large  and  long  conspicuous  moniliform  affluent  glands,  64, 
seventeen  microns  wide,  each  consisting  usually  of  sixy-four  somewhat 
discoid  elements,  66, — occasionally  double  (?)  this  number.  These  discoid 
cells  of  the  two  moniliform  glands  are  three  microns  thick  and  packed  with 
granules  of  the  order  of  one  micron;  the  flat  ducts,  along  the  inside  of  the 
moniliform  glands,  lead  to  two  exit  pores,  the  right  hand  one  shown  at  17,  five 
by  seven  microns,  laterad  in  the  body  wall  one-half  tail-length  in  front  of 
the  anus.  However,  the  caudad  elements  of  the  moniliform  glands  are 
"pyriform,"  as  shown  in  the  illustration,— not  discoid.  The  demanian  vessels 
elaborate  a  copious,  elastic,  sticky,  non-water-soluble,  nearly  colorless  secretion, 
possibly  utilized  during  agglomeration  and  copulation,  and  also  mayhap  to 
protect  and  preserve  the  batches  of  eggs  after  deposition  and  during  seg- 
mentation. 

The  uvette,  40,  is  a  very  striking  organ  consisting  of  thirty-two  concen- 
trically arranged,  highly  refractive,  flask-shaped,  glandular  elements,  all 
concentric  about  a  single  minute  central  pore,  62,  leading  into  the  large  duct 
passing  backward  and  dividing  to  form  the  two  lateral  efferent  ducts  each 
accompanied  by  a  sixty-four-fold  moniliform  gland,  as  already  described. 
The  connection  of  the  intestine  with  the  demanian  system  at  the  osmosium 
is  not  an  open  one;  the  nature  of  the  connection  with  the  uterus,  however, 
appears  less  certain. 


JUNE  19,  1932          COBB:  METONCHOLAIMUS  PRISTIURUS  447 

The  osmosium,  87,  of  the  enteric  efferent  is  located  about  one-third  the 
distance  from  the  anus  to  the  vulva,  and  may  usually  be  seen  on  the  dorsal 
side  of  the  intestine, — being  mainly  visible  on  account  of  the  somewhat 
greater  transparency  of  its  tissues.  The  narrow  uterine  efferent  duct,  ut. 
eff.,  79,  85,  is  very  difficult  to  follow  throughout  its  length,  and  usually  can  be 
seen  only  in  specially  favorable  specimens.  Its  connection  with  the  posterior 
end  of  the  uterus  is  sometimes  easy  to  see, — near  30.  Its  connection  with  the 
uvette  is  also  nearly  always  easy  to  see,  and  it  may  be  followed  thence  for- 
ward a  short  distance,  but  to  trace  it  far  is  usually  a  matter  of  some  difficulty. 

The  thirty-two  flask-shaped  elements  of  the  uvette  have  their  necks  con- 
centrated at  the  pore.  The  wall  of  the  uterine  duct,  as  previously  described, 
spreads  out  over  the  uvette,  and  beneath  it  the  thirty-two  elements  form  a 
craterlike  affair  leading  to  the  uvette  pore.  This  pore  opens  into  the  some- 
what duplex  (but  really  monoluminal)  corridor  of  the  caudad  part  of  the 
intestinal  efferent.  This  latter  efferent  may  show  signs  of  forking  at  a  dis- 
tance in  front  of  the  uvette  about  equal  to  the  corresponding  body  diameter, 
but  is  seldom,  if  ever,  really  bifurcate  until  behind  the  uvette. 

Or, — following  the  demanian  system  from  the  rear  toward  the  uvette: — Where 
the  moniliform  glands  approach  the  uvette,  they  join  to  form  a  two-fold 
structure,  and  the  pore  of  the  uvette  is  placed  between  the  two  parts  of  this 
double  structure.  The  structure  of  the  tunic  of  the  demanian  system  opposite 
the  uvette  presents  two  sets  of  exceedingly  fine  symmetrically  arranged 
elements, — one  sloping  45°  right,  the  other  left,— which  continue  forward. 
This  "spiral"  structure  can  be  seen  throughout  the  duplex  portion  of  the 
demanian  system  now  being  described,  namely  that  portion  in  the  vicinity 
of  the  uvette. 

Sperms,  61,  are  to  be  seen  at  the  cephalad  end  of  the  uterus  i.e.,  the  sper- 
matheca,  where  the  oviduct  joins  the  uterus,  sometimes  in  a  mass  comprising 
scores  of  sperms,  each  about  one-tenth  as  wide  as  the  corresponding  portion 
of  the  body.  They  are  rather  difficult  to  see  except  when  they  are  present 
in  considerable  numbers. 

MALE.  Fig.  3. 

0.8      53       11.  «SM_  &e.  ^, 

The  spicula  and  other  male  organs,  b.a "/"  "ii ii  " '          "  iVs'  ^    -^oi 

The  tail  of  the  male  is  more  or  less  like  that  of  the  female  in  form,  but  is 
somewhat  larger,  more  arcuate,  and  far  more  flexible,  even  prehensile,  as  Fig. 
2  indicates.  It  diminishes  a  little  more  suddenly  in  size  at  the  anus,  and  is 
armed  with  special  setae  and  papillae.  The  two,  equal,  colorless,  long  and 
very  slender,  uniform  spicula,  57,  58,  seven  times  as  long  as  the  anal  body 
diameter,  are  almost  imperceptibly  cephalated  by  expansion.  They  are 
simple  and  frail  looking,  their  proximal  ends  lying  more  or  less  opposite  the 
body  axis.  A  long  slender,  duplex,  nucleated  retractor  muscle,  16,  extends 
forward  from  the  proximal  end  of  each  spiculum  to  the  body-wall  in  the  cor- 
responding subdorsal  region,  near  12;  an  antagonistic  protrusor  muscle,  of 
about  equal  size  ensheaths  each  spiculum.  The  small  inconspicuous  guber- 
naculum,  42,  lying  near  the  anus,  is  double  and  straight.  Its  two  equal  parts 
are  somewhat  frail  and  simple,  but  are  expanded  internally  so  as  to  be  visible. 
They  are  only  about  half  as  long  as  the  anal  body  diameter,  and  lie  against 
the  tips  of  the  spicula  in  such  a  way  that  their  swollen  and  more  visible 
proximal  ends,  42,  lie  nearly  opposite  the  axis  of  the  base  of  the  tail. 

There  is  a  single  inconspicuous  preanal  ventral  papilla,  22,  very  close  to  the 
anus,  21,  but  readily  seen  when  searched  for.  There  are  about  ten  small 


448      JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES      VOL.  22,  NO.  12 


JESC  SOS  69 


Fig.  3 — d*  If.  prisliurus, 
from  balsam  specimens; 
stain,  acid  carmen.  Com- 
pare with  Fig.  1.  Here  the 
nuclei  are  brought  out  more 
distinctly.  The  renette  and 
caudal  glands  may  be  fol- 
lowed throughout.  Devel- 
opment of  the  sperms  can 
be  followed;  reduction  divi- 
sion is  shown  at  2.  The 
long  gland  accessory  to  the 
male  gonads  can  be  followed 
from  23  to  33.  One  of  the 
exceedingly  slender  spicula 
is  shown,  together  with  its 
long  duplex,  nucleated  re- 
tractor muscle.  The  oblique 
copulatory  muscles  of  the 
male  extend  forward  to  near 
the  vicinity  of  74.  The 
minute  but  important  spin- 
neret valve  is  shown  at  20. 
The  oesophageal  glands 
shown  at  28,  may  be  profit- 
ably compared  with  the 
larger  drawings  in  Fig.  1. 


conical  supplementary  organs,  19, 
on  the  ventral  and  subventral  pos- 
terior two-fifths  of  the  tail.  These 
are  arranged  in  a  sort  of  ventral 
row,  but  the  anterior  ones  are  more 
or  less  staggered;  they  are  somewhat 
unequally  spaced,  being  wider  apart 
posteriorly.  They  give  a  serrated 
appearance  to  the  ventral  contour  of 
the  posterior  part  of  the  tail,  hence 
the  specific  name,  pristiurus  (saw- 
tailed).  There  are  also  about  thirty 
ventrally  submedian  short  setae,  18, 
on  the  front  portion  of  the  tail, 
about  fifteen  on  each  subventral 
line.  These  two  rows  extend  forward 
to,  and  around,  the  anus,  forming 
there  a  sort  of  circlet  of  inconspic- 
uous character.  These  conical  sup- 
plements and  setae  of  the  male  are 
special  sensory  organs;  each  is  supplied  with  a 
minute  nerve  readily  demonstrable  with  seawater- 
methylene-blue  (See  Fig.  4). 

The  internal  male  organs.  The  two  slender, 
straight  testes,  7,  63,  70,  76,  of  about  equal  length, 
but  the  posterior  somewhat  the  longer,  are  out- 
stretched in  opposite  directions,  and  extend  along 
the  middle  third  of  the  body,  each  being  about 
sixteen  body-widths  long.  The  ejaculatory  duct, 
17,  59,  toward  the  anus,  is  one-fifth;  the  vas 
deferens,  14,  53,  next  farther  forward  and  set 


150 


JUNE  19,  1932 


COBB:  METOXCHOLAIMUS  PRISTIURUS 


449 


Fig.  4— Tail 
end  of  M.  pris- 
tiurus,  Male  X 


wnstrx 


off  from  the  ejaculatory  duct  by 
a  distinct  constriction,  56,  is  one- 
fourth;  and  the  testes  average 
one-fourth  to  one-half; — as  wide 
as  the  body.  There  is  a  con- 
striction  midway  in  the  vas  defer- 
ens,  37.  The  blind  end  of  the 
anterior  testis,  70,  directed  for- 
ward, is  about  two  neck  lengths 
behind  the  cardia,  while  the  blind 
end  of  the  posterior  testis,  76,  di- 
rected backward,  is  about  five 
tail-lengths  in  front  of  the  anus. 

Beginning  between  the  renette 
cell  and  the  cardia  (at  23)  there 
is  a  long,  straight,  tapering  ac- 
cessory gland,  51,  emptying  back- 
ward into  the  beginning  of  the 
vas  deferens,  i.e.,  at  the  point 
where  the  two  testes  join  it,  33.  .  ^. 

This   gland,    accessory    to    the  22 fn ''  44TCt 
gonads,    is,    no    doubt,    a    re- 
duced homologue  of  the  demanian  system  of  the  female.    A  possible  func- 
tion is  the  production  of  cement  (aseptic?)  used  in  copulation. 

The  primary  spennatocytes,  69,  near  the  blind  end  of  the  testes  are  about 
forty  microns  in  diameter.  About  twenty  of  them  would  be  required  to 
span  the  corresponding  body  diameter.  Full  grown  spennatocytes,  4,  36, 
occur  farther  along  the  testes  in  rouleaux,  and  are  two-fifths  as  wide  as 
the  body  of  the  nema  and  one-third  as  long  as  wide.  Nearly  simultaneous 
synapses  and  reduction  divisions  of  a  full  grown  sperm  are  often  in  progress  in 
one  or  the  other  testis,  2,  3,  and  the  members  of  the  resulting  quartet,  2,  of 
smaller  cells, — that  is  the  resulting  spermatids, — are  somewhat  equidiametral 
and  are  about  one-fifth  as  wide  as  the  body. 


.COP  MM 

X1000 

Fig.  5— Cross  sections  of  Metoncholaimus  pristiurus  through  the  regions  of  the 
moniliform  glands  of  the  female  and  the  spicula  of  the  male  respectively. 


450       JOURNAL  OF  THE  WASHINGTON  ACADEMY  OF  SCIENCES       VOL.  22,  NO.  12 

The  three  caudal  glands,  15,  38,  and  their  three  ducts,  as  at  40,  are  shown 
more  clearly  when  stained,  as  in  the  male  specimen  figured. 

Habitat:  Stagnant  marine  mud,  below  low  tide,  often  where  there  is  a  slight 
overgrowth  of  eelgrass;  harbor  at  Woods  Hole,  Massachusetts,  U.  S.  A.  at 
all  seasons.  It  also  occurs  in  the  Mediterranean  Sea,  near  Naples,  Italy. 
This  species  is  subject  to  autumnal  (?)  attacks  of  fungi  and  bacteria.  The 
resulting  diseases  are  of  a  very  interesting  character,  and  sometimes  give  rise 
to  necrosis  of  the  posterior  part  of  the  body.  One  of  the  common  assailant 
cyanophytes(?)  gives  rise  to  an  extensive  aigrette-like  appearance. 

Examination  of  the  living  specimens  may  very  profitably  be  supplemented 
by  examination  of  temporary  mounts  in  lactophenol,  5  per  cent  solution  of 
potassium  hydrate,  and  (broken  open)  in  acetic  acid-methylene  green,  as  well 
as  "intra-vitam"  in  seawater-methyl  blue. 


A  KEY 

TO  THE  GENERA 
OF  FREE-LIVING  NEMAS 


CONTRIBUTIONS 

TO  A  SCIENCE  OF  NEMATOLOGY 
XXVI 

BY 

N.  A.  COBB 


BALTIMORE 
1935 


A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS 

BY  N.  A.  COBB 

Division  of  Nematology,  U.  S.  Bureau  of  Plant  Industry 

Checked,  revised  and  prepared  for  the  press  by  Margaret  V.  Cobb  and  Corinne  Cooper 

CONTRIBUTIONS  TO  A  SCIENCE  OF  NEMATOLOGY  XXVI1 

PREFACE 

This  key,  which  was  built  up  and  used  by  N.  A.  Cobb  as  a  card 
catalog  during  forty  years  of  work  in  nematology,  had  been  reorgan- 
ized in  rough  manuscript  form  during  the  last  two  years  of  his  life. 
As  Miss  Cooper  and  I  had  previously  worked  with  him  on  this  draft, 
it  seemed  best  for  us  to  carry  it  to  completion.  In  essentials  and 
in  general  form  it  is  his  key,  but  we  are  responsible  both  for  cor- 
rectness of  detail  (an  appreciable  amount  of  the  detailed  work  was 
incomplete,  in  need  of  revision,  or  in  need  of  change  because  of  ad- 
dition or  omission  of  genera),  and  for  such  decisions  as  have  to  be 
made  in  getting  such  a  work  printed.  Our  aim  has  been  to  follow  his 
ideas  wherever  they  were  known  to  us,  or  where  we  could  infer  them, 
and  to  make  as  few  changes  as  possible  in  his  outline.  Nearly  a 
hundred  entries  have  been  omitted,  chiefly  his  own  new  genera 
which  it  has  not  been  possible  to  publish  in  advance  of  publication 
of  the  key.  In  some  cases  genera  have  been  dropped  as  not  being 
free-living.  Index,  glossary  and  list  of  abbreviations  have  been  added. 
The  bibliography  has  been  prepared  by  Mrs.  Rowena  R.  LeHew 
of  the  Division  of  Nematology.  The  definitions  in  the  glossary 
are  not  intended  to  settle  the  meaning  of  terms  for  other  workers 
in  the  field,  but  merely  to  indicate  the  terminology  used  in  this  key. 

A  few  details  in  the  form  of  the  key  stand  in  need  of  special  explana- 
tion. Parentheses  have  been  used  around  generic  names  in  the  key 
in  two  ways ;  one,  to  indicate  that  the  genus  is  better  placed  elsewhere 
in  the  key,  and  two,  with  an  equality  sign,  to  indicate  a  synonym  for 
the  accepted  name  of  a  genus.  An  example  of  this  second  use  is  given 
by  the  first  genus  entry  in  the  key.  The  symbols  9  for  female,  d"  for 

Received  September  20,  1934. 

1  Reprinted  from  the  Proceedings  of  the  Helminthological  Society  of  Washington, 
Vol.  II,  No.  1,  January,  1935.  Repaged  without  material  alterations. 

451 


452 


PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 


male,  and  J  for  young  or  immature  specimens  are  used  throughout  the 
key  as  a  means  of  saving  space;  "c?  only,"  for  instance,  indicates 
that  only  the  male  form  is  known.  The  %  sign  is  used  to  mean  per- 
cent of  body  length,  or,  distant  from  anterior  end,  measured  in  percent 
of  body  length. 

In  general  the  intention  has  been  to  include  all  synonyms,  together 
with  the  corresponding  accepted  generic  names.  The  case  of  Di- 
chromadora  and  Trichromadora,  Kreis  1929,  is  an  exception;  these 
designations  seemed  to  cut  across  the  accepted  classification  in  such  a 
way  as  to  make  their  inclusion  impracticable. 

Through  the  much  appreciated  courtesy  of  the  United  States  Bureau 
of  Fisheries,  a  part  of  the  work  on  the  key  had  been  carried  out  at  its 
Laboratories  at  Woods  Hole,  Mass.  Needless  to  say,  the  work  could  not 
have  been  completed  or  completion  even  attempted  by  us  without  the 
resources  and  the  expert  advice  of  the  Division  of  Nematology,  of  the 
Bureau  of  Plant  Industry,  U.  S.  Department  of  Agriculture,  within 
which  the  work  has  been  done.  Dr.  G.  Steiner  and  Dr.  J.  R.  Christie  have 
given  never-failing  aid.  Dr.  Maurice  Hall  and  Dr.  B.  Chitwood  of  the 
Division  of  Zoology  have  also  given  generously  of  their  time,  their 
knowledge  and  their  experience. 

MARGARET  V.  COBB. 

ABBREVIATIONS  USED  IN  KEY 


abs,     absent 

lab,     labial 

0      absent,  none 

am'g,     among 
alt,     alternative 

lat,     lateral 
long,     longitudinal 

+      or  more,  plus 
±      more  or  less,  somewhat,  about 

amph,     amphid 
ant,     anterior 

mand,    mandibular 
med,    median 

%      per  cent  of  body  length 
cf      male 

card,     cardiac 
caud,     caudal 

no,    number 
nr,    near 

d"  only  only  the  male  known 
9      female 

ceph,     cephalic 

oes,    oesophagus 

'  9  '     ovaries  2,  reflexed 

cerv,     cervical 

oesoph,    oesophagus 

~9~    ovaries  2.  outstretched 

circ,     circular 

onch,    onchium 

'9       ovary  1,  anterior,_reflexed 

conspic,     conspicuous 

opp,    opposite 

9  f     ovarv    1  ,    posterior,    reflexed 

constrict,     constriction 
cutic,     cuticular 
cylind,     cyUndroid 

papill,    papillae,  papilloid 
phar,    pharynx,  pharyngeal 
pharyng,    pharyngeal 

"9      ovary  1,  anterior,  outstretched 
9~    ovary  1,  posterior,  outstretched 

dents,     denticles 

post,    posterior 

Bast,    Bastian 

devel,     developed 

pres,    present 

Btitsch,    Biltschli 

diam,      diameter 

prob,    probably 

Clap,    Claparede 

exc,     except 

prs,    pairs 

Dies,    Diesing 

excret,     excretory 

reg,    region 

Ditlev,    Ditlevsen 

ext,     external 

set,    setae 

gub,     gubernaculum 
gubernac,     gubernaculum 
inconspic,     inconspicuous 
indef,     indefinite 

stri,    striae 
subceph,    subcephalio 
sublat,    sublateral 
submed,    submedian 

Duj,    Dujardin 
Ehrenb,    Ehrenberg 
Fil,    Filipjev 
Leuck,    Leuckart 

intest,     intestine 

term,    terminal 

Linst,    von  Linstow 

irreg,     irregular 
J,    young,  juvenile 

undev,    undeveloped 

Metsch,    Metschnikoff 
Micol,    Micoletzky 

junct,     junction 

Strass,    zur  Strassen 

COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  453 

GLOSSARY 

adhesion  tubes,    hollow  tube-like  setae  by  means  of  which  some  nemas  "walk"  along  a  surface 

ambulatory  setae,    setae,  sometimes  hollow  and  tube-like,  by  means  of  which  some  nemas  "walk"  along  a  surface 

amphid,    a  paired  lateral  sense  organ  the  opening  of  which  is  often  conspicuous,  near  the  anterior  end 

amphidial  opening,    the  pore  (or  larger  aperture)  through  the  cuticle  at  which  amphid  opens  exteriorly 

amphidial  pocket,    a  chamber,  outline  often  cup-shaped,  sometimes  present  just  behind  external  amphid 

ampulla,    widening  in  canal,  forming  a  reservoir 

annulated,    haying  annules 

annules,    definite  transverse  rings  of  the  cuticle 

apophysate,    having  an  apophysis 

appendicule,    a  large  single  ventral  pre-anal  supplementary  organ  which  is  extensible 

bursa,     flap-like  extensions  of  the  lateral  cuticle  of  the  tail  end  of  the  male 

calvarium,    subcuticular  cephalic  framework 

cardiac  bulb,    swelling  of  oesophageal  wall,  glandular  or  muscular,  just  anterior  to  beginning  of  intestine 

cardiac  valve,    thickening  or  complication  of  oesophageal  lining  in  cardiac  bulb,  functioning  as  a  valve 

caudal  glands,    3  cells  in  or  near  tail,  emptying  by  separate  ducts  into  a  common  ampulla  at  spinneret 

cephalated,    having  the  head  or  anterior  end  set  off  in  some  way 

cephalic  setae,    setae  of  the  second  or  "outer"  circlet  around  the  mouth 

cephaloboid,    resembling  (that  of)  the  genus  Cephalobus 

cervical,    on  the  neck 

chromadoroid,    resembling  (that  of)  the  genus  Chromadora 

cirri,    elaborate  cephalic  appendages  in  front  of  the  cephalic  setae 

cuirasse,    a  helmet-like  appearance  of  cuticle  of  bead 

cyatholaimoid,    resembling  (that  of)  the  genus  Cyatholaimus 

demanian  system,    gonenteric  system  of  vessels  connecting  intestine  and  uteri  with  each  other,  and  posteriorly 

with  the  exterior 
dentate,     bearing  teeth 

denticles,    minute  teeth  or  "prickles,"  usually  numerous 
denticulate,    bearing  denticles 

diplogastroid,    resembling  (that  of)  the  genus  Diplogaster 
dorylaimoid,    resembling  (that  of)  the  genus  Dorylaimus 

enchelid,    male  form  such  as  has  been  classified  in  the  genus  Enchelidium,  male  of  Symplocostoma  group 
eurystomoid,    resembling  (that  of)  the  genus  Eurystomina 
excretory  duct,    canal  leading  from  renette  to  ampulla  near  excretory  pore 

excretory  pore,    opening  through  cuticle  (usually  cervical  or  cephalic),  at  which  the  renette  empties 
external  amphid,    the  cuticular  manifestation  of  the  amphid 
glottoid  apparatus,    valvular  structure  at  base  of  pharynx 

gubernaculum,    grooved  cuticularized  piece,  sometimes  paired,  through  which  the  spicula  slide 
head,     portion  of  nema  anterior  to  base  of  mouth  cavity 

jaws,    cuticular  framework  around  the  mouth,  for  grasping  and  holding;  fundamentally  3-parted 
labial  setae,    setae  of  the  '  'inner' '  circlet,  on  the  lips  or  close  to  the  mouth 

male  supplements,    male  organs,  usually  pre-  or  post-anal,  usually  a  single  ventral  row,  or  paired,  subventral 
mandibles,    hard,  strong,  biting  or  grasping  organs  around  the  mouth 
mandibular,    of  the  mandibles,  resembling  mandibles 

median  bulb,    swelling  of  the  oesophageal  wall  at  or  near  the  middle  of  its^length 
monospiral,    spiral  of  one  wind  or  not  much  more 
monospire,    spiral,  or  a  spiral,  of  one  wind  or  not  much  more 
mucron,    a  knob-like  ending,  shaped  like  that  on  the  end  of  a  lemon 
multispiral,    spiral  of  two  or  more  winds 
multispire,    spiral,  or  a  spiral,  of  two  or  more  winds 
neck,    portion  of  nema  anterior  to  base  of  oesophagus 
odontium  (odontia),    labial  tooth  (teeth) 

oesophagus,    portion  of  alimentary  tract  between  pharynx  and  intestine,  sometimes  surrounding  pharynx 
onchium  (onchia),    pharyngeal  tooth  (teeth) 

"palps,"     special  labial  appendages,  apparently  for  touching,  grasping,  or  getting  material  to  mouth 
percent,    percent  of  body  length,  or  distant  from  anterior  end  measured  in  percent  of  body  length 
pharyngeal  bulb,    muscular  swelling  of  the  oesophageal  wall  around  the  pharynx 
pharynx,    the  mouth  cavity  and  its  walls 
phasmids,    a  pair  of  cuticular  pores  on  the  tail 
plectoid,    resembling  (that  of)  the  genus  Plectus 
posterior  bulb,    cardiac  bulb,  q.v. 

probolae,    prominent  and  elaborate  specialized  appendages  encircling  the  mouth 
pseudonchs,    structures  in  pharynx  which  from  some  points  of  view  resemble  onchia 
renette,    a  cell  or  group  of  cells  emptying  through  the  excretory  duct(s) 
rhabditoid,    resembling  (that  of)  the  genus  Rhabditis 

sensory  papilla,    a  structure  in  the  amphidial  area  in  which  apparently  nerves  terminate 
setae,    hair-like  structures  on  the  cuticle 

sole,    the  region  of  attachment  of  the  special  ambulatory  setae  or  adhesion  tubes 
somatic  setae,    setae  general  on  the  surface  of  the  body  (opposed  to  cephalic,  caudal,  etc.  setae) 
spear,    a  long,  rather  slender  oncbium,  in  adult  usually  axial 

spicula,    male  intromittent  organs,  often  paired  each  an  elongate  cuticularized  framework,  extrusible  through  anus 
spinneret,    outlet,  usually  terminal,  of  the  caudal  glands,  enabling  nema  to  attach  itself 
striae,     fine  transverse  lines  in  the  cuticle 
striate(d),    showing  striae 
stylet,    a  long  slender  spear 

subcephalic  setae,    setae  on  the  head  but  behind  the  cephalic  circlet 
supplementary  organs,    see  male  supplements 

tooth,    element  of  buccal  armature, — onchium,  odontium,  spear  etc. 
tylenchoid,    resembling  (that  of)  the  genus  Tylenchus 

uvette,    rosette  or  group  of  cells  between  uterine  afferent  duct  and  efferent  duct  of  demanian  system 
vestibule,    entrance  to  the  mouth  cavity,  sometimes  a  distinct  chamber 
wings,    longitudinal  structures  in  cuticle,  or  projecting  from  it,  usually  lateral,  but  sometimes  numerous  and 

evenly  spaced  around  the  nema 


454  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 


PHARYNX  ABSENT,  or  so  obscure  as  easily  to  escape  notice  (for  alternative  see  page  458) 

Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both  (for  alternative  see  next  page) 
Amphid  not  known  or  obscure 
FoS5  1,  anterioTl^fph.  set.  0;  oesoph.  with  med.  bulb;  spinneret  0;  bursa  pr^jm^iL^otonchium  CobMgO 

Spinneret'none-  amphid  a  pore  at  lips;  cepn.  set.  2,  minute;  in  beetle  larvae (Neoapleetana  Steiner  1929) 

Spinneret  present;  oesoph.  without  median  bulb;  bursa  none;  marine 

Cephalic  setae  0;  cuticle  not  annulated;  spicula  long,  18%.  flexible.          Molgolaimus  Ditlev.  1921 

Cephalic  setae  numerous,  in  circlets  of  4;  cuticle  annulated,  exc.  on  head (Stilbonema  Cobb  1920) 

Hemispherical  cephalic  cap  suddenly  wider  than  neck,  edge  set  with  dots Mitrepharus  Linst.  1877 

Hemispherical  cephalic  cap  absent 

Spinneret  absent;  cephalic  setae  0;  wings  present;  in  soil;  J Litonema  Cobb  1920 

Spinneret  present  (Xuadella  ?);  ceph.  set.  present;  wings  0,  striae  uninterrupted;  marine 
Cuticle  not  annulated,  striae  none;  cephalic  setae  small 

Neck  8%;  cardiac  swelling  slight,  clavate Nuadella  Allgen  1927 

Neck  under  4%;  card,  bulb  broad;  cepb.  set.  in  3  circlets  of  4;  am  ph.  small,  near  bps..(Catanema  Cobb  1920) 
Cuticle  annulated,  exc.  on  head;  amphid  near  lips 

Setae  on  head,  labial  6,  ceph.  10;  contour  of  nema  ±  serrate;  pores  lateral (Leptonemella  Cobb  1920) 

Setae  on  head  in  circlets  of  4;  contour  of  nema  crenate;  pores  0;  nema  10  mm (Laxonema  Cobb  1920) 

Amphid  known 

External  amphid  not  spiral,  circular  nor  elliptical 

Head  a  hemispherical  cap,  suddenly  wider  than  neck,  edge  set  with  dots Mitrepharus  Linst.  1877 

Head  not  suddenly  wider  nor  cap-like 
Habitat  soil  about  roots 

Spinneret  present;  lips  6,  long,  revolute,  flower-like;  amph.  semicircular;  wings  2; '  9 '  Anthonema  Cobb  1906 
Spinneret  absent;  lips  not  long  nor  revolute;  cephalic  setae  0 

Wings  pres.  ;oesoph.  ±cephaloboid;striae±coarse;amph.  transverse.i  head-width; '  9  lotalaimus  Cobb  1920 
Wings  absent,  striae  not  interrupted 

Ceph.  papill.6,  conspic.;am ph. crescentic.head- width  back;  tail  3%,  rounded;  cf  only  Bolbinium  Cobb  1920 
Ceph.  papill.  tiny;  amph.  inconspic.,2  head-widths  back;tail  6-12%,  slender.conoid  Alaimus  de  Man  1880 
Habitat  marine;  cephalic  setae  and  spinneret  present 
Ambulatory  &  body  setae  absent;  nema  not  crooked 

Wings  pres.;  amph.  shepherd's  crook;  annules  under  300,  of  tile-like  elements; '  9  '  Ceramonema  Cobb  1920 

(cf.  Pselionema  Cobb  1933) 

Wings  0;  amph.  a  tran  verse  slit,  at  lips;  pores  lateral;  nema  ±2  mm.;  d1  only.  ..Leptonemella  Cobb  1920 
Ambulatory  &  body  setae  pres.;  amph.  crook-shape  to  spiral;  nema  ±S-shaped; '  9  ' 

Oesoph.  region  hardly  swollen;  card,  bulb  faint;  cerv.  striae  alike Notochaetosoma  Irwin-Smith  1918 

Oesoph.  region  swollen,  ovoid;  oesophageal  bulbs  1  or  2;  band  of  cervical 
striae  accentuated,  exc.  Tristicochaeta  falcatum 

Ventral  ambulatory  adhesion  tubes  or  setae  in  3  or  4  rows Tristicochaeta  Panceri  1878 

(  =  DraconemaCobb  1913) 

Ventral  ambulatory  adhesion  tubes  or  setae  in  2  rows Drepanonema  Cobb  1933 

(  =  Chaelosoma  Clap.  1863) 
External  amphid  spiral,  circular  or  elliptical 
Female  not  known;  J  only,  exc.  Bolbinium 

Annules ±90, prominent ;subdorsal setae 9  prs.;amph.  saccate;nema  10%+  wide Eudesmoscolex Steiner  1916 
Annules  0  or  not  prominent;  subdorsal  setae  0;  amphid  not  saccate;  nema  under  5%  wide 
Spinneret  absent;  cephalic  setae  0;  in  soil 

Cephalic  papillae  6,  conspicuous,  each  on  circular  base Bolbinium  Cobb  1920 

Cephalic  papillae  0  or  inconspicuous;  wings  double;  oesophagus  icephaloboid Litonema  Cobb  1920 

Spinneret  present 

Wings  single,  projecting;  amphid  almost  neck  width,  barely  longer  than  broad Antomicron  Cobb  1920 

Wings  0,  striae  not  interrupted  laterally 

Pharynx  with  basal  cuticularized  ring;  amphid  monospire (Cricolaimus  Southern  1914) 

Pharynx  without  basal  cuticularized  ring;  cephalic  setae  in  circlets  of  4 

Amphid  spiral,  of  2  winds (Alaimonema  Cobb  1920) 

Amphid  circular  or  elliptical 

Head  set  off  by  constriction,  spherical;  cephalic  setae  4;  amphid  on  neck Cinctonema  Cobb  1920 

Head  set  off  by  lack  of  annules,  if  at  all;  ceph.  set.  many;  amph.  small,  at  lips;  neck  2% 

Cuticle  without  annules;  head  not  set  off;  pharnyx  definite;  nema  3-4  mm (Catanema  Cobb  1920) 

Cuticle  with  annules  exc.  on  head;  pharnyx  obscure;  nema  10  mm Laxonema  Cobb  1920 

Female  known 
Ovary  1 ;  spinneret  none;  wings  0;  cephalic  setae  0  or  papilloid 

Oonad  9  posterior,  reflexed;  amphid  iobscure;  cardiac  swelling  slight;  in  soil (Alaimus  de  Man  1880) 

Gonad  9  anterior,  outstretched 

Habitat  marine;  anterior  oesophagus  fusiform,  cardiac  bulb  massive (Solenolaimus  Cobb  1894) 

Habitat  soil;  oesophagus  with  median  bulb;  bursa  present lotonchium  Cobb  1920 

Ovaries  2  ( = HemicVcli°Phora  de  Man  mi) 

Gonads  9  outstretched;  cephalic  setae  present;  marine  (for  alternative  see  next  page) 
bpmneret  doubtful  or  absent;  striae  very  fine  or  seen  with  difficulty 

Cephalic  setae  10,  subcephalic  4:  amphid  multispire (Laimelli  Cobb  1920) 

Cephalic  setae  4  or  8;  amphid  circular 

Pharynx  none;  cardiac  bulb  broad,  valvate;  tail  setaceous Terschellingia  de  Man  1888 

Pharynx  obconoid;  cardiac  bulb  pyriform,  sometimes  valvate (Cryptolaimus  Cobb  1933) 

opinneret  present 

Length  of  oval  monospiral  amphid  twice  its  width,  equalling  head  width Disconema  Fil.  1918 

Length  of  amphid  not  much  greater  than  its  width 

Gknd  ducts  cuticularized ,  pores  ventrad ,  cerv.  &  pre-anal ;  striae  coarse  Halaphanolaimus  Southern  1914 
Gland  ducts  and  pores  0;  striae  fine,  usually  plain 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  455 

Oesophagus  narrowed  from  middle  ;  cephalic  setae  4  ;  amphid  large  ;  head  narrowed  Cyartonema  Cobb  1920 
Oesophagus  not  narrowed;  cephalic  setae  present;  wings  0 
Setae  on  head  10,  4  short  specialized  at  tip;  cardiac  swelling  slight  ............  (Linhomoella  Cobb  1920) 

Setae  on  head  4-8,  less  than  1  head-width  long,  tip  not  specialized;  amphid  circular 
Pharynx  0;nema  small,  tapered  ;  card,  bulb  broad,  valvate;  tail  setaceous..  Terschellingia  de  Man  1888 
Pharynx  present  though  obscure 

Ceph.  set.  8-10;  card,  swelling  none  or  clavate,  non-valvate;  nema  not  tapered  Linhomoeus  Bast.  1865 
Ceph.  set.  4;cardiac  bulb  pyriform,  sometimes  valvate;  pharynx  obconoid  (Cryptolaimua  Cobb  1933) 
Gonads  9  reflexed;  amphid  circular,  oval  or  monospiral  (for  alternative  see  preceding  page) 
Spinneret  none;  amphid  a  pore  at  lips;  ceph.  set.  2,  minute;  in  beetle  larvae.  .  .  (Neoaplectana  Steiner  1929) 
Spinneret  present;  marine  exc.  Haliplectus 

Ambulatory  setae  0;  nema  not  crooked;  calvarium  absent,  or  not  truncate-conoid 

Med.  oes.  bulb  pres.;  ceph.  set.  0;  pores  in  submed.  rows;  water  &  brackish  soil..  (Haliplectus  Cobb  1913) 
Med.  oes.  bulb  absent;  marine 

Gland  ducts  cuticularized,  pores  cerv.  &  pre-anal;  striae  coarse.  ..  (Halaphanolaimus  Southern  1914) 
Gland  ducts  and  pores  none  or  not  cuticularized 
Head  expanded  opposite  monospiral  amphid;  cephalic  setae  4  ..................  Bolbonema  Cobb  1920 

Head  not  expanded 
Cephaljc  setae  0;  wings  0;  head  narrowed  from  amphid  forward  .......  Aegialoalaim.ua  de  Man  1907 

Cephalic  setae  present;  often  in  coastal  sand 

Amphid  oval,  1  head-width  long;  annules  fine;  wing  single;  ceph.  set.  4..Eutelolaimus  de  Man  1922 
Amphid  iequidiametral,  less  than  i  corresponding  neck  width 

Neck  21%;  striae  duplex;  wings  2;  ceph.  setae  4;  pharynx  narrow,  inconspicuous  Aplectus  Cobb  1914 
Neck  7%  or  less;  striae  not  duplex;  wings  0 

Cuticle  annulated;  amph.  small,  at  lips;  set.  on  head  many,  in  circles  of  4..(Stilbonema  Cobb  1920) 
Cuticle  finely  striated;  amphid  1  to  i  head-width,  often  monospiral 

Pharynx  straight.closed.with  pharyng.swelling;  nema  4-7  mm.;  width  0.3-0.8%  Laxus  Cobb  1894 
Pharynx  conoid,  often  with  small  onchium;  nema  2-4  mm.;  width  1.5-3.5%  Spirina  Fil.  1918 

Ambulatory  set.  forming  a  ventral  sole,  midbody  or  pre-anal:  nema  crooked;  calvarium  unstriated 
Nema  narrowest  in  cardiac  region,  ±S-shaped;  ambulatory  setae  hollow,  pre-anal;  annules  finer 
Oesoph.  region  hardly  swollen;  card,  bulb  faint;  cervical  striae  alike.  .  .  Notochaetosoma  Irwin-Smith  1918 
Oesoph.  region  swollen,  ovoid;  oesophageal  bulbs  1  or  2;  band  of  cervical 

striae  accentuated,  exc.  Tristicochaeta  falcatum 
Ventral  ambulatory  adhesion  tubes  or  setae  in  3  or  4  rows  .................  Tristicochaeta  Panceri  1878 

(  =  Draconema  Cobb  1913) 
Ventral  ambulatory  adhesion  tubes  or  setae  in  2  rows  ........................  Drepanonema  Cobb  1933 

(  =  Chaetosoma  Clap.  1863) 

Nema  narrowest  midway,  epsilon-shaped;  ambulatory  setae  not  open  at  end;  annules  coarser 
Sole  apparently  absent;  amphid  crescentic;  annules  98  ......................  Epsilonella  Steiner  1930 

Sole  present;  amphid  circular  or  monospiral 
Oesophagus  with  median  and  cardiac  bulbs  ..............................  Metepsilonema  Steiner  1927 

Oesophagus  with  cardiac  bulb  only 
Annules  80-112;  ambulatory  setae  slender,  falcate  .....................  Bathyepsilonema  Steiner  1927 

Annules  144-192;  ambulatory  setae  straight  or  slightly  arcuate 
Body  cylindroid,  if  crooked  faintly  so  ...............................  Archepsilonema  Steiner  1927 

Body  epsilon-like,  i.e.  body  arches  well  developed 
Cuticular  annules  homogeneous  in  structure  ..............  Prochaetosoma  Baylis  &  Daubney  1926 

(  =  Rhabdogaster  Metech.  1867) 
Cuticular  annules  not  homogeneous  in  structure 
"Axial"  part  of  the  cuticular  annules  hollow  ("frame  rings")  ...........  Epsilonema  Steiner  1927 

"Axial"  part  of  the  cuticular  annules  vacuolated,  etc  ..................  Epsilonoides  Steiner  1931 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling  (for  alternative  see  preceding  page) 
Amphid  not  known  or  obscure  (for  alternative  see  next  page) 
Female  not  known 

Habitat  freshwater  marshes  ;  setae  0;  spinneret  none;  neck  15-25%;  wings  double  Macroposthonia  de  Man  1880 
Habitat  marine 
Neck  8%,  cylindroid;  cephalic  setae  4(?);  tail  cylindroid  .............................  Nuadella  Allgen  1927 

Neck  16-43%,  itapering;  tail  conoid 
Spinneret  absent;  eyes  0;  neck  ±40%;  cephalic  setae  4  or  8  ...................  (Halalaimoides  Cobb  1933) 


Spinneret  present;  eyes  with  lenses;  neck  16-25% 
Cep 


phalic  setae  4  ;  head  set  off  by  cessation  of  very  fine  striation  ......................  Nemella  Cobb  1920 

Cephalic  setae  10;  striae  none;  amphid  and  setae  very  large;  adult  cf  only  .....  Enchelidium  Ehrenb.  1836 

(=Lasiomitus  Marion  1870 
=  Parasymplocostoma  Schulz  1932) 
Female  known 

Ovary  1,  anterior  exc.  Antopus  &  Thalassoalaimus  (for  alternative  see  next  page) 

Gonad  9  outstretched;  setae  4,  papilloid  ;  amphid  minute,  open  caudad;  marine  algae.  .  .(Litotes  Cobb  1920) 
Gonad  9  reflexed;  spinneret  none,  exc.  Antopus  &  Thalassoalaimus 
Cephalic  setae  6;  posterior  ovary  longer  than  anterior;  marine 
Pores  in  dorso-lateral  rows  ...........................................................  Antopus  Cobb  1933 

Pores  none  ................................................................  Thalassoalaimus  de  Man  1893 

Cephalic  setae  0;  vulva  near  anus;  spicula  2;  in  and  around  insects 
Spear  none  or  vestigial 
Uterus  not  evaginated 

Nema  serpentine;  oesophagus  and  intestine  persisting;  in  beetles  and  weevils.  .  .Bradynema  Strass.  1892 
Nema  saccate;  organs  degenerating  exc.  gonads  ...............................  Allantonema  Leuck.  1884 

(  =  TylenchomarphusFucbs  1914) 

Uterus  finally  evaginated;  oesophagus  and  intestine  degenerating  early 
Evaginated  uterus  many  times  as  large  as  nema  ..............................  Sphaerularia  Duf  .  1837 

Evaginated  uterus  not  much  larger  than  nema  ..................................  Asconema  Leuck.  1886 

(  =  Atractonema  Leuck.  1887) 

Spear  present,  at  least  in  larva  or  9  ;  organs  degenerating  in  adult 

Base  of  spear  ibulbed  ;  oes.  fusiform,  glands  abs.  in  a"  ;  bursa  pre-  and  post-anal  .  .  Scatonema  Bovien  1932 
Base  of  spear  straight;  spicula  nearly  straight 

Vulva  degenerating;  9  free  living;  bursa  pre-anal;  in  Passalus.  .Chondronema  Christie  &  Chitwood  1931 

(=Uracanthus  Dies.  1861) 


456  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Vulva  remaining  functional;  adult  9  parasitic;  gubernaculum  small 

Anus  none  or  vestigial;  in  cucumber  beetle,  Diabrotica Howardula  Cobb  1921 

Anus  persisting;  in  frit-fly,   Oscinella (Tylenchinema  Goodey  1930) 

Ovaries  2;  spinneret  present  exc.  Micoletzkyia  (for  alternative  see  preceding  page) 

Gonads   9   parallel,  posterior;  wings  10-12,  segmenting  the  annules Parocoma  Cobb  1920 

Gonads  9  opposed 
The  ovaries  outstretched;  marine 
Annules  few,  very  coarse;  amphid  saccate;  cephalic  setae  4;  nema  wide 

Number  of  annules  ±17,  secreted  annules  prominent,  separated;  head  small Desmoscolex  Clap.  1863 

Number  of  annules  32-91 ,  secreted  annules  absent ;  head  concave-quadrate  pyramidal. .  Tricoma  Cobb  1894 

(  =  Quadricoma  Fil.  1922) 

Annules  and  striae  0;  amphid  not  saccate;  cuticle  thick Phanodermella  Kreis  1928 

The  ovaries  reflexed 

Habitat  freshwater;  lips  3,  thick;  pharynx  narrow,  deep;  onchium  minute,  deepset  (Tripyla  Bast.  1865) 

(  =  Promononchus  Micol.  1923) 
Habitat  marine;  pharnyx  and  onchium  absent 

Annules  ±17,secreted  annules  prominent ;amphid  saccate;ceph.  set.  4;nema  wide  Desmoscolex  Clap.  1863 
Annules  not  few  nor  coarse;  amphid  not  saccate;  nema  ±slender 

Odontia  6;  lip  region  discoid;  ceph.  set.  4;  gland  ducts  oft  piercing  cuticle. . Stephanolaimus  Ditlev.  1918 
Odontia  0;  lip  region  not  set  off 

Head  set  off  by  constrict.;  ceph.  set.  8;  spicula  long,  slender;  gub.  complex  Micoletzkyia  Ditlev.  1926 
Head  not  set  off;  cephalic  setae  4  or  6 

Setae  on  head  4 ;  eyes  with  lenses ;  amphid  transverse-oval,  at  lips ;  among  algae (lonema  Cobb  1920) 

Setae  on  head  6 ;  eyes  none 

Spicula  short,  1  anal  body-diam.;  pores  0;  longest  cerv.  set.  J  neck-width.  .Paroxystomina  Micol.  1924 
Spicula  long,  several  anal  body-diameters 

Cervical  setae  in  6  longitudinal  rows;  pores  0;  ovaries  equally  long (Stenolaimus  Marion  1870) 

Cervical  setae  0;  pores  in  dorso-sublat.  rows;  ovary  post.,  anterior  a  rudiment. .  Antopus  Cobb  1933 


Amphid  known  (for  alternative  see  preceding  page) 
External  amphid  not  spiral,  circular  nor  elliptical  (for  alternative  i 


5  see  next  page) 
Female  not  known;  marine 
Neck  ±40%;amph.  narrow,  several  head- widths  long;tail  setaceous  ;spinneret  oft  0  Halalaimoides  Cobb  1933 
Neck  not  over  25%;  amphid  not  linear;  spinneret  present 
Wings  absent 

Odontia  6;lip  papill.  6;ceph.  set.  10(?) ;  subceph.  4,  jointed;  amph.  oval,  flat  caudad  Apodontium  Cobb  1920 
Odontia  0;  mouth  &  phar.  vestigial;  eyes,  amph.  &  set.  very  large;  adult  cf  only  Enchelidium  Ehrenb.  1836 

(  =  Lasiomitus  Marion  1870 
=  Parasymplocostoma  Schulz  1932) 
Wings  conspicuous 

Head  mitreform,  set  off  by  constriction;  striae  0;  cephalic  setae  small,  4  or  6 Xennella  Cobb  1920 

Head  not  mitreform,  set  off  by  lack  of  annulation;  annules  of  "tiles" ;  amph.  crook-shape 
Annules  over  700;  ceph.  set.  conspicuous,  8,  in  2  circlets;  onchia  0;  nema  3  mm.+  Pristionema  Cobb  1933 

Annules  under  300;  cephalic  setae  4;  onchium  present  (?);  nema  under  1  mm Pselionema  Cobb  1933 

(  =  Steineria  Fil.  1922) 
(cf.  Ceramonema  Cobb  1920) 
Female  known 
Ovary  1 

Gonad  ?  outstretched,  anterior ;ceph.  papill.  4;amph.  minute,  open  caudad ;marine  algae  Litotes  Cobb  1920 
Gonad  9  reflexed 

Spinneret  present;  ovary  posterior,  anterior  branch  short;  wings  0;  marine  Thalassoalaimus  de  Man  1893 
Spinneret  absent;  ovary  anterior;  in  soil  about  roots 
Wings  present,  striae  icoarse;  cephalic  papillae  4;  amphid  1  head-width  back.  ..lotalaimus  Cobb  1920 

Wings  0,  striae  0;  cephalic  papillae  minute;  amphid  2  head-widths  back Alaimus  de  Man  1880 

Ovaries  2 

Gonads  9  outstretched;  spinneret  present;  marine 

Annules  ±17,  secreted  annules  prominent  ;amphid  saccate  ;ceph.  setae  4  ;nema  wide  Desmoscolex  Clap.  1863 
Annules  not  few  nor  coarse;  amphid  not  saccate;  nema  ±slender 

Mouth  ventrad ;  amphid  huge,  bent,  dorsal  limb  the  longer Campylaimus  Cobb  1920 

Mouth  axial;  amphid  not  huge 

Amphid  narrow,  oft  many  head- widths  long;  eyes  0;  cephalic  setae  6,  subceph.  4  Halalaimusde'M.a.n  1888 
Amphid  "folded,"  not  over  1  head-width  long;  eyes  2,  sometimes  absent 

Oesophagus  and  lumen  widened  between  eyes  and  nerve  ring;  pharynx  obvious  (Coinonema  Cobb  1920) 
Oesophagus  and  lumen  not  widened;  pharynx  like  oesoph.  lining. . . .  Araeolaimoides  (de  Man)  Fil.  1918 
Gonads  9  reflexed 

Spinneret  0;  tail  3%;  ceph.  set.  10,  cervical  long,  1  group  at  amphid;  marine. . Platycomopsis  Ditlev.  1926 

(  =  DactylonemaFil.  1927) 
Spinneret  present 

Habitat  freshwater;  lips  3,  thick;  pharynx  narrow,  deep;  onchium  minute,  deepset  (Tripyla  Bast.  1865) 

(  =  Promononchus  Micol.  1923) 
Habitat  marine;  onchia  absent  ex<5.  Actinonema 

Amphid  narrow,  several  head- widths  long;  head  set  off,  with  colorless  cuticle 

Cephalic  &  subceph.  setae  ±1  head-width  apart;  cuticle  thin  (to  ,'j  radius) . . .  Halalaimus  de  Man  1888 
Cephalic  &  subceph.  setae  near  together  exc.  Nuada  isaitshikovi ;  cuticle  thick,  £  to  J  radius 

The  cuticle  i  to  1  radius  in  thickness Nuada  Southern  1914 

The  cuticle  i  to  i  radius  in  thickness Tycnodora  Cobb  1920 

Amphid  not  narrow  nor  very  long 

Shape  of  amphid  a  shepherd's  crook ;  each  annule  of  tile-like  elements Ceramonema  Cobb  1920 

(cf.  Pselionema  Cobb  1933) 

Shape  of  amphid  not  a  shepherd's  crook;  annules  not  of  tile-like  elements 

Annules  ±17,  secreted  annules  prominent  ;amph.  saccate;  ceph.set.4;  nema  wide  Desmoscolex  Clap.  1863 
Annules  not  few  nor  coarse;  amphid  not  saccate;  nema  ±slender 

Cutjcle  4  radius;  striae  coarse;  amphid  transverse,  J  head-width ;  setae  0 (Actinonema  Cobb  1920) 

Cuticle  not  thick;  amphid  not  a  transverse  slit;  eyes  with  lenses;  cephalic  setae  4 

Amphidial  gland  large,  conspicuous;  cephalic  setae  4,  j  head-width  long lonema  Cobb  1920 

Amphidial  gland  not  evident;  external  amph.  ±semicircular,  internal  elongate  Nemella  Cobb  1920 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  457 

External  amphid  spiral,  circular  or  elliptisal  (for  alternative  see  preceding  page) 
Female  not  known;  spinneret  present 

Habitat  brackish  earth;  wings  faint;  d"  supplements  on  neck,  ventral,  papilloid  Deontolaimus  de  Man  1880 
Habitat  marine 

Annules  ±90,  prominentjsubdorsal  setae 9  prs. ;amph.  saccate;  nema  10%  +  wide  Eudesmoscolex  Steiner  1916 
Annules  none  or  not  prominent;  subdorsal  setae  0;  amphid  not  sacsate;  nema  under  5%  wide 

Wing  small,  distinct;  amphid  almost  neck  width,  joined  dorsad (Antomicron  Cobb  1920) 

Wings  absent 
Mouth  and  digestive  system  vestigial;  setae  strongly  developed 

Eyes  absent Barbonema  Fil.  1927 

Eyes  and  amphid  strongly  developed ;  adult  cf  only (Enchelidium  Ehrenb.  1836) 

(  =  Lasiomitus  Marion  1870 
=Parasymplocostoma  Schulz  1932) 
Mouth  and  digestive  system  functional 

Odontia  6,  minute;  cephalic  setae  10(7),  subcephalic  4,  jointed Apodonlium  Cobb  1920 

Odontia  0;  cephalic  setae  0  or  rather  small 

Annules  rather  coarse;  setae  minute;  amphid  transverse-oval (Zygonemella  Cobb  1920) 

Annules  and  striae  none;  amphid  with  internal  pocket 

Cephaljc  setae  0;  amphid  long-oval,  internal  pocket  conspicuous Schislodera  Cobb  1920 

Cephalic  setae  small,  10;  cervical  setae  lateral;  amphid  small,  round  . . . .  (Leptosomalides  Fil.  1918) 
Female  known 

Ovary  1 ;  amphid  not  multispire 
Gonad  9  outstretched 
The  ovary  posterior;  spinneret  present 

Amphid  large,  open  caudad;  spinneret  sometimes  doubtful;  marine (Alaimella  Cobb  1920) 

Amphid  round;  anterior  ovary  rudimentary;  ceph.  set.  12,  in  2  circlets;  in  salt  marsh  Litinium  Cobb  1920 
The  ovary  anterior;  marine 

Pharynx  absent;  setae  4,  papilloid  ;amph.  small,  open  caudad;  spinneret  0;  among  algae  Litotes  Cobb  1920 
Pharynx  present,  often  minute;  setae  not  papilloid ;  amphid  larger,  circular;  spinneret  sometimes  0 

Onchia  0;  nema  small Monhystera  Bast.  1865 

(  =  Tacky hodites  Bast.  1865) 

Onchium  dorsal;  nema  often  several  millimetres  long Linhomoeus  Bast.  1865 

(  =  L.  obtusicaudatus  de  Man  1907) 
Gonad  9  reflexed 
Habitat  soil  or  fresh  water,  or  in  insects;  amphid  circular 

The  ovary  posterior;  spinneret  absent;  in  marshy  soil Alaimus  de  Man  1880 

The  ovary  anterior 

Spinneret   present ;   in  fresh   water Helalaimus  de  Cillis"  1917 

Spinneret  absent;  in  beetle,  Passalus Chondronema  Christie  &  Chitwood  1931 

(=Uracanthus  Dies.  1861) 

Habitat  marine;  ovary  posterior;  spinneret  present  (Alaimella  ?) 
Cephalic  setae  0 

Amphid  monospire;  in  sand  about  algae Nemanema  Cobb  1920 

Amphid  long-oval,  with  posterior  cuticularized  pocket Schistodera  Cobb  1920 

(cf.  Oxy stamina  Fil.  1921) 
Cephalic  setae  present 

Setae  on  head  4,  over  1  head-width  long;  striae  coarse;  amphid  large,  open  caudad. .  Alaimella  Cobb  1920 
Setae  10  or  16,  4  being  subcephalic;  striae  0  or  fine 

External  amphjd  circular;  cephalic  setae  12,  as  long  as  head  is  wide Lilinium  Cobb  1920 

External  amphid  oval,  pocket  cuticularized;  cephalic  setae  6  (4?) 

Amphidial  opening  small  transverse-oval,  or  circular Nemanemella  Fil.  1927 

Amphidial  opening  large,  long-oval Oxystomina  Fil.  1921 

(  =  Oxystoma  Butsch.  1874) 
Ovaries  2 

Gonads  9  outstretched;  marine 
Spinneret  absent 

Pharyngeal  bulb  definite;  ceph.  setae  6,  stout,  jointed;  amphid  circular;  in  sand  (Cytolaimium  Cobb  1920) 
Pharyngeal  bulb  absent 

Tail  3%,  eonoid;  ceph.  set.  10;  cervical  long,  bunched;  amphid  transverse-oval Platycoma  Cobb  1894 

Tail  over  12%,  conoid  then  cylindroid;  ceph.  set.  minute,  18,  in  3  circlets (Anticyathus  Cobb  1920) 

Spinneret  present 

Gland  ducts  cuticularized,  pores  cervical  &  pre-anal ;  striae  coarse (Halaphanolaimus  Southern  1914) 

Gland  ducts  and  pores  absent 

Annules  few,  very  coarse;  amphid  saccate;  cephalic  setae  4;  nema  wide 

Number  of  annules  ±17,  secreted  annules  prominent,  separated;  head  small. .  .Desmoscolex  Clap.  1863 
Number  of  annules  32-91 ,  secreted  annules  none;  head  concave-quadrate  pyramidal  Tricoma  Cobb  1894 

(  =  Quadricoma  Fil.  1922) 

Annules  if  present  not  coarse;  amphid  not  saccate 
Ampbid  multispire 

Cephalic  setae  10,  shorter  4  specialized  at  tips;  multispire  faint;  neck  5% Linhomoella  Cobb  1920 

Cephalic  setae  without  specialized  tips;  multispire  distinct;  neck  9-16% 

Male  ventral  pre-anal  supplementary  organs  papilloid Parasabatieria  de  Man  1907 

Male  ventral  pre-anal  supplementary  organs  absent Sabatieria  de  Rouville  1903 

Amphid  circular  (Southernia  slightly  irregular) 

Oesoph.  &  lumen  with  ellipsoid  enlargement  behind  eyes;  eyes  sometimes  0  Araeolaimus  de  Man  1888 
Oesoph.  without  median  enlargement;  eyes  0 
Cephalic  setae  4;  amphid  slightly  irregular Southernia  Allgen  1929 

Lips  distinct;  pharyngeal  bulb  pres.;  ceph.  set.  6,  stout,  jointed;  papillae  6.  .Cytolaimium  Cobb  1920 

Setae  on  head  10,  shorter  4  specialized  at  tips;  multispire  faint (Linhomoella  Cobb  1920) 

Setae  on  head  without  specialized  tips;  amphid  circular Linhomoeus  Bast.  1865 

Gonads  9  reflexed 
Spinneret  absent;  amphid  circular,  elliptical  or  monospiral;  wings  0  (for  alternative  see  next  page) 

Habitat  soil ;  internal  amphid  ±conspicuous (Basliama  de  Man  1876) 

Habitat  marine 
Tail  40%;  vulva  33%;  ceph.  set.  6,  subceph.  6;  internal  amphid  ±conspicuous. ...  Trefusia  de  Man  1893 


458  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Tail  under  10%;  vulva  ±60%;  ceph.  set.  ±1  head-width  long;  internal  amphid  not  conspicuous 
Ceph.  set  10,  cervical  long,  bunched,  in  &  2  flat  ones  at  amphid;  tail  3%,  conoid.  .Platycoma  Cobb  1894 
Ceph.  set.  4  (6?),  other  setae  0;  nema  cephalated  by  contraction;  tail  slender,  9%. . .  Acoma  Steiner  1916 
Spinneret  present  (for  alternative  see  preceding  page) 
Habitat  not  marine  (Aphanolaimus  ?);  contour  often  crenate 

Amphid  obscure,small;pharynx  narrow;onch.deepset;ceph.set. 6-10, oft  papilloid. .  .(Tripyla  Bast.  1865) 

(  = Promononchus  Micol.  1923) 
Amphid  distinct,  circular  or  spiral;  pharynx  none  or  closed;  ceph.  set.  6,  rarely  4  or  0 

Position  of  amphid  i-2  head-widths  back Aphanolaimus  de  Man  1880 

Position  of  amphid  3-4  head-widths  back Bastiania  de  Man  1876 

Habitat  marine 

Ambulatory  tubes  hollow;  body  setose,  annulated 

The  amphid  not  saccate;  ambulatory  tubes  ventral ;  setae  not  dense.  .Notochaetosoma  Irwin-Smith  1918 
The  amphid  saccate;  annules  coarse,  17-91;  nema  broad 

Body  setae  not  dense;  secondary  annules  secreted,  prominent (Desmoscolex  Clap.  1863) 

Body  setae  dense,  set  along  annules;  junction  oesoph.  &  intestine  indefinite. . . .  (Greeffiella  Cobb  1922) 

(  =  Trichoderma  Greeff  1869) 

Ambulatory  tubes  absent;  body  not  densely  setose;  not  annulated  exc.  Stephanolaimus 
Wings  ±50;nema  broad, ±16% ;neck  "collared" ;amphid  spiral ;pharynx  small..  .Richtersia  Steiner  1916 
Wings  if  present  not  numerous;  nema  slender,  under  5% 

Odontia  6;  ceph.  set.  4,  long;  lip  reg.  discoid;  gland  ducts  oft  projecting.  .Stephanolaimus  Ditlev.  1918 
Odontia  0;  cephalic  setae  not  longer  than  head  is  wide 

Gland  ducts  cuticularized,  pores  cervical  &  pre-anal;  striae  coarse . .  Halaphanolaimus  Southern  1914 
Gland  ducts  and  pores  none,  or  not  cuticularized 

The  amphid  multispire;  cephalic  setae  16,  ±1  head-width  long;  in  sand  .  .Nannolaimus  Cobb  1920 
The  amphid  not  multispire 

Amphid  at  lips,  transverse-oval,  with  large  gland;  eyes  with  lenses lonema  Cobb  1920 

Amphid  not  at  lips;  eyes  none  exc.  Leptosomatum 

Anterior  part  of  oesoph.  the  wider;  cervical  setae  0;  amphid  ±irregular. .  .Southernia  Allgen  1929 
Anterior  part  of  oesoph.  not  wider;  amphid  with  internal  pocket 
Oesophagus  crenate  posteriorly 

Calvarium  none;  labial  tubercles  none Stenolaimus  Marion  1870 

Calvarium  in  front  of  ceph.  set.,  margin  irregular;  labial  tubercles  3 Klugea  Fil.  1927 

(=Phanodermopsis  Ditlev.  1926,  in  part) 
Oesophagus  not  crenate  posteriorly 

Cephalic  setae  0;  pores  on  anterior  half  of  neck;  tail  rounded Leptosomatum  Bast.  1865 

Cephalic  setae  present;  pores  on  neck  absent 

Setae  on  neck  none;  cephaljc  setae  10,  ±1  head-width  long Leptosomella  Fil.  1927 

Setae  on  neck  in  lateral  series;  amphid  small 

Gubernaculum  present;  c?  pre-anal  ventral  supplement  tubular Anticoma  Bast.  1865 

Gubernaculum  none;  cf  pre-anal  ventral  supplement  papilloid. ..  (Anticomopsis  Micol.  1930) 

PHARYNX  PRESENT  (for  alternative  see  page  454) 

Wall  of  the  Pharynx  armed  (for  alternative  see  page  470) 
Armature  spear-like  or  apparently  so  (for  alternative  see  page  461) 

Spear  bulbed;  cephalic  setae  usually  0;  amph.  oft  obscure;  spinneret  0;  not  marine  exc.  Siphonolaimus  (pg.  460) 
Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling;  cephalic  setae  0 
Female  not  known  spear  with  retrorse  points  midway, base  3-lobed  ;bursalobed.  .Ecphyadophora  de  Man  1921 
Female  known;  ovary  1 
Gonad  9  reflexed 

Habit  free-living;  spear  (dorso-ventral  view)  arrow-headed;  ovary  posterior. . Pharetrolaimus  de  Man  1921 
Habit  parasitic  in  beetles,  etc.;  ovary  anterior 

Nema  saccate;  mouth  none,  organs  degenerated;  vulva  terminal (Allantonema  Leuck.  1884) 

(  =  Tylenchomorphus  Fuchs  1914) 
Nema  not  saccate;  anus  none  or  vestigial 

Spear  none;  parasitic  in  beetles,  weevils,  etc (Bradynema  Strass.  1892) 

Spear  present  in  young  9  only ;  in  cucumber  beetle,  Diabrotica Howardula  Cobb  1921 

Gonad  9  outstretched;  mostly  parasitic 

Anus  none  or  vestigial;  spear  ±vestigial;  in  cucumber  beetle,  Diabrotica (Howardula  Cobb  1921) 

Anus  present;  spear  present,  in  Aphelenchulus  reduced;  traces  median  bulb  sometimes  present 
Junction  oesoph.  &  intest.  definite;  anterior  oes.  fusiform,  isthmus  at  nerve  ring;  in  or  about  plants 

Habitat  crop  plants;  head  of  8  sectors;  terminus  of  tail  straight Neotylenchus  Steiner  1931 

Habitat  bladders  of  Fucus,  or  among  marine  algae;  head  of  6  sectors;  tail  hooked. .  Halenchus  Cobb  1933 
Junction  oesophagus  and  intestine  indefinite 
Spear  with  6  basal  lobes;  oesoph.  isthmus  at  nerve  ring;  in  decaying  vegetation. .  Hexatylus  Goodey  1926 

Spear  with  tripartite  base;  renette  ±body  length;  parasitic  in  insects Aphelenchulus  Cobb  1920 

Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both 
Female  not  known ;  spear  tripartite  at  base 

Cephalic  setae  4,  ±1  head-width  long;  oesoph.  swellings  med.  &  card.;  bursa  striate.  .Eutylenchus  Cobb  1913 
Cephalic  setae  0  or  papilloid 

Spear  with  retrorse  points  midway,  3-lobed  at  base;  bursa  small,  lobed Ecphyadophora  de  Man  1921 

Spear  without  retrorse  points  midway ;  oesophagus  without  median  bulb 

Pharyngeal  bulb  O.cardiac  i  neck  length ;ceph.set.0;nema  5%  wide;bursa  0. .  Tylencholaimellus  Cobb  1915 
Pharyngeal  bulb  pres.;ceph.set.6,papilloid;nema  9%  wide;tail  short  .rounded.  .Brachynemella  Cobb  1933 

(  =  Brachynema  Cobb  1893) 
Female  known 

Ovaries  2;  cephalic  setae  0;  spear  with  tripartite  base  (for  alternative  see  next  page) 
Gonads  9  outstretched  (for  alternative  see  next  page) 

Median  oesophageal  bulb  absent ;  spear  3-pronged  at  base ;  in  sandy  soil . . .  ( Tylolaimophorus  de  Man  1880) 
Median  oesophageal  bulb  present;  spear  3-lobed  at  base 

Junction  oesoph.&  intestine  indefinite ;annules  plain;tail  rounded.with  bursa. .  Hoplolaimus  Daday  1905 
Junction  oesoph.  &  intestine  definite,  exc.  sometimes  Tylenchus 
Spear-guide  wide  as  head,  forming  cuirasse  or  helmet;  bursa  none;  testes  2..Nemonchus  Cobb  1913 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  459 

Spear-guide  smaller,  slighter,  not  forming  cuirasse;  bursa  present 

Nema cephalated  by  constriction,  head  idiscoid;  spear  long;  bursa  loba.te....Dolichodorus  Cobb  1914 
Nema  cephalated  by  contraction  or  not  at  all ;  bursa  not  lobate 
Anterior  end  extensible.narrow  &  beak-like,inner  framework  cuticular. .  Tylenchorhynchus  Cobb  1913 

Anterior  end  never  narrowed  &  beak-like,  without  cuticular  framework Tylenchus  Bast.  1865 

Gonads  9  reflexed  (for  alternative  see  preceding  page) 
Structure  of  pharynx  obscure;  oesophagus  with  cardiac  swelling  only 

"Spear"  3  rods,  ant.  hinged  to  2  U-shaped  pieces,  post.  2  stalked  swellings. .  (Tylopharynx  de  Man  1876) 
"Spear"  rods  2-3,  base  heavy,  irreg.;  setae  0  or  papill.;  ovary  obscure. . .  Diphtherophora  de  Man  1880 

(  =  Chaolaimus  Cobb  1893 
=  Archionchus  Cobb  1913) 
Structure  of  pharynx  obvious 


Oesophagus  without  median  bulb,  cardiac  bulb  present 
Cardiac  swelling  cylindroid  (i.e.  oesophagus  dorylaimoid) 
Oral  spear  large,  over  5%,  base  3-bulbed  but  not  trif urcate 


.       •  large,  over  5%,  base  3-bulbed  but  not  trif  urcate Xiphinema  Cobb  1913 

Oral  spear  smaller,  under  5%,  base  trif  urcate (Tylencholaimus  de  Man  1876) 

Cardiac  swelling  pyriform  to  clavate 

Spear  3-bulbed  at  base,  ±stout;  amphid  protrusile,  tube  cuticularized Triplonchium  Cobb  1920 

Spear  3-pronged;  amph.  J  head-width,  transverse-oval;  labial  papillae  6  Tylolaimophorus  de  Man  1880 
Oesophagus  with  median  bulb,  often  with  cardiac  swelling  also 

Body  ±thick,  not  serpentine;  9  and  larval  forms Heterodera  Schmidt  1871 

(  =  Meloidogyne  Goldi  1887 
=  Caconema  Cobb  1924) 
Body  ±serpentine 

Junction  oesoph.&  intestine  indef .  ;annules  plain;tail  rounded, with  bursa. .  (Hoplolaimus  Daday  1905) 
Junction  oesoph.  &  intestine  definite;  bursa  none;  tf  and  larval  forms 
Spear  really  the  apophyses  of  3  movable  onchia  at  base  anterior  pharynx —  Tylenchodon  Fuchs  1930 

Spear  tylenchoid Heterodera  Schmidt  1871 

(  =  Mdoidogyne  Goldi  1887 
=  Caconema  Cobb  1924) 
Ovary  1  (for  alternative  see  preceding  page) 
Gonad  9  reflexed;  setae  0 

Spear  trif  urcate  half  its  length,  base  swollen;  oesoph.  with  cardiac  bulb  only.  .Dory  Ilium  Cobb  1920 
Spear  furcate  at  base  only;  bulbs  usually  3 
Body  thick,  inert;  parasitic  9  forms 

Nema  body  swollen,  head  and  neck  narrow;  vulva  90%;  in  citrus  roots Tylenchulus  Cobb  1913 

Nema  sausage-shaped ;organs  degenerated exc.gonads;  vulva  term.;  in  insects  Allantonema  Leuck.  1884 

(  =  Tylenchomarphus  Fuchs  1914) 
Body  islender  or  serpentine 
Oral  spear  ±  vestigial;  median  bulb  ireduced;  cf  and  larval  forms 

Habitat  in  citrus  roots  and  soil Tylenchulus  Cobb  1913 

Habitat  in  and  around  wood-boring  beetles Allantonema  Leuck.  1884 

(=Tylenchomorphus  Fuchs  1914) 
Oral  spear  well  developed 
Median  oesophageal  bulb  elongate;  vulva  over  70%,  ovary  anterior;  bursa  none 

Spear  3-4%;  annules  0;  median  bulb  ireduced;  anus  not  functional Tylenchulus  Cobb  1913 

Spear  8-23%;annules  under  150,retrorse;median  bulb  oft  valvate;vulva  70-95%.  .Ogma  Southern  1914 

(=Iota  Cobb  1913) 
Median  oesophageal  bulb  absent 

"Spear"  rods  2-3,  base  heavy,  irreg.;  setae  0  or  papilloid;  vulva  5Q%... Diphtherophora  de  Man  1880 

(  =  Chaolaimus  Cobb  1893 
=  Archionchus  Cobb  1913) 

"Spear"  of  usual  structure,  shaft  distinct,  base  tripartite 

Tip  of  spear  tapering,  posterior  prongs  little  swollen;  vulva  33-72%.  .  Tylencholaimus  de  Man  1876 
Tip  of  spear  (dorso-ventral  view)  arrow-headed;  vulva  25%,  ovary  post.  Pharetrolaimus  de  Man  1921 
Gonad  9  outstretched 

Habitat  marine;"spear"  an  evertible  pharyng. lining ;amph. round ;neck  4%  Siphonolaimus  de  Man  1893 
Habitat  not  marine;  median  oesophageal  bulb  present  (Neotylenchus  ?) 

Cephalic  setae  4,  li  head-widths  long;  longitudinal  striae  10;  in  cranberry  bog.  .Atylenchus  Cobb  1913 
Cephalic  setae  0 

Dorsal  oes.gland  emptying  at  med.bulb;junct.oes.&intest. indef.  ;bursa  0  A phelenchoides  Fischer  1894 

(  =  Seinura  Fuchs  1931 

=Parasitaphelenchus  Fuchs  1930 

=  Pathoaphelenchus  (Cobb)  Steiner  1931) 

Dorsal  oes.  gland  emptying  at  base  of  spear;  genera  tylenchoid 

Spear  under  5%;  junction  oesoph.  &  intest.  usually  definite;  nema  under  5%  wide;  bursa  present 
Anterior  oesoph.  with  median  bulb;  head  of  6  sectors;  tail  without  mucron.  ...Tylenchus  Bast.  1865 
Anterior  oesoph.  fusiform  to  isthmus;  median  bulb  not  definite;  in  or  about  plants 

Habitat  crop  plants;  head  of  8  sectors;  terminus  of  tail  straight Neotylenchus  Steiner  1931 

Habitat  bladders  of  Fucus,  &am'g  marine  algae;head  of  6  sectors ;  tail  hooked  Halenchus  Cobb  1933 
Spear  8-24%;  oesoph.  lining  flexible,  looping;  nema  5%+  wide;  bursa  0;  vulva  72-94% 
Base  of  spear  bulbed,  not  fluked;  annules  over  100,  not  retrorse;  junct.  oes.  &  intest.  definite 

Oral  area  not  raised;  annulation  fine Paratylenchus  Micol.  1922 

Oral  area  raised,  surrounded  by  "fossa" ;  annulation  rather  coarse Procriconema  Micol.  1925 

Base  of  spear  anchor-shaped  (fluked);  annules  under  150,  retrorse;  junct.  oes.  &  intest.  indef. 

Scales,  prickles  and  fringes  absent  from  annules Criconema  Hoff manner  &  Menzel  1914 

Scales,  prickles  or  fringes  ornamenting  the  annules Ogma  Southern  1914 

(=Iota  Cobb  1913) 


460  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Spear  plain,  i.e.  not  bulbed  at  base  (for  alternative  see  page  458) 
Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling 
Amphid  known 

External  amph.reniform;  dorsal  pnch.  small,  at  spear  base;  ovary  ant.;  not  marine  Enoplocheilus  Kreis  1932 
External  amphid  circular,  elliptical  or  monospiral 
Spinneret  absent;  anus  reduced;  parasitic  in  beetles 
Pharyng.bulb strong.head swollen;  spear  1.5%;  junct.oesoph.&  intest.  indef. ;~9  (Rhabdonchus  Cobb  1933) 

Pharyng.  bulb  none;  spear  vestigial;  in  beetle,  Passalus;  '9 Chondronema  Christie  &  Chitwood  1931 

(=  Uracanthus  Dies.  1861) 
Spinneret  present;  marine 

Annules  coarse  exc.  on  head ;  onch.  spear-like,  axial ;  body  set.  in  long,  rows ;  ~  9  ~  Aculeonchus  Kreis  1928 
Annules  none  or  fine;  head  not  expanded;  cephalic  setae  4 

Striae  of  dots,  larger  laterally;  amph.  multispire;  spicula  2-jointed;  ~9~.  .Dorylaimopsis  Ditlev.  1918 

(  =  Xinema  Cobb  1920) 
Striae  0;  amph.  monospire;  spicula  entire;  junct.oes.  &  intest.  obscured  by  glands;  eyes  present 

Spear  0.3%,  a  thickening  of  dorsal  phsryngeal  wall;  ovaries  1  or  2,  reflexed (Onchium  Cobb  1920) 

Spear  more  obvious,  1.5%;  '  S ' Onchulella  Cobb  1920 

Amphid  unknown  or  obscure 

Female  not  known;  spear  a  small  prod  at  lips;  marine Rhinonema  Allgen  1927 

Female  known 

Spinneret  present;  ovaries  2;  marine 
Calvariumsubcuticular;  spear  long,  slender;  set.  on  head  long;  nema  6  mm.  Thoracostomopsis  Ditlev.  1918 

Calvarium  none;  head  not  suddenly  narrowed;  spear  short;  ovaries  reflexed (Onchulella  Cobb  1920) 

Spinneret  absent;  ovary  1;  not  marine 

The  female  saccate,  sausage-shaped;  vulva  terminal,  ovary  reflexed;  in  beetles  Allantonema  Leuck.  1884 

(=Tylenchomarphus  Fuchs  1914) 

The  female  ielongate,  usually  not  slender;  vulva  posterior,  ovary  anterior 

Ovary  outstretched;  anus  present;  spear  a  mere  prod,  reduced  in  a";  wings  O...Iotonchium  Cobb  1920 
Ovary  reflexed  exc.  Rhabdonchus;  anus  none  or  reduced;  parasitic  in  insects 

Spear  long,  slender,  in  muscular  bulb,  head  swollen;  junct.  oes.  &  intest.  indef.  .Rhabdonchus  Cobb  1933 
Spear  vestigial,  minute  or  none;  pharyngeal  bulb  absent 

Mouth  and  spear  absent;  in  beetles,  weevils,  etc (Bradynema  Strass.  1892) 

Mouth  and  spear  present  in  young  9  only;  in  beetles,  frit  fly,  etc. 

'     Vulva  degenerating;  9  free-living ;bursa  pre-anal;in  Passalus  Chondronema  Christie  &  Chitwood  1931 

(=  Uracanthus  Dies.  1861) 
Vulva  remaining  functional;  adult  9  parasitic;  gubernaculum  small 

Anus  none  or  vestigial;  in  cucumber  beetle,  Diabrotica Howardula  Cobb  1921 

Anus  persisting;  in  frit-fly,  Oscinella (Tylenchinema  Goodey  1930) 


Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both 
Amphid  nc 


r   ._  not  known  or  obscure 

Spinneret  present;  cardiac  swelling  slight;  spear  a  small  prod  at  lips;  J (Rhinonema  Allgen  1927) 

Spinneret  absent;  cephalic  setae  0 

Nema  parasitic,  saccate  female;  vulva  terminal;  in  beetles,  etc.;  '9 (Allantonema  Leuck.  1884) 

(=Tylenchomorphits  Fuchs  1914) 
Nema  free-living 

Armature  a  minute  labial  prod;  expanding  headsuddenly  truncate;  vulva88%;~  9  lotonchium  Cobb  1920 
Armature  an  obvious  spear 

Spear  closed,  bent  dorsad  at  tip  when  extruded;  '9 (Campydora  Cobb  1920) 

Spear  open,  a  hollow  passage;  not  bent  at  tip 

Lips  petaloid,  lip  reg.  expanded,  discoid ;  oesoph.  dorylaimoid ;  spear  small ;  '  9  '  Antholaimus  Cobb  1913 
Lips  0;  median  bulb  valvate,  with  outlets  of  3  glands;  junction  oesoph.  &  intestine  indefinite;  ~9 

Gubernaculum  and  bursa  present Aphelenchus  Bast.  1865 

(=*Isonchus  Cobb  1913) 

Gubernaculum  and  bursa  absent Aphelenchoides  Fischer  1894 

(  =  Seinura  Fuchs  1931 
*=Parasilaphelenchus  Fuchs  1930 
=Pathoaphelenchus  (Cobb)  Steiner  1931) 
Ampbid  known 

External  amphid  spiral,  circular  or  elliptical  (for  alternative  see  next  page) 
Spinneret  present;  amphid  labial,  ±  spiral;  "spear"  filling  posterior  pharynx;  marine 

Width  of  nema  3.5%;  pharyngeal  bulb  definite;  '  9 ' Onyx  Cobb  1891 

Width  of  nema  7%;  pharyngeal  bulb  faint;  J Oistolaimus  Ditlev.  1921 

(cf.  Onyx  Cobb  1891) 

Spinneret  absent;  amphid  circular  or  elliptical 

Anus  none;setae  0;  pharyng.bulb  strong;  junct.oes.&intest.  indef.;  in  beetles; ~ 9 Rhabdonchiu  Cobb  1933 
Anus  present;  nema  free-living 

Cephalic  setae  10,  Siphonolaimus  sometimes  0;  amphid  circular 
Habitat  marine ;"spear"  evertiblephar.lining;nema5-10mm.;neck4%;  ~  9  Siphonolaimus  de  Man  1893 

Habitat  moist  soil;  spear  tooth-like;  nema  0.85  mm.;  neck  16% Odontolaimus  de  Man  1880 

(=Neonchus  Cobb  1893) 
Cephalic  setae  0 

Spear  bent  dorsad  at  tip  when  extruded;  amphid  small,  oval,  at  lips;  '9 Campydora  Cobb  1920 

Spear  not  bent  at  tip 

Med.oes.bulb  0;nema  ±dorylaimoid;lab.papillae  6,cepb.6;ovaries  2  (Tylolaimophorus  de  Man  1880) 
Med.  oes.  bulb  valvate;  nema  ±tylenchoid;  papillae  0;  amphid  oval,  near  lips 
Junction  of  oesophagus  and  intestine  ±definite 

Gubernaculum  and  bursa  absent;  tail  often  with  mucron;  ~9 Paraphelenchus  Micol.  1925 

Gubernaculum  small;  bursa  without  ribs;  tail  slender,  long-conoid;  ~9~  Psilenchus  de  Man  1921 
Junction  oesoph.  &  intestine  indefinite;  oes.  gland  outlets  at  med.  bulb;  tail  short;  ~9 

Bursa  and  gubernaculum  present Aphelenchus  Bast.  1865 

(=Isonchus  Cobb  1913) 

Bursa  and  gubernaculum  absent Aphelenchoides  Fischer  1894 

(  =  Seinura  Fuchs  1931 

=Parasitaphelenchus  Fuchs  1930 

=Pathoaphelenchus  (Cobb)  Steiner  1931) 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  461 

External  amphid  a  transverse  slit,  oft  at  lip  reg.;  ceph.  set.  0;  fresh  water  or  soil  (from  preceding  page) 
Ovary  1,  reflexed;  spinneret  0  (Oionchus  ?) 
Spear  a  closed  cutting  or  pricking  organ,  ±tooth-like;  vulva  55-60%,  ovary  anterior 

Spinneret  (?)  present;  spear  straight Oionchus  Cobb  1913 

Spinneret  absent;  tip  of  spear  bent  dorsad  when  extruded;  amphid  elliptical  ...Campydora  Cobb  1920 
bpear  open  at  end,  a  hollow  passage,  tip  not  bent;  oesophagus  dorylaimoid 

Anterior  f  of  oesophagus  narrow;  cardiac  swelling  set  off  by  constriction (Doryllium  Cobb  1920) 

Anterior  |-j  of  oesophagus  narrow;  both  parts  cylindroid 

Narrow  part  of  oesophagus  set  off  behind  by  constriction Axonchium  Cobb  1920 

Narrow  part  of  oesophagus  iconfluent  with  wider  posterior  part;  9 ' (Dorylaimus  Duj.  1845) 

Ovaries  2,  reflexed;  9esophagus  idorylaimoid 
Spear  a  closed  cutting  or  pricking  organ,  ±tooth-like 
The  spear  long,  slender,  flexible;  cardiac  swelling  slight,  basal,  iclavate 

Guide  rings  for  spear  absent;  spear  30-40%  of  neck  length Trichodorus  Cobb  1913 

Guide  rings  for  spear  present;  spear  ±20%  of  neck  length Leptonchus  Cobb  1920 

Ihe  spear  shorter,  less  slender,  less  flexible;  cardiac  swelling  cylindroid,  i-|  oesophagus 

Tip  of  ventral  spear  oblique,  ventrad  when  extruded;  nema  6-10  mm Sectonema  Thome  1930 

Tip  of  submedian  spear  straight;  nema  under  4.5  mm Nygolaimus  Cobb  1913 

Spear  open  at  end,  a  hollow  passage 
Pharynx  with  cup-shaped  anterior  portion 

Cup-shaped  portion  with  6  ribs;  spear  with  guiding  ring Actinolaimus  Cobb  1913 

Cup-shaped  portion  without  ribs ;  spear  without  guide  ring ;  lip  region  discoid . .  Antholaimus  Cobb  1913 
Pharynx  without  cup-shaped  anterior  portion 

Oesophagus  with  fusiform  "bulb"  behind  spear Dorylaimellus  Cobb  1913 

Oesophagus  without  swelling  behind  spear 

Lip  region  discoid,  much  expanded Discolaimus  Cobb  1913 

Lip  region  usually  not  discoid,  expanded  little  or  not  at  all 

Labial  papillae  0,  cephalic  6;  circumoral  ridge  present;  vulva  34% Chrysonema  Thome  1929 

Labial  papillae  6,  cephalic  6;  circumoral  ridge  absent Dorylaimus  Duj.  1845 

Armature  of  one  or  more  teeth  (odontia  or  onchia)  (for  alternative  see  page  458) 
Tooth  (onchium)  1  (for  alternative  see  page  465) 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling;  amphid  occasionally  obscure  (pg.  463) 
External  amphid  not  spiral,  circular  nor  elliptical  (for  alternative  see  next  page) 
Female  not  known 

Habitat  soil;spinneret  0;phar.i  neck-length ;onch.outward-acting;oes.dorylaimoid.  .Nanonema  Cobb  1905 

(=Cephalonema  Cobb  1893) 
Habitat  marine 

Annules  coarse,  elements  tile-like ;  amphid  crook-shape ;  ceph.  set.  4 ;  nema  0.7  mm .  Pselionema  Cobb  1933 

(=Steineria  Fil.  1922) 
Annules  not  coarse;  amphid  not  crook-shape 

Onchium  small,  a  labial  prod;  cephalic  setae  6 Rhinonema  Allgen  1927 

Onchium  pharyngeal 

Labial  set.  6,  cephalic  10;  onchium  dorsal;  nema  0.5%  wide;  amphid  transverse  Trileptium  Cobb  1933 

(  =  Trilepta  Cobb  1920) 

Labial  set.  0,  cephalic  6;  onchium  ventral;  nema  over  4%  wide Doryonchvs  Kreis  1932 

(cf.  Symplocostoma  Bast.  1865) 
Female  known 
Ovary  1 ;  habitat  not  marine 

Median  onchium  spear-like,  dorsal  onchium  minute,  basal Enoplocheilus  Kreis  1932 

Median  spear-like  onchium  absent;  ovary  reflexed;  Enoplidae 

Pharynx  tubular,  depth  10  times  width ;  tooth  basal ;  cephalic  setae  0 Cryptonchus  Cobb  1913 

(  =  Ditlevsenia  Micol.  1925) 
Pharynx  conoid  when  open,  depth  not  over  3  times  width 

Tooth  minute,  basal,  deep-set;  denticles  0;  spinneret  terminal Trischistoma  Cobb  1913 

Tooth  large,  subventral;  denticles  present;  other  onchia  2;  spinneret  ventr&d(Mononchulus  Cobb  1918) 
Ovaries  2 

Gonads  9  outstretched;  spinneret  present;  striae  plain;  marine Mononcholaimus  Kreis  1924 

Gonads  9  reflexed 

Spinneret  absent;  amphidial  opening  oval  or  a  transverse  slit 
Base  of  tooth  without  "flukes";  cephalic  setae  6;  onchium  large,  acute;  in  soil.  .Onchulus  Cobb  1920 

Base  of  tooth  anchor-shaped,  "flukes"  dorsad  and  ventrad Diphtherophora  de  Man  1880 

(  =  Chaolaimus  Cobb  1893 
=Archionchus  Cobb  1913) 

Spinneret  present,  exc.  sometimes  Eurystominae 
Habitat  not  marine;  Trilobinae 

Pharynx  closed;  lips  3 ;  onchium  minute,  basal,  deepset Tripyla  Bast.  1865 

(=Promononchus  Micol.  1923) 

Pharynx  open,  domed,  larger;  lips  6;  onchia  often  more  than  1 Trilobus  Bast.  1865 

Habitat  marine 

Striae  conspicuous,  resolvable  into  dots  or  rod-like  elements;  Chromadoridae 

Amphid  at  lips,  lenticular,  oft  obscure;  cuticle  of  "basket-work"  on  neck  Euchromadora  de  Man  1886 

(=Graphonema  Cobb  1898) 
Amphid  not  at  lips,  of  ±even  width,  conspicuous,  reaching  nearly  across  head 

Cephalic  setae  0;  annules  of  obscure  rod-like  elements;  spicula  entire Actinonema  Cobb  1920 

Cephalic  setae  10;  annules  on  neck  of  "basket-work" 

Spicula  entire;  amphid  a  wide  transverse  oval Pareuchromadora  Stekhoven  &  Adams  193 

Spicula  of  2  sections ;  amphid  a  narrow  slit  of  even  width R hips  Cobb  1920 

Striae  0,  or  plain  and  very  fane 

External  amph. bent  or  crook-shaped, plate  oval,  1  head-width  ;"tooth"  minute  Diplopeltis  Cobb  1905 

(  =  Dipeltis  Cobb  1891 
=Discophora  Villot  1875) 
External  amphid  not  crook-shaped,  plate  absent;  Enoplidae 

Head  with  elaborate,  ornate  calvarium Deontostoma  Fil.  1916 

Head  without  calvarium 
Pharynx  of  single  chamber;  cephalic  setae  10 


462  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Mouth  cavity  iquadrate;  onchium  minute,  close  against  wall;  eyes  0  Anoncholaimus  Cobb  1920 
Mouth  cavity  twice  as  deep  as  wide;  dorsal  qnch.  bent  in  over  pharynx  Asymmetrella  Cobb  1920 
Pharynx  of  more  than  1  chamber;  large  onchium  sub  ventral 
Onchium  conoid  to  base  of  short  stylet;  phar.  ±quadrate;  cf  supplements  eurystomoid 

Bulbs  of  oesophagus  5-8,  serial,  contiguous Bolbella  Cobb  1920 

Bulbs  of  oesophagus  none 

Cervical  setae  long,  about  30;  cf  supplements  weakly  developed Ledomtia  Fil.  1927 

Cervical  setae  0  or  minute;  cf  supplements  well  developed Ewystomina  Fil.  1921 

(=Eurystoma  Marion  1870 
=Marionella  Cobb  1922) 
Onchium  a  long  stylet;  phar.  much  deeper  than  broad;  cf  an  enchelid 

Anterior  oesophagus  (pharynx  ?)  narrower,  lumen  wide Calyptronema  Marion  1870 

(  =  Catalaimus  Cobb  1920) 
Anterior  oesophagus  not  differentiated 

Vestibule  set  off  by  row  of  "comma"  markings;  pharyng.  rings  3  Symplocostomella  Micol.  1930 
Vestibule  not  set  off  by  a  ring  or  rows  of  denticles  or  markings. . Symplocostoma  Bast.  1865 
External  amphid  spiral,  circular  or  elliptical  (for  alternative  see  preceding  page) 
Female  not  known;  marine 

Amphid multispire,big;phar.ribbed,complex;onch.3;cf  supplements chromadoroid  Pomponemo  Cobb  1917 
Amphid  circular  or  oval  (Rhinonema,  Doryonchus?) 

Annules  of  dots  &  rods.altered  laterally  ;amph. trans  verse-oval  Pareuchromadora  Stekhoven  &  Adams  1931 
Annules  none  or  not  ornamented;  cephalic  cuticle  not  thickened 
Cephalic  setae  6 

Onchium  a  minute  labial  prod Rhinonema  Allgen  1927 

Onchium  ventral,  pharyngeal,  slender,  lance-like Doryonchus  Kreis  1932 

(cf.  Symplocostoma  Bast.  1865) 
Cephalic  setae  8  or  10 

Oesophagus  surrounding  phar.;  onch.  opposed  by  denticles;  amph.  long-oval  Anaxonchium  Cobb  1920 
Oesophagus  ceasing  at  base  of  pharynx;  denticles  0;  amphid  smaller,  circular;  Enoplidae 

Pharynx  of  1  chamber;  onchium  digitate Cophonchus  Cobb  1920 

Pharynx  of  2  chambers;  onchium  a  slender,  subventral  stylet Isonemella  Cobb  1920 

Female  known 
Ovary  1,  anterior;  onchium  dorsal 

Striae  of  dots;  pharynx  cyatholaimoid;  '9 Dentatonema  Kreis  1928 

Striae  none  or  plain;  pharynx  not  cyatholaimoid 

Pharynx  large,  open;  onchium  large,  apex  far  forward;  amphid  with  pocket  Pseudodilaimus  Kreis  1928 
Pharynx  small  or  closed,  onchium  basal  or  deepset,  small 

Gonad  9  reflexed;  striae  0;  spinneret  small;  vulva  80%;  in  soil Trischistoma  Cobb  1913 

Gonad  9  outstretched;  onchium  dorsal;  amphid  circular 

The  pharynx  very  small;  oesophagus  strongly  developed Prosphaerplaimits  Fil.  1918 

The  pharynx  }  head-width,  as  deep  as  wide;  onch.  central;  in  warm  salt  springs. .  .Anticyclus  Cobb  1920 
Ovaries  2 
Gonads  9  outstretched;  spinneret  present;  marine 

Amphid  not  known;  striae  plain Mononcholaimus  Kreis  1924 

Amphid  multispire;  striae  of  dots 

Head  setose;  striae  not  altered  laterally;  spiculalong;  apophysis  absent Comesoma  Bast.  1865 

Head  less  setose;  spicula  short;  gubernaculum  with  apophysis 

Male  ventral  pre-anal  supplementary  organs  small,  papilloid Parasabatieria  de  Man  1907 

Male  supplementary  organs  absent Sabatieria  de  Rouville  1903 

Gonads  9  reflexed 

Habitat  soil  or  fresh  water;  cuticle  without  pores;  wings  0 

Amphid  multispire;  pharynx  conoid;  spinneret  present;  cf  supplements  none  Nannonchus  Cobb  1913 
Amphid  elliptical,  with  internal  pocket;  pharynx  not  conoid 

Cephalic  setae  0;  labial  papillae  in  2  circlets;  spinneret  usually  present Mononchus  Bast.  1865 

Cephalic  set.  6,  jointed;  labial  papillae  1  circlet;  spinneret  0;  about  roots Cyathonchus  Cobb  1933 

Habitat  marine  and  brackish  waters 

Nema  broad,  16%;  wings  ±50;  neck  region  "collared" ;  pharynx  narrow (Richtersia  Steiner  1916) 

Nema  slender,  not  over  5%;  wings  0  exc.  Rhinema  12 

Amphid  multispire;  striae  of  dots;  cuticular  pores  pres.;  vestibule  with  12  (6  double  ?)  ribs 
Large  cf  supplement  tub  ular.anteriorto  smallsupplements;nema  viviparous  Acanthonchus  Cobb  1920 

(  =  Seuratia  Ditlev.  1918 
=  Seuratiella  Ditlev.  1922) 

Large  cf  supplement  absent,  others  if  tubular  small;  nema  usually  oviparous 
Phar.  tubular  behind  onch.;  gubernacula  not  serrate;  cf  papill.  setose  Paracyatholaimus  Micol.  1922 
Phar.  cyathiform;  gubernacula  serrate  distally;  cf  setose  papillae  none 

Dorsal  onchium  large,  acute,  projecting;  striae  altered  laterally Paracanthonchus  Micol.  1924 

Dorsal  onchium  0  or  not  projecting;  pharyngeal  ribs  extending  to  base 

Tail  setaceous;  onchium  small;  cf  papillae  present  or  not Longicyalholaimus  Micol.  1924 

Tail  not  setaceous 

Dots  larger  laterally;  cf  supplements  tubular;  gubernac.  oft  joined  Praeacanthonchus  Micol.  1924 
Dots  not  larger  laterally;  cf  tubular  supplements  0;  gubernacula  joined  Cyatholaimus  Bast.  1865 

(  =  Necticonema  Marion  1870) 
Amphid  circular,  elliptical  or  monospiral 

Wings  12,  markings  V-shaped;  pharyng.  bulb  stronger  dorsad ;  amphid  circular Rhinema  Cobb  1920 

Wings  0;  striae  plain 


„       striae  pi 

Dorsal  pharyng.  wall  thick,  tooth-like;  amph.  monospire  at  lips;  ceph.  set.  4;  renette  far  back 
Oesoph. glands  obscuring  junct.intest.;dorsal  phar.element  ±uniform, slighter  Onchium  Cobb  1920 
Oesoph.  glands  not  prominent;  dorsal  pharyng.  element  not  uniformly  thick,  but  heavy 

Tooth-like  thickening  parallel  to  axis Camacolaimus  de  Man  1889 

(  =  Digitonchus  Cobb  1920 
=  Acontiolaimus  Fil.  1918) 
Tooth-like  thickening  bent  outward  from  beginning  of  vestibule 

Point  of  "onchium"  single Acmaeolaimus  Fil.  1918 

Point  of  Y-shaped  "onchium"  duplex Ypsilon  Cobb  1920 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  463 

Dorsal  pharyngeal  wall  not  thickened;  onchium  a  distinct  projection  (from  preceding  page) 
Cephalic  setae  20-30;  cardiac  glands  conspicuous 
Male  supplementary  organs  complex;  copulatory  muscles  conspicuous  ....  Xanthodora  Cobb  1920 

Ceaha!icPIetementS  Simp    '  PaPilloid:  copulatory  muscles  not  conspic.  Acanthopharynx  Marion  1870 
Head  with  elaborately  ornate  calvarium;  striae  0;  spinneret  present  .......  Deontostoma  Fil.  1916 

Head  without  calvarium;  cuticular  pores  absent 

Plate  round.with  "bent"  amph.;phar.smaU;ceph.set.4,cerv.oft  long.many  Diplopeltis  Cobb  1905 

(=Dipeltis  Cobb  1891 

„.  A  =  Discophora  Villot  1875) 

Plate  absent;  pharynx  large,  complex,  of  more  than  1  chamber;  onchium  large,  sharp 
Onchium  conoid  to  base  of  short  stylet;  pharynx  iquadrate;  d"  supplements  eurystomoid 
Long  cervical  setae  ±30;  <?  supplements  weakly  developed  .......  .          ,  .  .  .  Ledovitia  Fil.  1927 

Long  cervical  setae  0 

Tail  rounded;  spinneret  oft  present;  d1  supplements  well  developed..  .Eurystomina  Fil.  1921 

(  =  Eurystoma  Marion  1870 

=Marionella  Cobb  1922) 

Tail  spicate;  spinneret  0;  d"  supplements  weakly  developed  ......  Pareurystomina  Micol  1930 

Onchium  a  long  stylet;  phar.  much  deeper  than  wide;  d1  an  enchelid 
Oesophageal  bulbs  5-8,  serial,  contiguous  .........................  Polygastrophora  de  Man  1922 

Oesophageal  bulbs  0 
Anterior  oesophagus  (pharynx  ?)  narrower,  lumen  wide  ...........  Calyptronema  Marion  1870 

(  =  Catalaimus  Cobb  1920) 
Anterior  oesophagus  not  differentiated 

Vestibule  set  off  by  row  of  "commas,"  pharyng.  rings  3;  eyes  0  Symplocostomella  Micol.  1930 
Vestibule  set  off  by  rows  of  denticles  or  markings,  or  by  a  ring 
Pharyngeal  chambers  behind  vestibule  more  than  2  .............  Symplocostoma  Bast.  1865 

Pharyngeal  chambers  behind  vestibule  2;  eyes  2  ........................  Dilaimus  Fil.  1927 

(  =  Amphistenus  Marion  1870) 

-  Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both  (for  alternative  see  page  461) 
^-  Amphid  not  known  or  obscure  (for  alternative  see  next  page) 
Female  not  known 

Habitat  soil;phar.tubular,i  neck;onch.outward-acting;oes.dorylaimoid;spinneret  0  Nanonema  Cobb  1905 

(  =  Cephalonema  Cobb  1893) 

Habitat  marine;  pharynx  not  over  ,'„  neck-length;  spinneret  present  (Rhinonema?) 
Pharyngeal  bulb  stronger  dorsad;  onchium  pharyngeal;  cephalic  setae  small  or  0.  .  ..lotadorus  Cobb  1920 

Pharyngeal  bulb  absent;  onchium  a  mere  prod  at  lips;  cephalic  setae  6  .........  (Rhinonema  Allgen  1927) 

""  Female  known 
Ovary  1 

Gonad  9  outstretched  ;spinneret  pres.;wings  10,  marks  V-shaped;ceph.set.4;marine  (Nudora  Cobb  1920) 
Gonad  9  reflexed;  spinneret  absent;  not  marine 
Onchium  (spear)  bent  dorsad  at  tip;  amphid  small,  oval,  at  lips;  in  soil  ......  (Campydora  Cobb  1920) 

Onchium  not  bent  obliquely  at  tip 
Cardiac  bulb  not  valvate;  median  bulb  strong 

Tooth  recurved  outward;  long,  striae  present;  c?  supplements  papilloid.  .Diplogaster  M.  Schultze  1857 
Tooth  forward-pointing,  deepset;  long,  striae  none;  d"  supplements  setose  ----  Acrostichus  Rahm  1928 

Cardiac  bulb  valvate;  median  bulb  absent,  oesophagus  cephaloboid 
Posterior  pharynx  muscular,  lumen  closed;  vulva  ±75%;  tail  ±blunt  ........  Plectonchus  Fuchs  1930 

Posterior  pharynx  ±open;  vulva  53-65%;  tail  conoid,  usually  slender 
Vagina  directed  inward,  not  heavily  muscular;  not  viviparous  ...........  Macrolaimus  Maupas  1900 

Vagina  directed  forward,  heavily  muscular;  viviparous  or  ovoviviparous  ......  Turbatrix  Peters  1927 


'  Ovaries 

Gonads  9  outstretched  ;  pharyngeal  bulb  ±globular  ...........................  (Bolbolaimus  Cobb  1920) 

(=BUlbopharyngiella  Allgen  1929) 
—  -  Gonads  9  reflexed,  exc.  perhaps  Demaniella. 


. 

Spinneret  absent;  oesophagus  with  muscular  median  bulb,  usually  valvate 
Cardiac  bulb  valvate 

(  =  Diploscapteroides  Rahm  1928) 


Lip  region  not  set  off;  odontia  absent Poikilolaimus  Fuchs  1930 

Lip  region  set  off  by  constriction;  curved  odontia  2  or  4 Rhabditis  Duj.  1845 


Cardiac  swelling  not  valvate,  oesophagus  diplogastroid 
Onchium  small,  anterior;  median  bulb  wide  as  long,  wider  than  oesophagus  Neodiplogaster  Cobb  1924 
Onchia  larger,  basal;  "prod"  at  lips;  median  bulb  not  wider  than  oesophagus  Demaniella  Steiner  1914 

(  =  Demania  Steiner  1914) 
-  Spinneret  present;  oesophagus  without  median  bulb;  wings  often  present;  marine  exc.  Punctodora 

Lip  reg.  protrusile;  ceph.  set.  4;  renette  long;  excretory  pore  opp.  pharynx.  .Ptycholaimellus  Cobb  1920 
— Lip  region  not  protrusile 

Pharyngeal  swelling  stronger  dorsad;  d*  supplements  chromadoroid  exc.  Odontonema 

Striae  altered  laterally;  onchium  large,  dorsal,  apex  ventral Hypodontolaimus  de  Man  1886 

Striae  not  altered  laterally 

Onchium  solid,  inward-pointing Prochromadora  Fil.  1922 

Onchium  with  internal  cavity,  forward-pointing 

Tooth  small . .V. Chromadorita  Fil.  1922    f 

Tooth  very  large,  apex  ventral;  d"  supplements  papilloid Odontonema  Fil.  1930 

—Pharyngeal  swelling  not  stronger  dorsad 

Cardiac  bulb  long,  2-  or  3-parted;  striae  altered  laterally;  tooth  large,  forward-pointing 

The  bulb  with  dilated  lumen Spilopharella  Fil.  1918 

The  bulb  with  lumen  not  dilated;  d1  supplements  chromadoroid Chromadorissa  Fil.  1917 

Cardiac  bulb  short,  not  divided 

Striae  altered  laterally,  several  rows  of  dots  larger Chromadora  Bast.  1865   — 

Striae  not  altered  laterally 

Onchium  solid,  inward-pointing;  d"  supplements  chromadoroid Prochromadora  Fil.  1922 

Onchium  with  internal  cavity,  forward-pointing 

Tooth  small,  sharp;  d"  supplements  chromadoroid Chromadorita  Fil.  1922  r 

Tooth  large,  irregularly  rectangular;  cardiac  bulb  very  large,  simple Punctodora  Fil.  1930 


464  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Amphid  known  (for  alternative  see  preceding  page) 
External  amphid  not  spiral,  circular  nor  elliptical,  but  a  transverse  slit 
Female  not  known;  amphid  large 

Pharyngeal  bulb  not  stronger  dorsad;  ceph.  set.  10;  cutic.  "basket-work"  on  neck  Nygmatonchus  Cobb  1933 
Pharyngeal  bulb  stronger  dorsad;  striae  of  dots 

Denticles  in  pharynx  numerous;  cephalic  setae  4;  in  humus  near  sea  coast Denliculella  Cobb  1933 

Denticles  0;  cephalic  setae  if  present  almost  invisible;  marine lotadorus  Cobb  1920 

Female  known 

Ovary  1,  reflexed;  habitat  soil  about  roots 
Tooth  short,  closed,  not  bent  at  tip;  ovary  anterior,  vulva  57%;  spinneret(?)  present  Oionchus  Cobb  1913 

Tooth  (spear)  bent  obliquely  dorsad  at  tip  when  extruded;  spinneret  absent Campydara  Cobb  1920 

Ovaries  2,  reflexed;  spinneret  present 

Oesophageal  bulbs  5-8,  contiguous ;  amphid  with  pocket ;  c?  supplements  eurystomoid  Bolbella  Cobb  1920 
Oesophageal  bulbs  not  more  than  2,  not  contiguous 

Tooth  small,  near  lips;  setae  0;  pharynx  long,  tubular;  in  fresh  water Rhabdolaimus  de  Man  1880 

Tooth  not  small;  pharynx  ±1  head- width  deep;  amphid  usually  at  lips 

Onchium  curved,  solid,  apparently  mobile  radially Prochromadara  Fil.  1922 

Onchium  forward-pointing  or  irectangular,  motion  apparently  iparallel  to  axis 
Lipreg.  protrusile;  ceph.  set.  4 ;  renette long ;  excretory  poreopp.  pharynx.. Ptycholaimell us  Cobb  1920 
Lip  region  not  protrusile 

Neck  with  cuticular  "basket-work";  4  sublat.  scales  opp.  phar.;  spicula  2  sections  Rhips  Cobb  1920 
Neck  without  "basket-work,"  or  laterally  only ;  scales  0;  spicula  entire 
Striae  of  rod-like  elements,  exc.  towards  extremities,  changing  to  large  dots  laterally 

Cardiac  bulb  broad,  well  set  off,  valvate Punctodora  Fil.  1930 

Cardiac  bulb  not  very  broad,  confluent,  non- valvate Neochromadora  Micol.  1924 

Striae  of  dots,  altered  laterally 

Pharyngeal  bulbstrongerdorsad;onch.large;card.bulb2-3-zoned  . .  Hypodontolaimus  de  Man  1886 
Pharyngeal  bulb  if  present  not  stronger  dorsad;  cardiac  bulb  not  zoned. . .  .Chromadora  Bast.  1865' 
External  amphid  spiral,  circular  or  elliptical 

Female  not  known;  marine  or  salt  marsh  (exc.  Amphispira  ?) ;  wings  none 

Habitat  soil  (possibly  marine) ;  amphid  spiral;  cephalic  setae  0;  spinneret  present  Amphispira  Cobb  1920 
Habitat  marine  or  salt  marsh 
Amphid  multispire,  large,  on  front  curvature  of  head 

Striae  altered  laterally Neotonchus  Cobb  1933 

Striae  not  altered  laterally Amphispira  Cobb  1920 

Amphid  not  multispiral 

Onchium  spear-like,  free  at  tip Oistolaimus  Ditlev.  1921 

(cf.  Onyx  Cobb  1891) 
Onchium  not  spear-like 

Cephalic  setae  minute;  pharyng.  bulb  stronger  dorsad;  amphid  narrow,  transverse  lotadorus  Cobb  1920 
Cephalic  setae  0;  amphid  circular  or  monospiral 

Tooth  ventral Crassolaimus  Kreis  1929 

Tooth  dorsal;  nema  cephalated  by  expansion  and  by  cessation  of  striae Micromicron  Cobb  1920 

—  Female  known 
Ovary  1 

Gonad  9  outstretched;  amphid  circular;  cephalic  setae  4;  spinneret  present;  marine 
Wings  10,  of  V-shaped  marks;  phar.  bulb  long,  set  off  by  constrict. ;  lab.  papill.  setose  Nudora  Cobb  1920 
Wings  0;  phar.  bulb  very  slight;  labial  papillae  0;  renette  large,  of  ±6  cells Synonema  Cobb  1920 


Habitat  not  marine;  amphid  round  or  oval;  spinneret  m 
Median  oesophageal  bulb  present,  usually  valvate;  tail 
Pharynx  narrow,  post,  part  6  times  width;  ceph.  set.  0;  < 


Habitat  marine;  amphid  round;  spinneret  pres.;  wings  6-20,  marks  V-shaped  Monoposthia  de  Man  1889 

none  exc.  Udonchus 
il  conoid,  then  setaceous;  bursa  none 
;  onch.  small,  basal  Diplogasteroides  de  Man  1912 
Pharynx  not  more  than  twice  as  deep  as  wide;  cephalic  setae  usually  present 

Onchium  anterior,  recurved,  outward-acting Diplogaster  M.   Schultze  1857 

Onchium  deepset,  forward-pointing Acrostichus  Rahm  1928 

Median  oesophageal  bulb  absent;  striae  fine,  plain 

Pharynx  occupying  i  neck-length;  habitat  decaying  bulbs (Odontopharynx  de  Man  1912) 

Pharynx  occupying  J  neck-length  or  less 

Tooth  (spear)  bent  obliquely  dorsad  at  lips  when  extruded;  soil  near  roots. .  (Campydara  Cobb  1920) 
Tooth  not  bent 

Spinneret  present;  external  amphid  oval;  pharyng.  bulb  absent;  in  fresh  water  Udonchus  Cobb  1913 
Spinneret  absent;  amphid  circular 

Pharyngeal  swelling  absent;  cardiac  bulb  valvate Macrolaimus  Maupas  1900 

Pharyngeal  swelling  clavate;  in  moist  soil Odontolaimus  de  >Ian  1880 

(  =  Neonchus  Cobb  1893) 
Ovaries  2 

Gonads  9  outstretched;  spinneret  present;  habitat  marine  or  brackish  soil 
Amphid  not  multispire;  onehia  several,  often  minute 
Pharyngeal  bulb  none,  or  slight,  confluent;  ceph.  setae  4;  labial  papillae  6.  .Microlaimvs  de  Man  1880 

Pharyngeal  bulb  almost  globular;  cephalic  setae  6;  labial  setae  6 (Bolbolaimus  Cobb  1920) 

(=Bulbopharyngiella  Allgen  1929) 
Amphid  multispire;  striae  finely  dotted;  pharyngeal  bulb  absent 

Head  setose;  striae  not  altered  laterally;  spicula  long;  apophysis  none Comesoma  Bast.  1865 

Head  less  setose;  spicula  short;  gubernaculum  with  apophysis 

Male  ventral  pre-anal  supplementary  organs  small,  papilloid (Parasabatieria  de  Man  1907) 

Male  supplementary  organs  absent (Sabatieria  de  Rouville  1903) 

Gonads  9  reflexed 
Spinneret  absent  (for  alternative  see  next  page) 

Habitat  marine;  cephalic  setae  4;  pharyngeal  bulb  absent,  pharynx  small Spirina  Fil.  1918 

(=Spira  Bast.  1865) 
Habitat  not  marine;  tail  isetaceous  exc.  Neodiplogaster 

Cardiac  bulb  valvate Poikilolaimus  Fuchs  1930 

Cardiac  bulb  not  valvate 

Pharyngeal  bulb  clavate,  ,'0-}  neck-length ; median  bulb  none;ceph.set.lO  Odontolaimus  de  Man  1880 
Pharyngeal  bulb  none  or  short,  not  tapering;  oesoph.  diplogastroid;  onchium  a  projection 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS     465 

Median  oesophageal  bulb  not  swollen;  ceph.  set.  0;  striae  plain (Odontopharynx  de  Man  1912) 

Median  oesophageal  bulb  swollen;  cardiac  swelling  non-valvate 

Pharynx  i  wide  as  deep;  ceph  set.  present;  tail  setaceous;  bursa  0. .  ..Diplogaster  M.  Schultze  1857 
Pharynx  narrow,  posterior  tubular  portion  not  over  1  as  wide  as  deep;  ceph.  set.  0 

Onchium  basal;  tail  conoid  then  setaceous;  bursa  none Diplogasteroides  de  Man  1912 

Onchium  anterior;  striae  of  dots;  tail  conoid;  bursa  rhabditoid Neodiplogaster  Cobb  1924 

Spinneret  present,  exc.  sometimes  Spirina  (for  alternative  see  preceding  page) 

Oesophageal  bulbs  5-8,  serial,  contiguous;  cf  an  enchelid;  marine Polygastrophora  de  Man  1922 

Oesophageal  bulb  1 

Anterior  oesophagus  narrow,  lumen  wide;  marine Calyptronema  Marion  1870 

(  =  Catalaimus  Cobb  1920) 
Anterior  oesophagus  not  differentiated 
Wings  present 

Pharyngeal  bulb  set  off  by  constriction;  wings  12,  bristles  retrorse;  marine. .  .Rhinema  Cobb  1920 
Pharyngeal  bulb  none  or  confluent 

Nema  cephalated  by  cuticular  change  &  ±  by  expansion;  cardiac  bulb  short,  not  divided 
Head  "punctate" ;  wings  12-18;  ceph.  set.  6;  denticles  pres. ;  amph.  spiral  Desmodorella  Cobb  1933 
Head  plain;wing  l;ceph.set.0;denticles  0;amph.round;caud.gl'nds  pre-anal  Xenonema  Cobb  1920 
Nema  not  cephalated;  cardiac  bulb  long,  2-  or  3-zoned;  amphid  spiral 

Striae  of  dots;  wings  scalariform;  cf  supplements  0 Spilophorium  Cobb  1933 

(-SpOopkom  Bast.  1865) 
Striae  plain 

Cephalic  setae  many,  jointed;  c?  pre-anal  cuticle  thickened Neonyx  Cobb  1933 

Cephalic  setae  4,  short;  wing  1;  cf  supplements  post-anal Metachromadara  Fil.  1918 

(  =  Ckromadoropsis  Fil.  1918) 

Wings  0;  striae  not  altered  laterally,  exc.  sometimes  Desmodora 
Habitat  freshwater;  minute  subordinate  onchia  usually  present 

Pharynx  behind  onchia  ±  parallel-sided;  pharyngeal  bulb  definite Elhmolaimus  de  Man  1880 

Pharynx  behind  onchia  iconoid;  pharyngeal  bulb  absent 

Amphid  spiral;  cephalic  setae  usually  10;  pharynx  open,  irregular Achromadora  Cobb  1913 

Amphid  circular;  cephalic  setae  4;  pharynx  often  obscure Prodesmodara  Micol.  1923 

Habitat  marine 
Dorsal  pharyngeal  wall  thickened,  onchium-like;  amphid  monospire 

at  lips;  cephalic  setae  4;  renette  far  back 

Oesoph.  glands  obscuring  junction  of  intest.;  dorsal  phar.  element  iuniform  Onchium  Cobb  1920 
Oesoph.  glands  not  prominent;  dorsal  pharyng.  element  not  uniformly  thick,  but  heavy 

Tooth-like  thickening  parallel  to  axis Camacolaimus  de  Man  1889 

(  =  Digitonchus  Cobb  1920 
=  Acontiolaimus  Fil.  1918) 
Tooth-like  thickening  bent  outward  from  beginning  of  vestibule 

Point  of  "onchium"  single Acmaeolaimus  Fil.  1918 

Point  of  Y-shaped  "onchium"  duplex Ypsilon  Cobb  1920 

Dorsal  pharyngeal  wall  not  thickened;  onchium  a  distinct  projection 
Cephalic  setae  12-26;  cardiac  bulb  elongate;  amphid  spiral 

Striae  of  dots,  on  head  also;  labial  papillae  setose;  ceph.  set.  12 Bradylaimus  Stekhoven  1931 

Striae  plain,  absent  on  head;  cephalic  setae  24-26;  amphid  monospire 

Pharynx  denticulate;  onch.  sigmoid  ventrally ;  of1  supplements  sigmoid  Sigmophora  Cobb  1933 
Pharynx  not  denticulate;  onch.  not  sigmoid;  cf  supplements  papilloid  Xanthodora  Cobb  1920 
Cephalic  setae  4 
Striae  of  dots 

Dorsal  onchium  large,  basal;  pharyngeal  bulb  stronger  dorsad Odontonema  Fil.  1930 

Dorsal  onchium  anterior;  pharyngeal  bulb  isymmetrical Chromadorina  Fil.  1918 

Striae  plain 

Head  set  off  by  lack  of  striae;  pharynx  &  onchium  inconspic. ;  marine. .  Desmodora  de  Man  1889 
Head  not  set  off;  striae  extending  to  lips 

Pharyngeal  bulb  0;  cardiac  bulb  short;  onchium  minute;  neck  6-7% Spirina  Fil.  1918 

(=Spira  Bast.  1865) 
Pharyngeal  bulb  present;  cardiac  bulb  long,  massive,  2-  or  3-zoned;  neck  over  12% 

Onchium  spear-like;  head  rounded Onyx  Cobb  1891 

Onchium  not  spear-like;  head  truncate Metachromadora  Fil.  1918 

(  =  Chromadoropsis  Fil.  1918) 

Teeth  (onchia  or  odontia)  2  or  more  (for  alternative  see  page  461) 

Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both  (for  alternative  see  page  467) 
The  teeth  ±equal  in  size,  usually  mobile  radially  (for  alternative  see  next  page) 
Stroke  of  teeth  outward;  amphid  often  obscure  (for  alternative  see  next  page) 
Spinneret  absent;  '9  or  '  9 ' 

Cardiac  bulb  valvate;  cuticle  without  longitudinal  striae Diploscapter  Cobb  1913 

Cardiac  bulb  not  valvate,  median  bulb  valvate;  cuticle  with  longitudinal  striae 

Posterior  pharyngeal  chamber  behind  onchia;  lips  with  radiate  framework Mononchoides  Rahm  1928 

Posterior  pharyngeal  chamber  absent;  lips  without  radiate  framework Diplogaster  M.  Schultze  1857 

(=Pristionchus  Kreis  1932) 

Spinneret  present;  median  oesophageal  bulb  absent 
Pharynx  tubular,  4-6%  of  body  length 

Amphid  long,  reaching  base  of  pharynx  or  mid-body ;  odontia  6,  minute ;  -  9  ~ Pseudolella  Cobb  1920 

Amphid  small,  at  lips,  with  pocket;  odontia  3,  massive;  tail  oft  striate; '  9 ' Syringolaimus  de  Man  1888 

Pharynx  conoid,  not  over  2%  of  body  length 

Odontia  0  ;onch .  3 ,  at  base  shallow  phar.  ;amph .  round ;  card,  swelling  obvious  r  9  A ponchium  Cobb  1920 
Odontia  6  or  12;onch.  0;amph.  bent  or  crook-shape;card.  bulb  0  or  weakr9~  Odontophora  Butech.  1874 

(  =  Trigonolaimus  Ditlev.  1918 
=  Conolaimus  Fil.  1918) 
Striae  of  dots;  cardiac  swelling  obvious 

Amphid  spiral  ;onch.3,curved;  cf1  supplements  0  or  papilloid;  gubernac.O;  cf  only. .  Statenio  Allgen  1930 
Amphid  a  transverse  slit,  near  lips;  '  9 ' 

Lateral  fields  marked  by  longitudinal  rows  of  larger  dots Chromadorella  Fil.  191: 

Lateral  fields  without  longitudinal  rows  of  larger  dots Prochromadorella  Micol.  1924 


466  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Stroke  of  teeth  inward;  amphid  occasionally  obscure  (for  alternative  see  preceding  page) 
Spinneret  0;  phasmids  present;  odontia  6;  oesophagus  cephaloboid;  ovaries  reflexed 
Nema  usually  cephalated;  cirri  0;  amphid  round;  soil  &  fresh  water; '?'... .  (Teratocephalus  de  Man  1876) 

Nema  not  cephalated;  cirri  6;  amphid  oval;  tail  hooked;  in  bark,  etc.;  '9 (Chambersiella  Cobb  1920) 

(  =  Diastolaimus  Rahm  1928) 
Spinneret  present 
Mandibular  jaws  2  or  3;  pharyngeal  and  cardiac  bulbs  strong;  marine 

Jaws  3;  amphid  not  known;  c?  only Fusonema  Kreis  1928 

Jaws  2,  lateral,  dentate;  amphid  multispire Cheironchus  Cobb  1917 

(  =  DignathonemaFil.  1918) 
Mandibular  jaws  absent 
Amphid  multispire;  lips  flat,  confluent;  pharynx  rather  narrow;  marine 

Striae  very  fine;  wings  0;  labial  papillae  not  seen;  d"  only (Alaimonema  Cobb  1920) 

Striae  icoarse,  of  dots;  wings  pres.;  labial  papillae  12;  -?-,  or  reflexed  at  tip  (Mesonchium  Cobb  1920) 

(  =  Pepsonema  Cobb  1920) 
Amphid  not  multispire 

Habitat  soil;amph.monospire  to  crook-shape ;phar.  6%;nema  small,0.2  mm.;J  (Pycnolaimus  Cobb  1920) 
Habitat  marine;  pharynx  under  2%,  not  tubular;  ovaries  not  reflexed 

Vulva  15%;  odontia  12,  minute;  amphid  "folded";   9~ Synodontium  Cobb  1920 

Vulva  81%;  odontia  0;  onchia  3;  pharyngeal  swelling  slight;  ~9 (Aponchium  Cobb  1920) 

The  teeth  ±unequal  in  size,  usually  not  mobile  radially;  amph.  usually  not  obscure  (from  preceding  page) 
External  amphid  not  spiral,  circular  nor  elliptical;  ovaries  2;  spinneret  present 

Gonads  9  outstretched ;amph.  long,  reaching  sometimes  to  mid-body  ;odontia6r?~Psei«ioW/a  Cobb  1920 
Gonads  9  reflexed;  amphid  a  transverse  slit 

Striae  fine,  plain;  onchia  dorsal  and  ventral Deltanema  Kreis  1929 

(cf.  Metalinhomoeus  de  Man  1907) 

Striae  resolvable  into  elements;  dorsal  onchium  usually  the  largest 
Spicula  of  2  joints;  striae  forming  "basket-work"  on  neck;  amphid  opp.  base  pharynx  Rhips  Cobb  1920 

Spicula  entire;  striae  of  dots ;  amphid  near  lips Chromadora  Bast.  1865  — 

External  amphid  spiral,  circular  or  elliptical 
Female  not  known;  spinneret  present;  marine 

Amphjd  multispire ;head  conoid;onch.  minute;ceph.  &  subceph.  setae  in  sets  of  4  Alaimonema  Cobb  1920 
Amphid  circular,  elliptical  or  monospiral 

Pharynx  surrounded  at  base  by  cuticularized  ring Cricolaimus  Southern  1914 

Pharynx  not  surrounded  by  cuticularized  ring 

Striae  of  dots,  interrupted  laterally;  pharynx  cyatholaimoid,  onchium  large Endolaimus  Fil.  1922 

Striae  unaltered  laterally;  pharynx  small;  cf  supplements  tubular,  post-anal Catanema  Cobb  1920 

Female  known 
Ovary! 

Gonad  9  outstretched ;spinneret  pres.  ;cf  supplements  numerous,complex;marine  Aponchium  Cobb  1920 
Gonad  9  reflexed;  amphid  small,  circular,  obscure;  spinneret  0;  not  marine 

Cardiac  bulb  valvate,  median  bulb  absent;  bursa  small,  ribs  stout Myolaimus  Cobb  1920 

Cardiac  bulb  not  valvate;  oesophagus  idiplogastroid 

Oesophagus  without  (or  with  non-valvate,  clavate)  median  swelling Odontopharynx  de  Man  1912 

Oesophagus  with   median  valvate  bulb Diplogaster  M.   Schultze  1857 

(=Pristionchus  Kreis  1932) 
Ovaries  2 
Gonads  9  outstretched,  Mesonchium  reflexed  at  tips;  marine 

Amphid  spiral;  dots  larger  laterally;  onchia  ±equal;  spinneret  present (Mesonchium  Cobb  1920) 

(=Pepsonema  Cobb  1920) 

Amphid  circular;  striae  when  present  not  altered  laterally;  onchia  unequal 

Striae  desmodoroid,  coarse,  plain;  amph.  behind  pharynx,  open  caudad  Paracothonolaimus  Schulz  1932 
Striae  none,  or  not  desmodoroid 

Pharyngeal  bulb  iglobular,  set  off  by  constriction;  spinneret  present Bolbolaimus  Cobb  1920 

(=Bulbopharyngiella  Allgen  1929) 

Pharyngeal  swelling  slight,  confluent;  base  of  pharynx  denticulate Linhomoeus  Bast.  1865 

(i.e.  subg.  Eulinhomoeus  de  Man  1907) 
Gonads  9  reflexed  (Mesonchium  at  tips  only) 
Habitat  marine;  spinneret  present;  amphid  spiral 
Striae  of  dots;  amphid  opposite  pharynx,  of  few  winds 
Subventral  onchium  small,  dorsal  acting  out;  dots  unaltered  laterally. ..  .Chromadorina  Fil.  1918 

Subventral  &  dorsal  onchia  dhequal,  apices  axial;  dots  larger  laterally Mesonchium  Cobb  1920 

(=Pepsonema  Cobb  1920) 
Striae  none  or  plain 

Head  set  off  by  cessation  of  coarse  annulation ;  amphid  usually  multispire . . .  Desmodora  de  Man  1889 
Head  not  set  off;  striae  none  or  very  fine 

Male  ventral  pre-anal  supplements  tubular,  sigmoid,  in  2  rows Polysigma  Cobb  1921 

Male  ventral  pre-anal  supplements  simple,  in  1  row Chromaspirina  Fil.  1918 

(=Mesodorus  Cobb  1920) 
Habitat  not  marine 

Spinneret  present;  amphid  spiral,  behind  pharynx;  in  fresh  water Achromadora  Cobb  1913 

Spinneret  absent;  phasmids  present;  amphid  circular;  usually  in  soil 

Cardiac  bulb  valvate,  oesophagus  cephaloboid;  onchia  4 Seleneella  Rahm  1932 

Cardiac  bulb  not  valvate;  oesophagus  diplogastroid 

Anterior  oesophagus  (corpus)  without  (or  with  clavate,  non-valvate)  swelling 
Cephalic  setae  6  or  10;  dorsal  onch.  opposed  by  ventral  onchium  or  ridge. . .  .Butlerius  Goodey  1929 

Cephalic  setae  6;  dorsal  onchium  opposed  by  denticles Odontopharynx  de  Man  1912 

Anterior  oesophagus  (corpus)  ending  in  ±  valvate  median  bulb 
Lips  with  radiate  framework;  post,  pharyngeal  chamber  behind  onchia. .  .Mononchoides  Rahm  1928 

Lips  without  radiate  framework;  post,  pharyngeal  chamber  none Diplogaster  M.  Schultze  1857 

(  =  Pristionchus  Kreis  1932) 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  467 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling  (for  alternative  see  page  465) 
The  teeth  ±equal  in  size,  usually  mobile  radially  (for  alternative  see  next  page) 
Stroke  of  teeth  outward;  amphid  usually  not  obscure 

External  amphid  spiral,  circular  or  elliptical;  spinneret  present  (Eleutherolaimus  ?) 
Armature  of  2  teeth ;ceph.  set.  4  ;amph.  monospire.in  front  of  setae;d"  only  Diodontolaimus  Southern  1914 
Armature  of  6  or  12  odontia 

Odontia  3-jointed, heavy  ;phar.  cylind.;onch.  dorsal  ;am ph.  round-multispire;  ~9  Scaptrella  Cobb  1917 
Odontia  not  jointed 

Amphid  "folded"  or  shepherd's  crook;  ~9~ Odontophora  Butsch.  1874 

(  =  Trigonolaimus  Ditlev.  1918 
=  ConolaimusFil.  1918) 

Amphid  circular  or  elliptical,  sometimes  obscure;  cephalic  setae  4 

Pharynx  obscure;  odontia  small;  lab.  set.  6,  setae  long;  striae  coarse;  '  9 '  Stephanolaimus  Ditlev.  1918 
Pharynx  obvious;  odontia  larger;  labial  and  subcephalic  setae  0;  cf  only 

Striae  of  dots;  amphid  transverse,  open  caudad Apodontium  Cobb  1920 

Striae  plain;  amphid  circular Eleutherolaimus  Fil.  1922 

External  amphid  not  spiral,  circular  nor  elliptical;  spinneret  pres.  exc.  Ironus  and  Parironus 
Cardiac  bulb  slight ;  striae  of  dots ;  amphid  a  transverse  slit  near  lips ;  '  9  ' 

Dots  of  striae  larger  laterally,  in  longitudinal  rows (Chromadarella  Fil.  1918) 

Dots  of  striae  not  altered  laterally (Prochromadorella  Micol.  1924) 

Cardiac  bulb  none;  striae  none,  or  plain  and  very  fine 
Odontia  6,  sometimes  dentate;  amphid  ±"folded"  or  crook-shaped;  ~9~ 

Amphid  opposite  basal  portion  of  pharynx;  odontia  less  developed Axonolaimus  de  Man  1889 

Amphid  opposite  anterior  portion  of  pharynx;  odontia  more  developed Odontophora  Butsch.  1874 

(  =  Trigonolaimus  Ditlev.  1918 
=  ConolaimusFil.  1918) 
Odontia  or  onchia  3;  amphid  transverse,  with  internal  pocket;  ovaries  reflexed 

Armature  3  awl-shaped  onchia,  protrusile  forward;  pharynx  0.5%;  '  9 ' (Fimbrilla  Cobb  1905) 

(  =  Fimbria  Cobb  1894) 
Armature  3  heavy  odontia;  pharynx  tubular,  l-4( :'c;  Ironinae 

Lips  expanded,  denticulate,  6;  tail  2% ;  spinneret  ventrad;  9  ' Trissonchulus  Cobb  1920 

Lips  not  expanded;  tail  5%  or  more;  spinneret  not  ventrad;  '  9  ' 

Spinneret  none;  pharynx  2-4%;  dorsal  tooth  duplex;  in  fresh  water  and  soil Ironus  Bast.  1865 

Spinneret  present  (in  Parironus  rudimentary  or  none);  marine 
Cephalic  setae  0  or  papilloid;  odontia  not  duplex;  pharyngeal  swelling  slight 

Pharyngeal  wall  thin;  pharynx  3%;  nema  3  mm Dolicholaimus  de  Man  1888 

Pharyngeal  wall  thick;  pharynx  1.1%;  nema  2-7  mm Thalassironus  de  Man  1889 

Cephalic  setae  present 
Odontia  duplex;  phar.  2.7%,  bulb  set  off  by  constriction;  ceph.  set.  6,subceph.4../roneifa  Cobb  1920 

Odontia  not  duplex;  pharynx  1-1.6%,  swelling  slight;  cephalic  setae  10 Parironus  Micol.  1930 

Stroke  of  teeth  inward;  amphid  known,  in  Enoplidae  with  internal  pocket  and  often  obscure 
External  amphid  not  spiral,  circular  nor  elliptical;  ovaries  reflexed 

Ovary  1,  post.;  phar.  bulb  strong;  "palps"  labial  ;onch.  3,  at  summit  of  apophyses  Gammanema  Cobb  1920 
Ovaries  2;  wings  absent;  amphid  with  internal  pocket;  Enoplidae 

Calvarjum  a  band  with  undulating  margins;  glands  lateral;  odontia  large Fiacra  Southern  1914 

Calvarium  absent 

Onchia  3,  awl-like,  protrusile  forward,  like  bristles  around  open  mouth Fimbrilla  Cobb  1905 

(  =  Fimbria  Cobb  1894) 
Onchia  not  awl-like 
Lips  confluent,  bearing  6  (or  3  duplex)  odontia 

Pharynx  narrow;  onchia  0;  odontia  probaby  6 Tubolaimella  Cobb  1933 

Pharynx  conoid;  onch.  3,  midway ,  alternating  paired  odontia . .  Rhabdodemania  Baylis  &  Daubney  1926 

(  =  Demania  Southern  1914) 
Lips  distinct,  3;  armature  heavy 
The  lips  large,  conoid,  as  high  as  broad;  jaws  3 

Mandibles  2-clawed;  lips  radially  striate;  spicula  long,  striate Enoploides  Saveljev  1912 

Mandibles  absent;  lips  not  striate;  tooth  midway  on  onchial  framework . . .  Enoplolaimus  de  Man  1893 
The  lips  not  conoid,  nor  as  high  as  broad 
Armature  3  short  flattish  acute  onchia,  doming  the  ismall  pharynx ....  Triodontolaimus  de  Man  1893 

Armature  of  3  jaws  within  the  pharynx,  anteriorly  2-pointed Enoplus  Duj.  1845 

(  =  Enoplostoma  Marion  1870) 
External  amphid  spiral,  circular  or  elliptical 
Female  not  known 
Amphid  monospire,  transverse;  lips  4;  cephalic  setae  4;  c?  supplements  8-12,  tubular 

Striae  very  fine;  pharynx  conoid;  onchia  3;  labial  papillae  2 Dagda  Southern  1914 

Striae  coarse;  phar.  cylind.;  onch.  2,  lateral  orsubventral;  lab.  papill.  4  Diodontolaimus  Southern  1914 
Amphid  multispire;  d*  supplements  ichromadoroid 

Pharynx  unarmed;  lips  6,  grasping  organs,  with  longitudinal  cuticular  ribs Dispira  Cobb  1933 

Pharynx  armed,  bulb  strong;  often  nemativorous;  cf  supplements  chromadoroid 
Mandibles  3,  split  exc.  at  tips,  distal  hooks  3,  subordinates  2;  phar.  1  chamber.  .Synonchium  Cobb  1920 
Mandibles  0;  phar.  2  chambers;  onchia  3,  midway,  with  backward  apophyses. .  Trogolaimus  Cobb  1920 
Female  known 

Ovary  1 ;  amphid  circular  or  monospiral  (for  alternative  see  next  page) 

Gonad  9  post.;pnch.3,  on  apophyses ;phar.bulb  strong ;spinneret  pres.;marine  Gammanema  Cobb  1920 
Gonad  9  anterior 
Spinneret  none;  wings  none;  labial  "palps"  6,  small;  marine;  ~9 

Amphid  large,  raised  centrally;  tail  with  thorn-like  setae (Zanema  Cobb  1920) 

Amphid  small,  not  projecting;  tail  without  setae (Crystallonema  Cobb  1920) 

Spinneret  present 
Cephalic  setae  usually  0  or  papilloid;  ovoviviparous  or  viviparous;  in  gills  of  land  crabs 

Pharynx  small,  of  2  chambers;  cephalic  setae  10,  often  papilloid. (Monhystrium  Cobb  1920) 

Pharynx  large,  open,  of  1  chamber;  cephalic  setae  0;  wings  none Tripylium  Cobb  1920 

Cephalic  setae  present;  ovary  outstretched;  marine 

Lips  thick,  with  3  projecting  finger-like  "odontia";  wings  up  to  32  on  head (Xyala  Cobb  1920) 

Lips  6,  very  thin,  each  with  3  parallel-sided  cuticularized  ribs (Daptonema  Cobb  1920) 

(cf.  Theristus  Bast.  1865) 


468  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Ovaries  2  (for  alternative  see  preceding  page) 
Gonads  9  outstretched;  spinneret  present;  marine 

Amphid  "folded"  or  crook-shaped;  pharynx  conoid;  striae  plain (Axonolaimus  de  Man  1889) 

Amphid  multispire;  striae  of  dots,  altered  on  lateral  fields 

Spicula  2-jointed ;  nema  2%  wide Dorylaimopsis  Ditlev.  1918 

(  =  Xinema  Cobb  1920) 

Spicula  entire;  nema  4%  wide Mesonchium  Cobb  1920 

(  =  Pepsonema  Cobb  1920) 
Gonads  9  reflexed;  spinneret  present 

Amphid  large,  multispire;  striae  resolvable  into  elements;  often  nemativorous 
Pharynx  2  chambers;  mid-pharynx  denticulate,  apophyses  forward  &  backward;  striae  of  dots 
Circular  muscles  about  anterior  pharynx;  phar.  small;  denticles  irregular. . Cobbionema  Fil.  1922 
Circular  muscles  none;  pharynx  capacious;  denticles  regularly  placed  H alichoanolaimus  de  Man  1886 

(  =  Smalsundia  Allgen  1929) 

Pharynx  not  of  2  chambers;  denticles  absent  (Demonema  ?) 
Mandibles  none 
Dots  of  striae  not  larger  laterally;  jaws  with  many  horny  teeth  anteriorly. .  ..Demonema  Cobb  1894 

Dots  of  striae  larger  laterally;  onchia  equal,  apices  axial Mesonchium  Cobb  1920 

(  =  Pepsonema  Cobb  1920) 
Mandibles  2  or  3;  Selachineminae 

Dorsal  mandible  a  mere  rod,  developed  mandibles  2 Selachinema  Cobb  1915 

Dorsal  mandible  developed,  making  3,  ±split;  subordinate  hooks  pres. ;  cutic.  pores  pres. 
Central  mandibular  prong  1,  no.  hooks  odd ;  striae  of  dots ;  c?  supplements  2  Synonchium  Cobb  1920 
Central  mand. prongs  2,no. hooks  even;stri.dots,  dashesic?  supplements  20  Synonchiella  Cobb  1933 
Amphid  small,  opening  circular,  obscure;  lips  3,  large;  Enoplinae 

Lips  not  conoid,  nor  high  as  broad;  labial  papillae  seldom  setose;  jaws  2-pointed.  .Enoplus  Duj.  1845 

(  =  Enoplostoma  Marion  1870) 
Lips  large,  conoid,  often  as  high  as  broad;  labial  papillae  6,  setose 

Mandibles  2-clawed;  lips  radially  striate;  spicula  long,  striate Enoploidex  Saveljev  1912 

Mandibles  absent;  lips  not  striate 
Basal  onchia  large,  reaching  lips  % 

Framework  of  jaws  absent Sai-eljevia    Fil.  1927 

Framework  of  jaws  present Filipjeria    Kreis  1928 

Basal  onchia  absent;  "jaws"  3.  without  hooks 

Jaw  framework  bearing  3  equal  mid-pharyngeal  teeth Enoplolaimus  de  Man  1893 

Jaw  framework  without  teeth Parenopius  Fil.  1927 

^The  teeth  iunequal  in  size,  usually  not  mobile  radially;  amph.,  in  Enoplidae,  oft  obscure  (from  pg.  467) 
Female  not  known 

Cephalic  setae  0;  spiculum  1,  gubernaculum  absent Dioncholaimus  Kreis  1932 

Cephalic  setae  pres.;  spicula  2,  gubernac.  pres.  (Hyptiolaimus,  Cacolaimus,  Convexolaimus,  J  only) 
Amphid  multispire,  ±head  width;  striae  of  dots,  wings  2;  labial  "palps"  12,  jointed  Pomponema  Cobb  1917 
Amphid  circular,  elliptical  or  monospiral 

Pharynx  with  denticles,  or  many  subordinate  onchia ;  labial  pa  pill.  6,  setose;  amph.  round  or  oval 
Labial"palps"12,  tips  large;  onch.  dorsal,  denticles  not  basal;  wingscalariform  Anaionchium  Cobb  1920 

Labial  "palps"  0;  base  of  pharynx  filled  with  subordinate  onchia Polydontus  Schulz  1932 

Pharynx  without  denticles  or  numerous  subordinate  onchia 

Bulb  around  pharynx  set  off  by  sudden  constriction Hyptiolaimus  Cobb  1930 

Bulb  around  pharynx  none  or  not  set  off  by  constriction 

Striae  coarse;  onchia  2,  lateral  or  subventral;  labial  papillae  4 DiodonMaim  us  Southern  1914 

Striae  none  or  very  fine;  onchia  3 

Lips  4,  2  of  them  bearing  papillae;  cephalic  setae  4;  cf  supplements  tubular  .  .Dayda  Southern  1914 
Lips  6,  papillae  6,  setose;  cephalic  setae  10,  short;  J 

Head  set  off  by  thicker  cuticle;  wall  of  pharynx  thin Cacolaim us  Kreis  1932 

Head  not  set  off,  its  cuticle  thin;  wall  of  pharynx  distinct Conrexolaimus  Kreis  1928 

—  Female  known 
—  Ovary  1 ,  anterior  (Pseudoncholaimus  ?) 

Median  onchium  spear-like,  dorsal  onchium  minute,  basal Enoplocheilus  Kreis  1932 

••  Median  spear-like  onchium  absent 

Gonad  9  outstretched;  amphid  circular  or  monospiral 

Onchia  2,  like  vertical  plates, subventral;  amphid  monospire.  longer  than  wide.  .Gonimichus  Cobb  1920 
Onchia  not  plate-like,  basal,  outlets  of  oesoph.  glands;  amph.  round;  tail  isetaceous  Cobbia  de  Man  1907 
— Gonad  9  reflexed 

Spinneret  absent;  phasmids  present 

Cardiac  bulb  iglandular,  not  valvate;  median  swelling  often  present  (Odonto pharynx  de  Man  1912) 
Card,  bulb  valvate,  oes.  cephaloboid;  vagina  directed  forward,  muscles  heavy  Turbatrix  Peters  1927 

(  =  Anguillula  auctores) 

~  Spinneret  present;  phasmids  absent;  amphid  with  internal  pocket,  usually  small 
Cephalic  setae  0;  papillae  in  2  circlets;  in  soil  and  fresh  water 

Pharynx  large,  open,  d=  parallel-sided;  spinneret  terminal Mononchus  Bast.  1865 

Pharynx  narrow,  iconoid;  spinneret  ventrad Mononchulus  Cobb  1918 

: —  Cephalic  setae  present;  papillae  1  circlet;  marine  or  in  brackish  waters;  Oncholaiminae 
— •  Demanian  system  absent 

Ovary  posterior;  vulva  73-77%;  gubernaculum  none Pseudoncholaimus  Kreis  1932 

—  Ovary  ant.;  vulva  70-75%;  gubernaculum  pres.;  spicula  rttail  length. . Prooncholaimus  Micol.  1924 
Demanian  system  present 

Uvette  and  exit  pores  present Metoncholaimus  Fil.  1918 

Uvette  ampulla-like,  exit  pores  absent 

Male  with  pre-anal  appendicule Oncholaimium  Cobb  1930 

Male  without   pre-anal  appendicule Oncholaimus  Duj.  1845 

Ovaries  2 

Gonads  9  outstretched;  striae  of  rods.exc.  laterally;  amph.  a  slit.  . .  .Dicriconema  Steiner  &  Hoeppli  1926 
Gonads  9  reflexed 

Habitat  soil  and  fresh  water  (for  alternative  see  next  page) 

Spinneret  0;  anterior  oesoph.  (corpus)  with  or  without  non-valvate  med.  bulb ;  amph.  round  or  oval 
"Spear"  none;  dorsal  onch.  opposed  by  ventral  tooth  or  ridge;  ceph.  set.  6-10  . .  .Butlerius  Goodey  1929 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  469 

"Spear"  a  minute  prod  between  lips;  cephalic  setae  0  .....................  Demaniella  Steiner  1914 

(  =  .Demania  Steiner  1914) 

Spinneret  present,  exc.  sometimes  in  Mononchue 
Amphid  spiral;  pharynx  iconoid  ...........................................  Nannonchus  Cobb  1913 

Amphid  circular  or  oval,  often  small,  with  internal  pocket 
Pharynx  irregularly  conoid  ;  onchia  small  ........................................  Trilobus  Bast.  1865 

Pharynx  not  conoid;  one  or  more  onchia  large 
Lips  thick;  papillae  12,  in  2  circlets;  renette  not  known  ...................  Mononchus  Bast.  1865 

Lips  thin;  papillae  6,  ceph.  set.  10;  renette  pres.,  ampulla  conspicuous  .....  Adoncholaimua  Fil.  1908 

Habitat  marine;  spinneret  usually  present  (for  alternative  see  preceding  page) 
Cuticle  annulated 

Annules  not  resolvable  into  dots  or  rod-like  elements 

Head  truncate;  annules  interrupted;  ceph.  set.  4  ;  phar.  ribs  long.  ,  serrate  .  .  Rhabdotoderma  Marion  1870 
Head  rounded;  annules  plain;  setae  many,  short,  iirregular  on  calvarium.  .  .  .Croconema  Cobb  1920 

Annules  of  rod-like  marks;  pharynx  cyatholaimoid,  vestibule  ribbed;  amphid  a  transverse  slit 
Ceph.  set.  4,  labial  papillae  setose;  annules  plain  laterally  .....  Dicriconema  Steiner  &  Hoeppli  1926 

Ceph.  set.  10;  annules  with  V-shaped  marks  laterally,  "basket-work"  on  neck.  .  ..Rhips  Cobb  1920 

Cuticle  not  annulated;  striae  if  present  very  fine 

Head  wjth  subcuticular  calvarium;  amphid  with  internal  pocket;  Enoplidae 
Calvarium  complex,  ornate,  long-conoid  ..................................  Thoracostoma  Marion  1870 

Calvarium  relatively  simple,  a  band  with  undulating  margins;  glands  lateral 

Pharynx  wide;  lips  with  denticles;  odontia  present(?);  nema  20-34  mm..  .Cylicolaimus  de  Man  1889 
Pharynx  narrow,  ±filled  by  onchia,  dorsal  largest;  cervical  setae  many;  nema  8-17  mm. 
Odontia  present;  cephalic  setae  long  ........................................  fiacra  Southern  1914 

Odontia  absent;  cephalic  setae  short  or  medium  .............................  Synonchus  Cobb  1894 

(  =  Jagerskioldia  Fil.  1916) 
Head  without  calvarium 
Amphid  spiral;  pharynx  small,  irregularly  conoid,  vestibule  ribbed  ........  (Chromaspirina  Fil.  1918) 

(  =  Mesodorus  Cobb  1920) 

Amphid  with  internal  pocket;  pharynx  large,  open,  squarish,  ribbed  vestibule  absent 
Pharynx  not  divided,  walls  ithick;  amph.  small  ;  excretory  pore  oft  not  at  lips;  Oncholaiminae 
Demanian  system  present,  with  exit  pores  and  developed  uvette  ........  Adoncholaimus  Fil.  1918 

Demanian  system  absent,  or  gonenteric  duct  only 
Subventral  onchia  equal  in  size;  amphidial  opening  longer  than  wide 
Tail  33%,  filiform,  spinneret  none;  gubernaculum  none  .................  Filoncholaimus  Fil.  1927 

(  =  Pseiidoi>aroncholaimus  Kreis  1932) 
Tail  short,  rounded  ;  gubernaculum  present  ...............................  Pontonema  Leidy  1855 

^=Paroncholaimus  Fil.  1916) 

Subventral  onchia  unequal  in  size;  pharynx  depth  twice  its  width  or  more 

Cuticle  not  viscous;  phar.  bulb  clavate;  lip  reg.set  off  by  coastriction  .  .Steinvriella  Allgen  1932 

(  =  Steineria  Ditlev.  1928) 

Cuticle  viscous;  pharyngeal  bulb  none;  nema  under  3  mm.;  tail  6-10% 

Pharynx  very  deep,  ifilled  by  subventral  onch.;  bursa  present  Oncholaimellus  de  Man  1890 
Pharynx  not  over  twice  as  deep  as  wide,  not  filled  by  onchium;  bursa  none 
Dorsal  wall  of  pharynx  well  developed  ............................  Viscosia  (de  Man)  Fil.  1918 

Dorsal  wall  of  pharynx  rudimentary,  an  extension  of  dorsal  tooth  ----  Meroviscosia  Kreis  1932 

xcretory  pore  oft  at  lips;  large  onch.  subventral 


Pharynx  2-5  chambers,  wall  thin;  amph.  large;  exc 
Oesophageal  bulbs  5-8,  serial,  contiguous 
Amphidial  opening  transverse,  slit-like;   a"  s 


supplements  eurystomoid  ......  Bolbflla  Cobb  1920 

Amphidial  opening  ^circular;  cf  an  enchelid,  supplements  simple.  .Polygastrophora  de  Man  1922 
Oesophageal  bulbs  none 

External  amphid  transverse,  slit-like;  pharynx  usually  ±square;  caudal  glands  before  anus 
Denticles  forming  a  broad  mid-pharyngeal  band;  d"  supplements  simple.  .  .  Thoonchus  Cobb  1920 
Denticles  in  1-3  rows;   d"  supplements  complex,   "fluked"  .............  Eurystomina  Fil.  1921 

(  =  Eurystoma  Marion  1870 
=  Marionella  Cobb  1922) 

External  amphid  round;  pharynx  deep;  onch.  spear-like,  exc.  Ditlevsenella;  cf  oft  an  enchelid 
Anterior  oesophagus  narrower,  lumen  wide  ..........................  Calyplronema  Marion  1870 

(  =  Ca(aIaimiu  Cobb  1920) 
Anterior  oesophagus  not  differentiated 
Large   onchia   3  ......................................................  fenestrolaimus    Fil.  1927 

Large  onchium  1,  other  onchia  2 
The  large  onchium  conoid;  nema  4-6  mm  .............................  Ditlevsenella  Fil.  1927 

The  large  onchium  long,  slender,  spear-like 
Pharyngeal  chambers  behind  vestibule  2;  eyes  2  ..........................  Dilaimus  Fil.  1927 

(  =  Amphistenus  Marion  1870) 

Pharyngeal  chambers  behind  vestibule  more  than  2 
Chambers  separated  by  2-4  rings  or  by  dots  or  denticles  ............  Symplocostoma  Bast.  1865 

Chambers  (first  2)  separated  by  "commas";  rings  3;  eyes  6  .....  Symplocostomella  Micol.  1930 


470  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Wall  of  the  Pharynx  unarmed  (for  alternative  see  page  458) 

Cavity  not  cylindroid  nor  prismoid,  i.e.  cavity  conoid  or  irregular  in  long,  section  (for  alt.  see  page  474) 
Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both  (for  alternative  see  next  page) 
Amphid  not  known  or  obscure 
Female  not  known;  spinneret  present;  cephalic  setae  present;  nema  1%  wide;  marine 

Cuticle  with  distinct,  anastomosing  annules;  amphid  a  transverse  slit (Leptonemella  Cobb  1920) 

Cuticle  without  annules;  amphid  minute,  at  lips (Catanema  Cobb  1920) 

Female  known;  spinneret  none,  exc.  Dasylaimus 
Ovaries  2,  reflexed;  wings  present 

Spinneret  pres.;phar. denticulate ;oes. without  med. bulb ;post. ovary  undev.;marine  Do0ytotmtu  Cobb  1933 
Spinneret  0;  post,  pharynx  concave-cylind.;  oes.  with  med.  bulb;  in  sheep  dung  Rhabditoides  Goodey  1929 
Ovary  1 

Gonad  9  outstretched,  anterior;  cephalic  setae  4 Walcherenia  de  Man  1921 

Gonad  9  reflexed;  cephalic  setae  0  or  minute 

Spinneret  present;  pharynx  denticulate;  striae  of  dots;  post,  ovary  undev. :  marine  Dasylaimus  Cobb  1933 
Spinneret  0;  pharynx  not  denticulate;  oesophagus  cephaloboid;  not  marine 
Probolae  present;  amphid  at  lips;  in  soil 

Cephalic  appendages  in  2  circlets Acrobeles  Linst.  1877 

Cephalic  appendages  in  1  circlet Cephalobvs  Bast.  1865 

(  =  Acrobeloides  (Cobb)  Steiner  &  Buhrer  1933) 
Probolae  absent;  cephalic  appendages  none  or  in  1  circlet 

Pharyngeal  wall  a  long,  series  of  elements;  onch.  0;  vagina  directed  inward.  .Panagrolaimus  Fuchs  1930 
Pharyngeal  wall  not  of  serial  elements;  onch.  oft  pres. ;  vagina  directed  ±forward;  Turbatricinae 
Posterior  pharynx  closed;  vulva  ±75%;  vagina  less  muscular;  tail  iblunt. . .  .Plectonchus  Fucbs  1930 

Posterior  pharynx  ±open;  vulva  ±65%;  vagina  muscular;  tail  slender Turbatrix  Peters  1927 

(  =  Anguillula  auctores) 
Amphid  known 

External  amphid  not  spiral,  circular  nor  elliptical 
Habitat  not  marine 

Spinneret  present;  cephalic  setae  4;  in  fresh  water;  '9 Chronogaster  Cobb  1913 

Spinneret  none;  ovaries  2 

Tail  setaceous,  19%;amph.  semicirc.;oesoph.  with  med.  bulb;vulva  21%;'  9 '  (Aulolaimoides  Micol.  1915) 
Tail  not  setaceous,  9-15%;  amphid  inconspicuous,  small  or  slit-like 

Med.  oesoph.  bulb  confluent  in  front;  post.  phar.  closed;  in  decaying  matter; '  9  "...  (Cheilobus  Cobb  1924) 

(  =  Rhabdi<ophanes  Fuchs  1930) 

Med.  oesoph.  bulb  none;  pharynx  ovoid;  wings  0;  amphid  a  slit;  in  soil;  ~9~. .  .Monhystera  Bast.  1865 

(  =  M.  dintheriana  de  Man  1885) 

Habitat  marine;  cephalic  setae  present;  spinneret  present 

Ambulatory  tubes  forming  ventral  pre-anal  sole;  nema  ±S-shape,  narrowed  in  card,  reg.;  marine;  '  9 ' 
Oesoph.  region  hardly  swollen;  card,  bulb  faint;  cerv.  striae  all  alike. .  Notochaetosoma  Irwin-Smith  1918 
Oesoph.  region  swollen,  ovoid;  oesophageal  bulbs  1  or  2;  band  of  cervical 
striae  accentuated,  exc.  Tristicochaeta  falcatum 

Ventral  ambulatory  adhesion  tubes  or  setae  in  2  rows Drepanonema  Cobb  1933 

(  =  Chaetosoma  Clap.  1863) 

Ventral  ambulatory  adhesion  tubes  or  setae  in  3  or  4  rows Tristicochaeta  Panceri  1878 

(  =  Draconema  Cobb  1913) 

Ambulatory  tubes  absent;  nema  not  crooked,  not  narrowed  in  cardiac  region 

Amphid  transverse;  pharynx  minute;  annules  plain ;ceph.  set.  10,  jointed;  o*  only  Leptonemella  Cobb  1920 
Amphid  large,  folded  or  shepherd's  crook;  pharynx  obvious;  ovaries  outstretched 

Pharynx  4-5%,  heavy ,tubular;amphid  4-50%  body;ceph.set.4,subceph.l2r9~  (Pseitdolella  Cobb  1920) 
Pharynx  under  2%,  conoid,  not  heavy;  cephalic  setae  large,  long;  odontia  6  or  12 

Ovary  1,  posterior;  cephalic  setae  6;  odontia  12;  vulva  15% (Synodontium  Cobb  1920) 

Ovaries  2;  cephalic  setae  4 ;  odontia  6;  vulva  45-67% 

Tail  clavate;  nema  shorter,  stouter;  amphid  larger Axonolaimus  de  Man  1889 

Tail  conoid;  nema  long,  slender;  amphid  smaller Ascnlaimus  Ditlev.  1919 

(  =  Bathylaimus  Ditlev.  1918) 
External  amphid  spiral,  circular  or  elliptical 
Female  not  known 

Habitat  soil  (possibly  marine);  spinneret  present;  amphid  spiral;  ceph.  set.  0. . .  .(Amphispira  Cobb  1920) 
Habitat  marine 

Amphid  multispire;  wings  0;  annules  very  fine 

Pharyngeal  bulb  none;  lip  region  not  set  off;  head  truncate-conoid;  onch.  3,  small  Alaimonema  Cobb  1920 
Pharyngeal  bulb  present 

Head  cylindroid;  lip  region  discoid,  set  off  by  constriction (Choniolaimus  Ditlev.  1918) 

Head  hemispherical;  lip  region  not  discoid (Amphispira  Cobb  1920) 

Amphid  circular  or  monospire;  spinneret  present 
Nema  cephalated,  striae  ceasing  at  constriction 

Pharynx  none;  head  ±spherical;  amphid  behind  head;  nema  slender,  1.4%. . .  .Cinctonema  Cobb  1920 
Pharynx  definite;  head  ±hemispherical;  amphid  on  head;  nema  wider,  3.8%  (Micromicron  Cobb  1920) 
Nema  not  cephalated 

Annules  strong,  each  of  8  tile-like  elements;  oesphagus  compound Dasynemella  Cobb  1933 

(  =  Dasynema  Cobb  1920) 
Annules  none;  oesophagus  not  compound 

Cephalic  setae  8  or  more;  onchium  minute;  amphid  minute,  at  lips Catanema  Cobb  1920 

Cephalic  setae  4;  onchia  0;  amphid  large,  not  at  lips 

Wing  single;  amphids  on  head,  large,  double,  circular,  joined  dorsally Antomicron  Cobb  1920 

Wings  0;  amphids  behind  head,  not  joined 

Base  pharynx  faintly  cuticularized,  without  ring;  amphid  circular Monhysteriella  Kreis  1929 

Base  pharynx  with  cuticularring,  prongs  2,  vertical;  amphid  monospire.  .Cricolaimux  Southern  1914 
Female  known 

Ovary  1  (for  alternative  see  next  page) 
Gonad  9  outstretched,  anterior ;  amphid  circular;  striae  0,  or  fine  and  plain;  wings  0 

Pharynx  ±quadrate;  neck  under  5%;  crystalline  bodies  lateral;  marine (Crystallonema  Cobb  1920) 

Pharynx  long-conoid;  neck  17%;  spinneret  oresent;  in  fresh  water (Monhystera  Bast.  1865) 

(i.e.  subg.  Monhystrella  Cobb  1918) 
Gonad  9  reflexed ;  cephalic  setae  0  or  minute 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  471 

Spinneret  present;  striae  of  dots;  phar.  denticulate;  post,  ovary  undev.;  marine  Dasylaimus  Cobb  1933 
Spinneret  absent;  pharynx  not  denticulate;  not  marine 
Head  with  6  biting  odontia;  amphid  round;  nema  cephalated  exc. 

Teratocephalus  palustris  ...........................  Teratocephalus  de  Man  1876 

Head  with  entire  or  3-parted  lip  region;  amphid  small,  at  lips;  nema  not 

cephalated,  exc.  Acrobeles  insubricus 
Probolae  absent  ;  cephalic  appendages  0  or  in  1  circlet  .......................  Panagrolaimus  Fuchs  1930 

Probolae  present;  in  soil 
Cephalic  appendages  in  2  circlets  ..............................................  Acrobeles  Linst.  1877 

Cephalic  appendages  in  1  circlet  .............................................  Cephalobus  Bast.  1865 

(  =  Acrobeloides  (Cobb)  Steiner  &  Buhrer  1933) 
Ovaries  2  (for  alternative  see  preceding  page) 
Gonads  9  outstretched 


Amphid  multispire;  striae  fine;  pharynx  small,  cup-shaped 

ale  ventral  pre-anal  supplementary  organs  small  .......................  (Parasabatieria  de  Man  1907) 

Male  supplementary  organs  none  ......................  ."  .................  (Sabatieria  de  Rouville  1903) 


Amphid  circular 

Pharynx  obconoid,  cutic.  rings  1  or  more;  spinneret  pres.;  brackish  soil.  .  .  (Desmolaimus  de  Man  1880) 
Pharynx  without  transverse  cuticularized  rings;  spinneret  present  or  not 
Habitat  not  marine;  cephalic  setae  0 
Spinneret  present;  head  with  4  circular  "warts"  ;  in  fresh  water  .........  Pseudochromadora  Daday  1901 

Spinneret  absent;  head  without  "warts";  bursa  present;  in  moss  ..........  Himatidiophila  Rahm  1925 

Habitat  marine;  striae  fine;  cephalic  setae  present 
The  pharynx  obconoid,  with  cylindroid  vestibule 

Base  pharynx  cuticularized;  head  icylindroid;  cardiac  bulb  valvate.  .   Metalinhomoeus  de  Man  1907 

(cf.  Deltane.ma  Kreis  1929) 

Base  pharynx  not  cuticularized;  head  ±conoid;  lips  if  everted  knob-like  Cryptolaimus  Cobb  1933 
The  pharynx  minute  or  none 

Cardiac  swelling  not  strongly  developed;  ceph.  set.  8-10;  nema  not  tapering  Linhomoeus  Bast.  1865 
Cardiac  bulb  broad,  valvate;  ceph.  set.  4;  nema  tapering,  tail  setaceous  Terschellingia  de  Man  1888 
Gonads  9  reflexed 
Habit   parasitic,   in   insects;  oesophagus  without  median  bulb  .............  Neoaplectana  Steiner  1929 

Habit  free-living 

Spinneret  absent;  cephalic  setae  0;  in  soil  and  fresh  water 

Nema  cephalated,  exc.  T.  palustris;  lip  reg.  lobed,  with  6  biting  odontia.  .  Teralocephalus  de  Man  1876 
Nema  not  cephalated;  lip  region  not  lobate;  bursa  present  ................  Himatidiophila  Rahm  1925 

Spinneret  present 
Cephalic  setae  0;  head  with  4  circular  "warts";  in  fresh  water  ............  Pseudochromadora  Daday  1901 

Cephalic  setae  present;  head  without  "warts" 
Habitat  fresh  water  or  soil;  amphid  circular  to  monospiral  ......................  Plectus  Bast.  1865 

Habitat  marine 
Lips  2,  mouth  a  dorso-ventral  slit;  "pseudonchs"  dorso-  ventral  ridges.  .  .  .  (Pseudonchus  Cobb  1920) 

Lips  more  than  2.  mouth  not  a  slit;  "pseudonchs"  absent 
Amphid  multispire 
Pharynx  irregular,  with  tooth-like  projections  ..............................  Zalonema  Cobb  1920 

Pharynx  simply  conoid,  regular,  without  tooth-like  projections 
Head  set  off  by  absence  of  striae  ..................................  Heterodesmodora  Micql.  1924 

Head  not  set  off;  striae  extending  to  lips;  neck  6-7%;  onchium  minute  .......  Spirina  Fil.  1918 

(  =  Spira  Bast.  1865) 
Amphid  circular  or  monospiral 

The  pharynx  denticulate  ;  post,  ovary  undev.  ;  stria*  of  dots;  wings  pres.  .  .  (Dasylaimus  Cobb  1933) 
The  pharynx  not  denticulate;  both  ovaries  developed 
Dorsal  pharyngeal  wall  not  thickened;  amphid  not  at  lips 

Neck  14-21%;  wings  present;  amphid  long-oval;  head  set  off  by  groove  at  4  cephalic  setae 
Length  of  neck  14-16%;  amphid  large,  £  head-width  back  ..........  Eutelolaimus  de  Man  1922 

Length  of  neck  21%;  amphid  2  head-widths  back  ..........................  Aplectus  Cobb  1914 

Neck  under  7%;  wings  0;  amphid  spiral 

Nema  4-7  mm.;  width  0.3-1%;  phar.  straight,  closed,  with  pharyng.  swelling  Laxus  Cobb  1894 
Nema  2-4  mm.;  width  1.5-4%;  pharynx  conoid,  oft  with  small  onchium  ......  Spirina  Fil.  1918 

(=Spira  Bast.  1865) 

Dorsal  pharyng.  wall  thick,  tooth-like;  amph.  monospire  at  lips;  ceph.  set.  4  ;  renette  far  back 
Oesoph.  glands  obscuring  junct.  of  intest.;  dorsal  phar.  element  dbuniform  Onchium  Cobb  1920 
Oesoph.  glands  not  prominent;  dorsal  pharyng.  element  not  uniformly  thick,  but  heavy 
Tooth-like  thickening  parallel  to  axis  ..............................  Camacolaimus  de  Man  1889 

(  =  Digitonchvs  Cobb  1920 
=  Acontiolaimus  Fil.  1918) 

Tooth-like  thickening  bent  outward  from  beginning  of  vestibule 
Point  of   "onchium"  single  .........................................  Acmaeolaimus  Fil.  1918 

Point  of  Y-shaped  "onchium"  duplex  ....................................  Ypsilon  Cobb  1920 

Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling  (for  alternative  see  preceding  page) 
Amphid  not  known  or  obscure  (for  alternative  see  next  page) 
Female  not  known 
Habitat  marine;  lip  region  discoid;  odontia  6;  ceph.  set.4;  amphid  small  .....  (Stephanolaimus  Ditlev.  1918) 

Habitat  fresh  water,  marsh  or  sand 

Hemispherical  "cap"  wider  than  neck,  edge  setose;  phar.  conoid;  spinneret  pres.  Diplolaimus  Linst.  1876 
Hemispherical  cap  none;  setae  0;  spinneret  0;  wings  double;  bursa  striate.  .  .  .Macroposthonia  de  Man  1880 

Female  known;  spinneret  present 
Ovary  1;  marine 

Gonad  9  reflexed;  ceph.  set.  0,  pharynx  denticulate;  post,  ovary  undev.;  wings  pres.  Dasylaimus  Cobb  1933 
Gonad  9  outstretched  ;  cephalic  setae  4 
The  ovary  anterior;  nema  3  mm.;  neck  12%,;  vulva  75%  ........................  Krampia  Ditlev.  1922 

The  ovary  posterior;  nema  1  mm.  ;  neck  19%;  vulva  35%  .......................  Asymmetrica  Kreis  1929 

Ovaries  2,  reflexed 

Habitat  fresh  water  (for  alternative  see  next  page) 
Lips  3,  rounded;  pharynx  small,  closed;  onchium  minute,  deepset  ..................  (Tripyla  Bast.  1865) 

(  =  Promononchus  Micol.  1923) 


472  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Lips  6,  thin;  pharynx  larger,  domed;  onchia  in  posterior  chamber (Trilobus  Bast.  1866) 

Habitat  marine  (for  alternative  see  preceding  page) 

Wings  conspic. ;  striae  of  dots ;  ceph .  set.  0  ;pharynx  denticulate ;  post  .ovary  undev . .  Dasylaimus  Cobb  1933 
Wings  0,  striae  plain,  not  altered  laterally;  cephalic  setae  present;  Enoplidae 

Calvarium  elaborate,  ornate;  onchia  often  present Deontostoma  Fil.  1916 

Calvarium  not  elaborate,  sometimes  absent 
Oesophagus  crenate  towards  base;  calvarium  simple  or  reduced 

Eyes  0;  neck  rttapering;  calvarium  reduced;  cervical  setae  in  several  rows Stenolaimus  Marion  1870 

Eyes  with  lenses 

Pharynx  simple ;  calvarium  reduced ;  neck  tapering Nasinema  Fil.  1927 

Pharynx  with  tooth-like  processes;  calvarium  simple;  neck  icylindroid Phanoderma  Bast.  1865 

(  =  Heterocephalus  Marion  1870) 
Oesophagus  not  crenate;  calvarium  absent 

Jaws  3,  without  mandibles  or  onchia (Parenoplus  Fil.  1927) 

Jaws  absent 

The  pharynx  tapering  into  oesophagus;  cephalic  setae  6,  cervical  small.  .Paroxy stamina  Micol.  1924 
The  pharynx  broad.thin-walled.base  truncate  with  mound  ;amph. with  pocket  Pelagonema  Cobb  1894 

(cf.  Vasculonema  Kreis  1928) 

Amphid  known  (for  alternative  see  preceding  page) 
External  amphid  not  spiral,  circular  nor  elliptical ;  female  known 
Ovary  1 ;  amphid  not  linear 

Gonad  9  outstretched;  lips  6,  thin,  each  with  3  parallel-sided  cutic.  ribs;  marine  Daptonema  Cobb  1920 

(cf.  Theristus  Bast.  1865) 
Gonad  9  reflexed 

The  ovary  posterior;  spinneret  absent;  marine (Rhabdocoma  Cobb  1920) 

The  ovary  anterior,  vulva  80%;  spinneret  present;  soil  about  sugar  cane Trischistoma  Cobb  1913 

Ovaries  2 
Gonads  9  outstretched;  marine  exc.  Monhystera 

Habitat  soil  among  roots;  amphid  a  transverse  slit;  pharynx  ovoid Monhj/stera  Bast.  1865 

(  =  M.  dintheriana  de  Man  1885) 
Habitat  marine 

Amphid  large,  long-oval,  on  triangular  plate,  ±as  wide  as  head;  spinneret  none. . .  .Didelta  Cobb  1920 
Amphid  not  on  special  plate 

Mouth  ventrad  of  axis;  amphid  large,  long,  "folded1 Campylaimws  Cobb  1920 

Mouth  axial;  amphid  shorter 

Odontia  absent;  amphid  flattened,  more  or  less  reniform Margonema  Cobb  1920 

Odontia,  if  present,  6  or  12;  amphid  crook-shaped  or  "folded" 

Tail  clavate;  body  less  slender;  amphid  larger Axonolaimus  de  Man  1889 

Tail  conoid;  body  slender;  amphid  smaller Ascolaimus  Ditlev.  1919 

(  =  Bathylaimus  Ditlev.  1918) 
Gonads  9  reflexed 
Habitat  freshwater 

Pharynx  larger,  domed;  lips  6,  thin;  onchia  small,  in  posterior  pharynx (Trilobus  Bast.  1865) 

Pharynx  small,  closed;  lips  3,  rounded;  onchium  minute,  deepset (Tripyla  Bast.  1865) 

(  =  Promononchus  Micol.  1923) 
Habitat  marine 

Wings  present;  amphid  a  transverse  slit  almost  as  wide  as  head Actinonema  Cobb  1920 

Wings  absent;  amphid  with  internal  pocket  (Rhabdocoma  ?);  Enoplidae  (Rhabdocoma  ?) 
Oesophagus  crenate  towards  base 

Pharynx  without  tooth-like  processes;  cervical  setae  in  longitudinal  rows. .  .Stenolaimus  Marion  1870 
Pharynx  with  2-3  forward-pointing  tooth-like  processes;  calvarium  pres..  .(Phanoderma  Bast.  1865) 

(  =  Heterocephahis  Marion  1870) 
Oesophagus  not  crenate 
Calvarium  present;  onchia  often  1-3 

The  calvarium  elaborate,  ornate,  relatively  short Deontostoma  Fil.  1916 

The  calvarium  a  mere  band, margin  wavy  ;external  amphid  transverse-oval  Cylicolaimus  de  Man  1889 
Calvarium  absent 

Lateral  series  of  setae  on  neck  absent;  spinneret  absent (Rhabdocoma  Cobb  1920) 

Lateral  series  of  setae  on  neck  of  few  members 

Excretory  pore  on  projection;  pharynx  definite,  iquadrate;  testis  1. ..  .Paranticoma  Micol.  1930 
Excretory  pore  not  raised;  pharynx  ±conoid,  often  obscure;  testes  2 

Gubernaculum  present;  cf  pre-anal  ventral  supplementary  organ  tubular  Anticoma  Bast.  1865 
Gubernaculum  none;  cf  ventral  pre-anal  supplementary  organ  papilloid  Anticomopsis  Micol.  1930 
External  amphid  spiral,  circular  or  elliptical 

Female  not  known;  marine  exc.  Dintheria  (for  alternative  see  next  page) 

Spinneret  none;ceph.set.4,long;amph.transverse-oval,|  head- width, open  caudad  Dintheria  de  Man  1921 
Spinneret  present  (Neurella,  Bognenia  ?) 

Nema  broad,  tapering  from  head  to  tail;  wings  12-24;  amphid  spiral Pteronium  Cobb  1933 

Nema  slender,  not  widest  at  head;  wings  none  or  few 
Amphid  multispire 

Wing  single;  cephalic  setae  4;  amphid  broad,  of  few  winds;  spinneret(?) Neurella  Cobb  1920 

Wings  absent;  striae  not  altered  laterally 

Onchia  3,at  tops  apophyses;ceph.set.papilloid;pharynx  complex.bulb  strong  Trogolaimus  Cobb  1920 
Onchia  0;  cephalic  setae  longer;  lips  flap-like,  at  least  distally 

Lip  supports  thickened;  phar.  cyathiform;  cf  supplements  many,  chromadoroid  Dispira  Cobb  1933 
Lip  supports  none;  pharynx  spheroid,  on  front  of  head;  cf  supplements  0.  .Dispirella  Cobb  1933 
Amphid  circular,  elliptical  or  monospiral 
Wings  strong;  amphid  circular  or  monospiral 

Oesoph.compound.wide  anteriorly .card.bulb  faint ;amph. spiral jannules  wide  Daaynemella  Cobb  1933 

(  =  Dasynema  Cobb  1920) 
Oesoph.  not  compound;  amphid  circular 

The  wings.12,  of  spine-like  markings Xenolaimus  Cobb  1920 

The  wing  single,  with  subordinate  lines;  amphids  joined  dorsally (Antomicron  Cobb  1920) 

Wings  0;  striae  not  altered  laterally 

Onchium  ±spear-like;  cephalic  setae  10;  cephalic  cuticle  thickened;  eyes  2  (Cophonchus  Cobb  1920) 
Onchium  none  (Nudolaimus  ?) 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  473 

Nema  9-10  mm.;  striae  0;  pharyngeat  walls  heavily  cuticularized;  amphid  small 
Amphid  labial,  spiral;  phar.  large,  processes  basal;  ceph.  set.  4;  eyes  0  . .  (Niidolaimiw  Allgen  1929) 
Amphid  1  head-width  back,  oval;  phar.  small;  ceph.  set.   10;  eyes  2      Leptoxomatides  Fil   1918 
Nema  under  3  mm.;  cephalic  setae  4-6 
Cephalic  setae  at  least  2  head-widths  long 

Lip  region  discoid,  set  off;  odontia  6;  amphid  small,  oval Stephanolaimus  Ditlev.  1918 

Lip  region  not  discoid;  odontia  none;  amphid  large,  circular Cenolaimus  Cobb  1933 

Cephalic  setae  not  over  1  head- width  long;  lip  region  not  discoid;  odontia  0 

Pharynx  a  wide  tube;  head  strongly  conoid;  width  of  nema  6% Tubolaimus  Allgen  1929 

Pharynx  shallow;  head  not  strongly  conoid 

Cutjcle  annulated;  amphid  oval,  near  lips;  lips  3,  massive,  low Zygonemella  Cobb  1920 

Cuticle  with  fine  striae  or  none;  amph.  circular,  ±1  head-width  back;  lips  ±confluent 

Ribs  of  pharynx  6,  cuticularized,  parallel  to  axis Rhadinema  Cobb  1920 

Ribs  of  pharynx  none;  pharynx  conoid Bognenia  Allgen  1932 

Female  known  (for  alternative  see  preceding  page) 
Ovary  1;  amphid  not  multispire 
Gonad  9  reflexed;  amphid  circular  or  elliptical 
The  ovary  posterior;  marine 

Spinneret  none;  cephalic  setae  4;  tail  usually  about  40% Rhabdocoma  Cobb  1920 

Spinneret  present;  cephalic  setae  0;  tail  about  3% Nemanema  Cobb  1920 

The  ovary  anterior;  cephalic  setae  present  (in  Monhystrium  sometimes  papilloid) 
Habitat  not  marine;  spinneret  present 
Pharynx  deep;  onch.  small,  basal;  lips  massive,  with  flaps;  vulva  80%;  soil  (Trischistoma  Cobb  1913) 

Pharynx  less  deep,  vestibule  definite;  onchia  0;  in  gills  of  land  crabs (Monhystrium  Cobb  1920) 

Habitat  marine 

Spinneret  0;  ceph.  set.  10;  caudal  setae  thorn-like;  amphid  large,  center  raised  (Zanema  Cobb  1920) 
Spinneret  pres.;  ceph.  set.  4,  small;  thorn-like  setae  0;  phar.  ±cylind.  .(Conolaimella  Allgen  1930) 


CSonad  9  outstretched,  anterior;  usually  marine 
Spinneret  none;  wings  0;  amphid  circular;  marine 
Amphid  large,  with  central  mound;  caudal  setae  thorn-like;  nema  0.9%  wide.  .(Zanema  Cobb  1920) 


Amphid  not  raised  centrally;  caudal  setae  if  present  not  thorn-like 

Labial  palps  6;  pharynx  iquadrate;  tail  conoid,  4% Crystallonema  Cobb  1920 

Labial  palps  0;   pharynx  conoid  then  spheroid;  tail  long,   filiform. .. .(Diplolaimella  Allgen  1929) 
Spinneret  present;  marine  exc.  Monhystrium,  and  sometimes  Monhystera  and  Theristus 
Lips  3,  each  with  finger-like  odontium;  striae  coarse;  wings  32,  fewer  towards  tail  Xyala  Cobb  1920 
Lips  without  finger-like  processes;  wings  0  or  few 

Mouth  cavity  large,  complex,  of  several  chambers,  the  first  of  radial  elements;  carnivorous 
Base  pharynx  unsymmetrical, meeting  oesoph.  ;middle  chamber  denticulate  Sphaerolaimus  Bast.  1865 
Base  pharynx  symmetrical.oesoph. surrounding  2  chambers ;dents.O  Parasphaerolaimus  Ditlev.  1918 
Mouth  cavity  smaller,  of  1  or  2  chambers,  walls  relatively  simple 

Lips  6,  conoid,  twice  high  as  broad,  with  hook-shaped  set. ;  amph.  monospire  Dactylaimus  Cobb  1920 
Lips  not  as  high  as  broad,  without  hook-shaped  setae;  mostly  Monhysterinae 
Caudal  glands  pre-anal,  reaching  vulva;  excret.  pore  nr.  phar.;  ceph.  set.  4  Conolaimella  Allgen  1930 
Caudal  glands  post-anal;  excret.  pore  nr.  nerve  ring,  when  seen;  ceph.  set.  oft  many 

Labial  ribs  18,  cuticularized,  parallel-sided;  testes  2 Daptonema  Cobb  1920 

(cf.  Theristus  Bast.  1865) 

Labial  ribs  absent  or  (Monhystrium)  reduced  ;genera  resembling  Monhystera.exc.Sphaerocephalum 
Margin  of  transverse-oval  amphidial  area  not  definite,  sensory  papilla  at  posterior  margin 

Intestine  narrow,  J  body-width;  gubernaculum  tubular Leptogastrella  Cobb  1920 

Intestine  wider(?);  gubernaculum  not  tubular(?) Paramonhystera  (Steiner)  Fil.  1918 

Margin  of  amphidial  area  definite,  sensory  papilla  not  obvious 

Habitat  gills  of  land  crabs;  cephalic  setae  10,  sometimes  papilloid Monhystrium  Cobb  1920 

Habitat  aquatic;  marine  exc.  sometimes  Monhystera  and  Theristus 

Pharynx  conoid,  then  spheroid;  striae  fine  or  0;  eyes  oft  present.  .Diplolaimella  Allgen  1929 
Pharynx  without  spheroid  chamber;  amphid  circular  exc.  Sphaerocephalum 
Amphid  monospire;  neck  5-9%;  spinneret  wide,  plug  striated. .  .Sphaerocephalum  Fil.  1918 
Amphid  circular;  neck  10-27%;  spinneret  without  striated  plug 

Oesophagus  wide  in  post,  half ;  spicula  hamate  distally;  gubernaculum  0  Austronema  Cobb  1914 
Oesophagus  not  wider  posteriorly;  gubernaculum  present 

Setae  on  head  8-fold;  somatic  set.  oft  long.  .Steineria  (Micol.)  Stekhoven  &  de  Coninck  1933 
Setae  on  head  not  8-fold;  long  paired  somatic  setae  absent 

Gubernaculum  tubular,  barbed,  apophysis  none Fernanda  (de  Man)  Fil.  1918 

Gubernaculum  not  tubular 

Spicula  not  much  bent;  gubernac.  apophysate;  mostly  freshwater. .  .Monhystera  Bast.  1865 

(  =  Tachyhodites  Bast.  1865) 

Spicula  much  bent  or  sickle-shape;  gubernac.  plate-like,  dorsad Theristus  Bast.  1865 

(  =  Allomonhystera  Micol.  1923) 
(cf.  Daptonema  Cobb  1920) 
Ovaries  2 

Gonads  9  outstretched;  marine  (for  alternative  see  next  page) 
Nema  12-16%  wide;  neck  "collared";  amphid  spiral;  wings  many;  spinneret  present 

Wings  over  50;  pharynx  narrow;  spicula  2,  equal... Richtersia  Steiner  1916 

Wings  16-20,  in  pairs;  pharynx  capacious,  open;  spicula  unequal,  or  but  1 . .     (Kichtersiella  Kreis  1929) 
Nema  under  3%  wide;  neck  not  "collared";  wings  if  present  not  numerous 
Spinneret  absent;  amphid  circular  exc.  Didelta 

Setae  none;  amphid  ihalf  as  wide  as  head Metalaimus  Kreis  1928 

Setae  present;  amphid  small  exc.  Didelta 

Amphid  very  large,  long-oval,  on  triangular  plate;  cephalic  setae  4 Didelta  Cobb  1920 

Amphid  small,  not  on  plate;  cephalic  setae  6  or  more 

Pharyngeal  bulb  distinct;  cephalic  setae  6,  stout,  jointed Cytolaimium  Cobb  1920 

Pharyngeal  bulb  none;  setae  on  head  18,  small;  amph.  with  faint  multispire. .  Anticyathux  Cobb  1920 
Spinneret  present;  cephalic  setae  present  exc.  Margonema 
External  amphid  multispire 

Male  ventral  pre-anal  supplementary  organs  papilloid Parasabatieria  de  Man  1907 

Male  supplementary  organs  none Sabatieria  de  Rouville  1903 

External  amphid  not  multispire  (Linhomoella  faintly  so) 


474  PROCEEDINGS   HELMINTHOLOGK'AL   SOCIETY  VOL.  2,  NO.  1 

Amphid  wider  than  long,  ±reniform;  lips  3,  double,  with  papillae Margonema  Cobb  1920 

Amphid  circular  or  monospiral 

Lips  distinct,  with  distal  flaps;  ceph.  set.  6,  stout,  jointed;  papillae  6. . .  .Cytolaimium  Cobb  1920 
Lips  absent  or  confluent 

Oesoph.  &lumen  with  oval  enlargement  behind  eyes  ;eyes  sometimes  none  Araeolaimux  de  Man  1888 
Oesoph.  without  median  enlargement;  eyes  0;  cephalic  setae  6-10 
Setae  on  head  10,  shorter  4  specialized  at  tip;  amph.  faint  multispire. .  (Linhomoella  Cobb  1920) 

Setae  on  head  6-8,  without  specialized  tips;  amphid  circular Linhomoeus  Bast.  1865 

Gonads  9  reflexed  (for  alternative  see  preceding  page) 
Habitat  not  marine  exc.  sometimes  Aphanolaimus 

Spinneretabsent;  amphid  multispire;  setae  0;  striae  of  dots;  in  sand  dunes.  .Choanolaimus  de  Man  1880 
Spinneret  present 

Wings  present;  contour  crenate;  glands  lateral,  serial ;  amphid  monospire. .  Aphanolaimus  de  Man  1880 
Wings  0,  striae  not  altered  laterally;  contour  not  erenate;  amphid  circular  or  oval 
Lips,  papillae  &  setae  0;  amphid  round;  pharynx  small,  conoid,  unarmed  Diplohystera  de  Cillis  1917 
Lips,  papillae  &  small  setae  pres.;  amph   small,  oval;  phar.  closed;  onch.  basal  Tripyla  Bast.  1865 

(  =  Promononchus  Micol.  1923) 
Habitat  marine 

Amphid  spiral ;  spinneret  present 

Pharynx  with  apophyses  forward  and  backward  from  mid-region 
Mid-pharyngeal  region  not  denticulate;  wings  numerous,  markings  V-shaped. . .  .Nunema  Cobb  1933 

Mid-pharyngeal  region  denticulate Halichoanolaimus  de  Man  1886 

(  =  Smalsundia  Allgen  1929) 

Pharynx  without  forward  apophyses;  mid-pharyngeal  region  not  denticulate 
Wings  numerous;  neck  region  "collared";  nema  12-16%  wide 

Spicula  2;  wings  over  50;  pharynx  narrow Richtersia  Steiner  1916 

Spicula  unequal,  or  1  only;  wings  16-32;  pharynx  capacious,  open (Richtersiella  Kreis  1929) 

Wings  absent,  striae  if  present  not  altered  laterally 

Jaws  3,  with  backward  apophyses  and  numerous  horny  teeth  anteriorly Demonema  Cobb  1894 

Jaws  absent,  pharynx  without  apophvses 

Pharynx  2  chambers;  ceph.  set.  10.  oft  jointed,  tips  specialized;  striae  fine  Tripyloides  de  Man  1886 
Pharynx  1  chamber;  tips  setae  unspecialized;  striae  less  fine;  eyes  present 

Cuticular  pores  none;  pharynx  with  definite  bulb Nannolaimus  Cobb  1920 

Cuticular  pores  present;  pharvnx  without  definite  bulb Cyatholaimus  Bast.  1865 

(  =  Necticonema  Marion  1870) 
Amphid  circular,  elliptical  or  monospiral 

Spinneret  absent;  cephalic  setae  4.  stout;  tail  usually  ±40% Rhabdocoma  Cobb  1920 

Spinneret  present 

Oesophagus  crenate  towards  base;  calvarium  reduced 
Cervical  setae  in  long,  rows;  pharynx  ±none;  ext.  amph.  ±semi-circular  (Stenalaimus  Marion  1870) 

Cervical  setae  0 Phanodermopsis  Ditlev.  1926 

(  =  Galeonema  Fil.  1927) 
Oesophagus  not  crenate 
Calvarium  present;  onchia  often  1-3 

The  calvarium  elaborate,  ornate Deontostoma  Fil.  1916 

The  calvarium  a  wavy  band;  often  denticles  at  lips;  amphid  transverse.  .Cylicolaimus  de  Man  1889 
Calvarium  absent 

Jaws  3,  with  simple  supporting  framework Parenoplus  Fil.  1927 

Jaws  absent 
Pharynx  of  2  chambers 

Chambers  of  pharynx  ±equal.  small;  cephalic  setae  0 Pseudopelagonema  Kreis  1932 

Chambers  of  pharynx  unequal,  anterior  large;  setae  10.  often  jointed,  tips  specialized 

Both  chambers  ±conoid  or  irregular  in  shape Tripyloides  de  Man  1886 

Both  chambers  ±parallel-sided Bathylaimus  Cobb  1894 

(  =  Macrolaimus  Ditlev.  1918 
=  Cothonolaimus  Ditlev.  1919) 

Pharynx  of  1  chamber;  setae  without  specialized  tips 

Dorsal  pharyng.  wall  thick,  tooth-like;  amph.  monospire  at  lips;  ceph.  set.  4;  renette  far  back 
Oesoph.  glands  obscuring  junct.  of  intest.;  dorsal  phar.  element  ±uniform  Onchium  Cobb  1920 
Oesoph.  glands  not  prominent;  dorsal  pharyng.  element  not  uniformly  thick,  but  heavy 

Tooth-like  thickening  parallel  to  axis Camacolaimus  de  Man  1889 

(  =  Digitonchus  Cobb  1920 
=  Acontiolaimus  Fil.  1918) 
Tooth-like  thickening  bent  outward  from  beginning  of  vestibule 

Point  of  "onchium"  single Acmaeolaimus  Fil.  1918 

Point  of  Y-shaped  "onchium"  duplex Ypsilon  Cobb  1920 

Dorsal  pharyngeal  wall  not  thickened;  amphid  not  at  lips;  Enoplidae,  exc.  Aphanolaimus 
The  pharynx  open,  capacious,  walls  usually  heavily  cuticularized;  amphid  with  pocket 

External  amphid  circular;  wall  of  pharynx  irregularly  thick (Pandolaimus  Allgen  1929) 

External  amphid  small, transverse;pharyng.  wall  thin. base  with  mounds  Pelagonerna  Cobb  1894 

(cf.  Vasculonema  Kreis  1928) 
The  pharynx  small  or  very  narrow 

Cervical  setae  absent;  cephalic  setae  4,  in  front  of  amphid Aphanolaimus  de  Man  1880 

Cervical  setae  lateral,  in  short  longitudinal  series;  amphid  with  pocket 

Gubernaculum  present;  cf  supplementary  organ  tubular Anticoma  Bast.  1865 

Gubernaculum  none;  cf  supplementary  organ  papilloid Anticomopsis  Micol.  1930 

Carity  more  or  less  cylindroid  or  prismoid,  i.e.  parallel-sided  in  long,  section  (for  alt.  see  page  470) 
Oesophagus  with  median  or  posterior  bulb  or  swelling,  or  both  (for  alternative  see  page  477) 
Amphid  not  known  or  obscure  (for  alternative  see  next  page) 
Female  not  known 

Spinneret  none;ceph.set.0;phar.closed;oesoph.cephaloboid;neck  over  20%;in  swamp  Litonema  Cobb  1920 
Spinneret  present;  setae  on  head  numerous;  neck  under  5%;  amphid  small,  near  lips;  marine 

Pharyngeal  bulb  present;  striae  none;  length  3-4  mm. ;  onchia(?)  6,  minute (Catanema  Cobb  1920) 

Pharyngeal  bulb  none;  striae  annulating  the  cuticle;  length  10  mm (Laxonema  Cobb  1920) 

Female  known;  spinneret  none  exc.  Rhabdolaimus;  not  marine;  phasmids  usually  present 


Spi 
C 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  475 

Ovary  1,  anterior;  cephalic  setae  0  or  minute 
Gonad  9  outstretched 

Pharynx  long,  tubular,  base  halfway  to  nerve  ring:  spear  none;  median  bulb  0  .  .  Gymnolaimus  Cobb  1913 
Pharynx  base  ±J  distance  to  nerve  ring;  spear  reduced;  oes.  bulb  strong  (Aphelenchoides  Fischer  1894) 

(  =  Seinura  Fuchs  1931 
=Parasitaphelenchus  Fuchs  1930 

Gonad  9  renewed  -Pathoaphelenchus  (Cobb)  Steiner  1931) 

Median  oesophageal  bulb  present 

Pharynx  wide  as  long;  cardiac  bulb  not  valvate,  median  valvate;  bursa  none.  .Lycolaimus  Rahm  1928 
Pharynx  much  longer  than  wide;  cardiac  bulb  valvate;  bursa  present  .............  Rhabditis  Duj.  1845 

(  =  Diploscapteroides  Rahm  1928 
=Pseudorhabditis  Kreis  1929) 

Median  oesophageal  bulb  absent;  in  soil  and  fresh  water 
Cardiac  swelling  long,  non-valvate;  pharyng.  rods  heavily  cuticular  ____  Diphtherophora  de  Man  1880 

(  =  Chaolaimus  Cobb  1893 
=  Archionchus  Cobb  1913) 

Cardiac  bulb  valvate,  preceded  by  isthmus,  i.e.  oesoph.  cephaloboid;  pharyng.  rods  none 
Head  end  lobed  by  6  large  biting  lips  or  odontia;  carnivorous  ...........  (Teratocephalus  de  Man  1876) 

Head  end  not  lobed,  exc.  in  Acrobeles  insubricus 

Pharynx  wall  simple.forming  2  chambers  ;onchium  oft  present;ceph.set.O-4  Macrelaimus  Maupas  1900 
Pharynx  wall  of  a  longitudinal  series  of  elements,  i.e.  cephaloboid 
Probolae  on  head  none  ...................................................  Panagrolaimus  Fuchs  1930 

Probolae  on  head  in  1  or  2  circlets 
Circlets  of  probolae  2,  elements  often  elaborate  ................................  Acrobeles  Linst.  1877 

Circlet  of  probolae  single  .....................................................  Cephalobus  Bast.  1865 

(  =  Acrobelmdes  (Cobb)  Steiner  &  Buhrer  1933) 
Ovaries  2;  cephalic  setae  0,  exc.  in  Teratocephalus  minute 

Gonads  9  outstretched;  ceph.  set.  0;  phar.  tubular,  reaching  oesoph.  bulb;  in  soil  Aulolaimus  de  Man  1880 
Gonads  9  reflexed 
Spinneret  present;  wings  absent;  in  fresh  water  and  moist  soil  ...............  Rhabdolaimus  de  Man  1880 

inneret  absent 

uticle  with  prominent  tubercles;  lip  reg.  set  off  by  constrict.;  ceph.  set.  with  saccate  bases 
Tubercles  encrusting  dorsal  surface;  wings  broad,  thin;  in  moss  ..........  Craspedonema  Richters  1908 

Tubercles  in  longitudinal  row(s),  right  lateral;  oesophagus  rhabditoid  .....  Bunonema  Jagerskiold  1905 

(  =  Rhodolaimus  Fuchs  1930) 
Cuticle  without  tubercles 

Pharynx  a  long  straight  tube,  \  neck  length  or  more 

Oesoph.  short,  a  muscular  bulb  only;  <?  supplements  few,  ventral,  pre-anal  Aulolaimus  de  Man  1880 
Oesoph.  long,  of  2  parts;  cf  supplements  paired,  post-anal,  i.e.  diplogastroid 
Male  papillae  9  pairs;  gubernaculum  sigmoid;  labial  papillae  16  .............  Myctolaimus  Cobb  1920 

Male  papillae  10  pairs  ;  gubernaculum  straight  ;  bursal  membrane  narrow  .  .  Cylindrogaster  Goodey  1927 
Pharynx  not  a  simple  tube,  much  shorter 
Oesophagus  without  median  bulb 

Cuticularized  rods  supporting  pharynx;  shed  cuticle  surrounding  nema  Diphtherophora  de  Man  1880 

(  =  Chaolaimus  Cobb  1893 
=  Archionchus  Cobb  1913) 
Cuticularized  pharyngeal  rods  none 
Head  end  lobed  by  6  large  biting  lips  or  odontia;  carnivorous  ........  (Teratocephalus  de  Man  1876) 

Headend  n&t  lobed;  bursa  present  .............................................  Rhabditis  Duj.  1845 

Oesophagus  with  median  and  cardiac  bulbs 

Cardiac  bulb  valvate;  median  bulb  well  set  off;  glottoid  apparatus  present 
Wall  of  pharynx  cylindroid;  bursa  present;  cf  tail  rhabditoid  ..................  Rhabditis  Duj.  1845 

Wall  of  pharynx  convex  inward;  bursa  much  reduced;  cf  tail  long,  spicate  Rhabditoides  Goodey  1929 

(=Rhabditella  (Cobb)  Chitwood  1933) 

Cardiac  bulb  without  valve;  median  bulb  valvate;  d"  tail  setaceous,  diplogastroid 
Pharyng.  rods  3,  basal  bulbs  2,  stalked;  tail  25-41%;  long,  striae  fine  ......  Tylopharynx  de  Man  1876 

Pharyng.  bulbed  supporting-rods  none;  Diplogasterinae 
Nema  with  evident  longitudinal  striation  ...........................  Diplogaster  M.  Schultze  1857 

Nema  without  longitudinal  striation 
Pharynx  wide  as  deep,  wa}l  of  several  elements;  d"  papillae  0(?)  .......  Peronilaimus  Rahm  1928 

Pharynx  tubular,  wall  entire;  d1  papillae  usually  5  pairs  ...............  Rhabditidoides  Rahm  1928 

Amphid  known  (for  alternative  see  preceding  page) 

External  amphid  not  spiral,  circular  nor  elliptical  (for  alternative  see  next  page) 
Habitat  marine;  cephalic  setae  and  spinneret  present;  amphid  crook-shaped,  sometimes  =tspiral 
Ambulatory  &  somatic  set.  0;  nema  not  crooked,  not  narrowed  in  card.  reg.  ;  ventral  arm  amph.  pr 
Phar.  wide.heavy,  4-5%  ;amphid  long,4-50%  body  ;ceph.  setae  4,subceph.l2;  -9-.  -  .Pseudolella  Cobb 
Phar.  narrow,inconspic.;amph.  under  2%;ceph.set.6,subceph.4;annules  tiled;  '9'  Ceramonema  Cobb  1920 

(cf.  Pselionema  Cobb  1933) 

Ambulatory  set.  forming  ventral  pre-anal  sole;  nema  ±S-shape,  narrowed  in  card,  reg.;  marine;  '9' 
Oesoph.  region  hardly  swollen;  card,  bulb  faint;  cerv.  striae  all  alike.  .  Notochaetosoma  Irwin-Smith  1918 
Oesoph.  region  swollen,  ovoid;  oesophageal  bulbs  1  or  2;  band  of  cervical  striae 
accentuated,  exc.  Tristicochaeta  falcatum 
Ventral  ambulatory  adhesion  tubes  or  setae  in  2  rows  .........................  Drepanonema  Cobb  1933 

(  =  Chaetosoma  Clap.  1863) 
Ventral  ambulatory  adhesion  tubes  or  setae  in  3  or  4  rows  ..................  Tristicochaeta  Panceri  1878 

(  =  Draconema  Cobb  1913) 
Habitat  not  marine 

Spinneret  present;  '  9  ',  exc.  Chronogaster 

Li  ps  6,  distinct,  revplute;  pharynx  9%;  amphid  semicircular;  soil  about  cane  roots  Anthonema  Cobb  1906 
Lips  not  revolute;  in  fresh  water 
Cephalic  setae  4;  pharynx  wider,  under  1.5%;  '9  ...............................  Chronogaster  Cobb  1913 

Cephalic  setae  0;  pharynx  long-tubular;  tail  25-30%  .........................  Rhabdolaimus  de  Man  1880 

Spinneret  absent;  cephalic  setae  0  or  papilloid 

Tail  setaceous,  19%;oesoph.  with2  bulbs;  amph.  semicircular;  vulva  21%;  '9'  Aulolaimnidex  Micol.  1915 
Tail  not  setaceous,  under  15%;  oesophagus  without  median  bulb,  exc.  Cheilobu? 


476  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Amphid  transverse,  curved,  wide  as  head;  phar.  7.6%;  tail  2%;  fresh  water;  cf  only  Colpurella  Cobb  1920 
Amphid  inconspicuous,  small  or  slit-like;  tail  over  9%;  in  soil  or  decaying  material 
Median  oesoph.  swelling  before  isthmus;  cardiac  bulb  valvate;  wings  single; '  9  '.  .Cheilobus  Cobb  1924 

(  =  Rhabditophanes  Fuchs  1930) 
Median  oesoph.  bulb  absent 

Pharynx  closed;  amphid  a  pore,  with  internal  cuticularized  tube;  wings  2;  J Litonema  Cobb  1920 

Pharynx  open,  or  with  anterior  open  chamber;  wings  0;  cf1  only 

Tail  15%,  terminus  setaceous;  pharynx  without  cuticularized  rods (Monhystera  Bast.  1865) 

(  =  M.  dintheriana  de  Man  1885) 

Tail  8%,  conoid;  cuticularized  rods  in  pharynx;  shed  cuticle  retained. . . Diphtherophora  de  Man  1880 

(  =  Chaolaimus  Cobb  1893 
=  Archionchvs  Cobb  1913) 

External  ampbid  spiral,  circular  or  elliptical  (for  alternative  see  preceding  page) 
Female  not  known;  spinneret  present 

Habitat  soil;  ceph.  set.  0;  ceph.  cuticle  thick,  flaps  doming  vestibule;  amph.  spiral  Pycnolaimus  Cobb  1920 
Habitat  marine;  cephalic  setae  present 
Amphid  multispire;  annules  not  coarse;  wings  absent 

Head  cylindroid;  lip  reg.  set  off  by  constriction;  pharyng.  bulb  present.  .(Choniolaimus  Ditlev.  1918) 
Head  truncate-conoid ;lip  reg. not  set  off  ;pharyngeal  bulb  none;onch.3, minute  Alaimonema  Cobb  1920 
Amphid  circular,  elliptical  or  monospiral 

Wings  8;  annules  coarse;  oesoph.  to  isthmus  wide,  muscular;  card,  swelling  slight  Dasynemella  Cobb  1933 

(  =  Dasynema  Cobb  1920) 
Wings  0 

Cutilarized  pharyng.  ring  basal;  ceph.  set.  4;  <?  supplements  tubular,  14 Cricolaimus  Southern  1914 

Cuticularized  pharyngeal  ring  none 

Spiculum  1,  gubernaculum  absent;  cephalic  setae  10;  amphid  large,  oval.  .Pelagonemella  Kreis  1932 
Spicula  2,  gubernaculum  present  (Chloronemella?);  cephalic  setae  in  circlets  of  4 

Striae  coarse;  amphid  minute;  length  10  mm. ;  width  0.8% Laxonema  Cobb  1920 

Striae  fine;  length  under  4  mm. 

Pharyngeal  bulb  present;  amphid  at  lips;  onchia  6,  minute Catanema  Cobb  1920 

Pharyngeal  bulb  none;  amphid  behind  pharynx;  onchia  0 Chloronemella  Allgen  1929 

Female  known 
Ovary  1 
Gonad  9  outstretched,  anterior;  amphid  circular;  wings  absent 

Spinneret  present;  pharynx  long-conoid;  neck  17%;  in  fresh  water Monhystera  Bast.  1865 

(i.e.  subg.  Monhystrella  Cobb  1918) 
Spinneret  absent;  neck  not  over  5%;  marine 

Pharynx  wide  as  deep;  cardiac  swelling  faint,  elongate;  intestine  not  dark . . Crystallonema  Cobb  1920 
Pharynx  tubular;  posterior  }-J  oesoph.  a  massive  bulb;  intestine  dark  colored  (Solenolaimus  ?) 
Cephalic  setae  minute;  neck  1.4%;  anterior  oesoph.  fusiform;  tail  rounded. .Solenolaimus  Cobb  1894 
Cephalic  setae  often  as  long  as  mitreform  head  is  wide;  neck  2-5% 

Anterior  oesoph.  not  fusiform;  pharynx  not  eyertible;  cf  supplements  0  —  Chromagaster  Cobb  1894 
Anterior  oesoph. fusiform;phar. "spear"  evertible;  cf  supplements pres..Siphonolaimus  de  Man  1893 
Gonad  9  reflexed;  wings  often  present;  not  marine  exc.  rarely  Rhabditis 

The  ovary  posterior, vulva  21%;med.bulb  not  valvate;amph.semicirc.;mud..  Aulolaimoides  Micol.  1915 
The  ovary  anterior 

Spinneret  pres.;  ceph.  set.  4;  card,  bulb  0  or  faint;  amph.  monospire;  fresh  water  (Anonchus  Cobb  1913) 
Spinneret  none;  setae  none,  cephalic  papillae  sometimes  setose 
Oesophageal  bulbs  median  and  cardiac;  pharynx  simple;  setae  0 

Cardiac  bulb  valvate;  amphid  at  lips,  obscure;  wings  &  bursa  pres.;  ubiquitous  Rhabditis  Duj.  1845 
Cardiac  bulb  not  valvate,  median  valvate;  amph.  transverse-oval,  not  at  lips;  phar.  cylindroid 

Dorsal  onchium  none;  bursa  present;  ectoparasitic  on  beetle  borer Rhabditolaimus  Fuchs  1915 

Dorsal  onch.  small,  deepset;  bursa  0;  in  exudate  chestnut  blight.  .(Diplogasteroides  de  Man  1912) 
Oesophageal  bulb  cardiac  only,  preceded  by  isthmus;  phar.  of  serial  plates;  bursa  0  or  reduced 
Head  with  6  large  odontia;  amphid  not  obscure,  often  large 

Nema  mostly  cephalated;  cirri  0;  amphid  circular;  soil  &  fresh  water.  .Teratocephalus  de  Man  1876 
Nema  not  cephalated;  cirri  6;  amph.  transverse-oval;  tail  hooked;  in  bark  Chambersiella  Cobb  1920 

(  =  Diastolaimus  Rahm  1928) 
Head  entire  or  3-parted  at  lips;  nema  not  cephalated,  exc.  Acrobeles  insubricus;  amph.  small 

Probolae  absent;  onchium  0,  or  1  inward-pointing Macrolaimus  Maupas  1900 

Probolae  on  head  in  1  or  2  circlets 

Circlets  of  probolae  2,  labial  and  cephalic;  amphid  a  pore  near  lips (Acrobeles  Linst.  1877) 

Circlet  of  probolae  single;  amphid  often  obscure Cephalobus  Bast.  1865 

(= Acrobeloides  (Cobb)  Steiner  &  Biihrer  1933) 
Ovaries  2 

Gonads  9  outstretched;  cephalic  setae  present;  marine  or  in  brackish  soil 
Amphid  multispire;  cephalic  setae  10,  unequal 
Cardiac  bulb  ellipsoid;  6  of  ceph.  set.  short;  subcephalic  setae  4;  tail  30%,  fine . . Laimella  Cobb  1920 

Cardiac  bulb  slight;  4  of  ceph.  set.  short,  tips  specialized;  tail  7% (Linhomoella  Cobb  1920) 

Amphid  circular  or  monospiral;  tail  not  over  18%,  not  setaceous 

Gland  ducts  cuticularized,  piercing  cuticle,  yentrad,  cerv.  &  pre-anal. .  Halaphanolaimus  Southern  1914 
Gland  ducts  and  pores  absent;  pharynx  minute  or  none 

Pharynx  inone;  ceph.  set.  10,  4  short,  tips  specialized;  tail  7% (Linhomoella  Cobb  1920) 

Pharynx  obconqid,  when  open  J-J  as  wide  as  head;  spinneret  sometimes  present 
Cuticularized  rings  in  pharynx  1-3;  neck  8-14%;  marine  &  brackish  soil  (Desmolaimus  de  Man  1880) 
Cuticularized  pharyngeal  rings  absent;  ventriculus  present;  marine 

Base  pharynx  not  cuticularized;  cardiac  bulb  oft  valvate;  head  iconoid  Cryptolaimus  Cobb  1933 
Base  pharynx  cuticularized;  cardiac  bulb  valvate;  head  ±cylindroid  Metalinhomoeus  de  Man  1907 

(cf.  Deltanema  Kreis  1929) 
Gonads  9  reflexed 

Habitat  not  marine,  exc.  rarely  Rhabditis  and  Haliplectus  (for  alternative  see  next  page) 
Oesophageal  bulbs  median  and  cardiac;  cephalic  setae  0;  pharynx  ±tubular  (for  alt.  see  next  page) 
Vulva21%;anus81%;  amph.  semicirc.,  \  head-width;  wings  &  bursa  none  (Aulolaimoides  Micol.  1915) 
Vulva  40-94%;  in  soil  etc.,  in  fresh  water,  and  marine 
Spinneret  pres.;amph.monospire,protruding;wings  &  bursa  0;pores  lateral.  .Haliplectus  Cobb  1913 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  477 

Spinneret  none;  cardiac  bulb  valvate;  amphid  obscure;  wings  and  bursa  present  Rhabditis  Duj.  1845 
Oesophageal  bulb  cardiac  only  (for  alternative  see  preceding  page) 
Spinneret  absent;  ampbid  circular,  elliptical  or  monospiral 

Head  without  odontia;  nema  not  cephalated;  setae  0;  spear  minute;  in  soil  (Triplonchium  Cobb  1920) 
Head  with  6  large  odontia;  bursa  none  or  much  reduced 

Nema  mostly  cephalated;  cirri  0;  amph.  circular;  in  soil  &  fresh  water. . .  Teratocephalus  de  Man  1876 
Nema  not  cephalated;  cirri  6;  amphid  transverse-oval ;  tail  hooked;  in  bark  Chambersiella  Cobb  1920 

(  =  Diastolaimus  Rahm  1928) 
Spinneret  present 

Pharynx  simple;  oesophagus  not  plectoid;  neck  15-20% 

Cephalic  setae  0;  wings  0;  pharynx  long;  amphid  with  pocket;  tail  27%  (Rhabdolaimus  de  Man  1880) 
Cephalic  setae  4;  pharynx  short;  tail  15% 

Wings  present;  amphid  monospire Paraphanolaimus  Micol.  1923 

Wings  absent;  amphid  circular;  onchium  minute,  not  at  lips Prodesmodora  Micol.  1923 

Pharynx  compound-elongate;  oes.  oft  with  isthmus  to  card,  bulb  (plectoid);  wings  pres. 
Labial  region  not  expanded;  cephalic  setae  usually  4,  sometimes  0  or  6;  neck  12-30% 
Cardiac  bulb  not  valvate;  pharynx  long;  neck  14-15%;  in  fresh  water  &  mud  Paraplectus  Fil.  1930 

Cardiac  bulb  valvate;  amphid  circular  or  transverse-oval Plectus  Bast.  1865 

Labial  region  expanded,  with  complicated  appendages;  pharynx  4-9%;  neck  27-31% 
Lips  6,  distinct,  revolute;  striae  fine;  amphid  semicircular;  pharynx  9%  (Anthonema  Cobb  1906) 
Lips  not  revolute;  head  with  dorso- ventral  bladders;  striae  coarse;  amph.  round;  phar.  3-6% 

Cephalic  appendages  elaborately  palmate Wilsonema  Cobb  1913 

Cephalic  appendages  forming  a  closed,  striated  dome  or  cupola.  .Bitholinema  de  Coninck  1931 
Habitat  marine  or  brackish  (for  alternative  see  preceding  page) 

Ambulatory  set.  forming  a  ventral  sole,  midbody  to  pre-anal;  nema  crooked;  calvarium  unstriated 
Nema  narrowest  in  card,  reg.,  ±S-shaped;  ambulatory  set.  hollow,  pre-anal;  annules  finer 
Oesoph.  region  hardly  swollen;  card,  bulb  faint;  cerv.  striae  alike  Notochaetosoma  Irwin-Smith  1918 
Oesoph.  region  swollen,  ovoid;  oesophageal  bulbs  1  or  2;  band  of  cervical 
striae  accentuated,  exc.  Tristicochaeta  falcatum 

Ventral  ambulatory  adhesion  tubes  or  setae  in  2  rows Drepanonema  Cobb  1933 

(  =  Chaetosoma  Clap.  1863) 

Ventral  ambulatory  adhesion  tubes  or  setae  in  3  or  4  rows Tristicochaeta  Panceri  1878 

(  =  Draconema  Cobb  1913) 
Nema  narrowest  midway,  epsilon-shaped;  ambulatory  setae  not  open  at  end;  annules  coarser 

Sole  apparently  absent;  amphid  cresentic;  annules  98 Epsilonella  Steiner  1930 

Sole  present;  amphid  circular  or  monospiral 

Oesophagus  with  median  and  cardiac  bulbs Metepsilonema  Steiner  1927 

Oesophagus  with  cardiac  bulb  only 

Annules  80-112;  ambulatory  setae  slender,  falcate Bathyepsilonema  Steiner  1927 

Annules  144-192;  ambulatory  setae  straight  or  slightly  arcuate 

Body  cylindroid,  if  crooked  faintly  so Archepsilonema  Steiner  1927 

Body  epsilon-like,  i.e.  body  arches  well  developed 

Cuticular  annules  homogeneous  in  structure Prochaetosoma  Baylis  &  Daubney  1926 

(  =  Rhabdogaster  Metsch.  1867) 
Cuticular  annules  not  homogeneous  in  structure 

"Axial"  part  of  the  cuticular  annules  hollow  ("frame  rings") Epsilonema  Steiner  1927 

"Axial"  part  of  the  cuticular  annules  vacuolated,  etc Epsilonoides  Steiner  1931 

Ambulatory  setae  0;  nema  not  crooked;  calvarium  absent,  or  not  truncate-conoid 
Lips  2,mouthaslit;amph.faintmultispire;"pseudonchs"dorso-ventral  ridges  Pseudonchus  Cobb  1920 
Lips  not  2,  mouth  not  a  slit;  "pseudonchs"  absent 
Amphid  multispire;  neck  9-13% 
Pharynx  deeper  than  head  width,  wall  irregular,  with  projections;  striae  plain  Zalonema  Cobb  1920 

Pharynx  tubular,  less  deep,  wall  straight;  striae  of  dots Kreisia  Allgen  1929 

Amphid  circular,  elliptical  or  monospiral;  neck  14-25%,  exc.  Bolbonema  8% 
Wings  present;  anterior  end  set  off  by  groove  at  4  ceph.  set.  &  usually  by  lack  of  annulation 
Neck  20-25% 

Species  marine;  striae  duplex;  wings  2;  phar.  tubular,  inconspic.,  prob.  double  Aplectus  Cobb  1914 
Species  in  brackish  soil  &  marsh;  lip  reg.  discoid;  ceph.  set.  papilloid.  .Leptolaimus  de  Man  1876 
Neck  14-16%;  marine 

Gland  ducts  cuticularized,  piercing  cuticle,  cerv.  and  pre-anal. .  Halaphanolaimus  Southern  1914 
Gland  ducts  &  pores  0;  pharynx  of  several  long  chambers;  amphid  round  Polylaimium  Cobb  1920 
Wings  absent 

Median  bulb  present;  ceph.  set.  0;  amph.  protruding:  neck  12%;  pores  lateral  Haliplectus  Cobb  1913 
Median  bulb  absent;  pores  none;  marine 

Nema  cephalated  by  expansion  opposite  large  monospiral  ampbid;  neck  8%  Bolbonema  Cobb  1920 
Nema  not  cephalated  by  expansion 

Setae  on  head  6-10,  long,  flexible;  neck  under  5%:  pharyngeal  bulb  present. .  (Laxus  Cobb  1894) 
Setae  on  head  0-4;  neck  6%  or  over;  pharyngeal  bulb  absent 
Head  constricted  at  cephalic  setae,  not  at  amphid;  amphid  2  head-widths  back 
Chambers  of  pharynx  several,  long;  neck  10-11%;  cephalic  setae  0(?)  Polylaimium  Cobb  1920 
Chamber  of  pharynx  single;  neck  19%;  head  conoid;  cephalic  set.  4  Dermatolaimus  Steiner  1916 
Head  not  constricted  at  setae;  amphid  near  lips  or  not  over  1  head-width  back 
Ceph.set.0;phar.a  tube  reaching  card. bulb ;amphid  conspicuous. .  Aegialoalaimus  de  Man  1907 

Amphid  small.monospiral.at  lips;neck  19%;dorsal  phar.wall  thickened  (Onchium  Cobb  1920) 
Amphid  conspicuous, round, not  at  lips;neck  6%;phar.wall  not  thick.  .Linolaimus  Cobb  1933 
Oesophagus  plain,  i.e.  without  median  or  posterior  bulb  or  swelling  (for  alternative  see  page  474) 
Amphid  not  known  or  obscure  (for  alternative  see  next  page) 
Female  not  known;  marine  (for  alternative  see  next  page) 

Neck  over  40%;  amphid  a  long,  slit;  ceph.  setae  4  or  8,  fine;  spinneret  oft  none. .  (Halalaimoides  Cobb  1933) 
Neck  10-30%;  amphid  not  longitudinal;  spinneret  present  (Trileptium,  Fimbriella  ?) 

Cephalic  setae  0;  onchia  3,  awl-shaped,  almost  parallel  to  axis (Fimbrilla  Cobb  1905) 

(  =  Fimbria  Cobb  1894) 
Cephalic  setae  8  or  more 

Onchium  dorsal,anterior,inward-pointing;neck  12%;nema0.5%  wide;amph.  asht  (Tnleptium  Cobb  1923) 

( =  Trilepta  Cobb  1920) 
Onchium  none;  neck  22-30%;  nema  2-3%  wide;  cephalic  setae  usually  8,  in  2  circlets 


478  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Calvarium  present;  setae  8,  near  base  of  pharynx;  eyes  present Gullmarm'.a  Allgen  1929 

Calvarium  absent;  setae  minute,  around  mouth;  eyes  0;  pharynx  small,  tubular.  .Fimbriella  Allgen  1929 
Female  known  (for  alternative  see  preceding  page) 
Ovary  1,  anterior 

Ceph.  set.  4;  pharynx  large,  open;  spinneret  present;  spicula  2-jointed(?);  marine.  ..Filipjeva  Ditlev.  1928 
Ceph.  set.  0  or  papilloid;  pharynx  none  or  narrow;  spinneret  usually  none;  ~9 

Pharynx  a  tube  reaching  halfway  to  nerve  ring;  in  soil Gymnolaimus  Cobb  1913 

Pharynx  closed,  or  marked  by  reduced  spear,  not  over  J  distance  to  nerve  ring 

Nema  free-living,  marine;  spinneret  doubtful;  pharynx  none  or  closed Litotes  Cobb  1920 

Nema  parasitic  in  insects;  spinneret  0;  adult  spear  reduced,  base  3-parted. .  (Aphelenchulus  Cobb  1920) 
Ovaries  2 
Gonads  9  outstretched;  spinneret  present;  marine 

The  ovaries  extending  backward;  winge  10-12;  vulva  45% Porocoma  Cobb  1920 

The  ovaries  opposed;  wings  0 

Annules  none  or  not  coarse;  amphid  not  saccate,  far  back;  nema  not  wide. . . .  Anoplostoma  Butsch.  1874 
Annules  coarse;  amphid  saccate;  nema  wide;  cephalic  setae  4 

Number  annules  ±17,  secreted  annules  prominent,  separated;  head  small .. Desmoscolex  Clap.  1863 
Number  annules  32-91,  secreted  annules  0;  head  concave-quadrate  pyramidal.  .Tricoma  Cobb  1894 

(  =  Quadricoma  Fil.  1922) 
Gonads  9  reflexed 

Spinneret  none;  wings  0;  pharynx  2.5-3%,  tubular;  tail  rounded,  under  2%;  in  soil.  .Isolaimium  Cobb  1920 
Spinneret  present 

Habitat  freshwater;  lips  thick;  pharynx  closed;  amphid  small;  onch.  small,  deepset  (Tripyla  Bast.  1865) 

(=Promononchus  Micol.  1923) 
Habitat  marine 

Annules  ±17,secreted  annules  prominent;amph.saccate;nema  wide;ceph.set.4.  .Desmoscolex  Clap.  1863 
Annules  none;  amphid  not  saccate;  nema  less  than  5%  wide 
Dorsal  pharyngeal  wall  bent  inward  at  lips,onchium-like;ceph.setae  10.  .(Asymmetrella  Cobb  1920) 

Dorsal  pharyngeal  wall  not  onchium-like;  cephalic  setae  0 Angustinema  Cobb  1933 

Amphid  known  (for  alternative  see  preceding  page) 

External  amphid  not  spiral ,  circular  nor  elliptical  (for  alternative  see  next  page) 
Female  not  known;  Enoplidae  (Trileptium  ?) 

Head  mitreform,  set  off  by  constriction;  wings  6-8;  spinneret  doubtful;  marine Xennella  Cobb  1920 

Head  not  mitreform;  spinneret  often  absent 

Ceph.  set.  0:  ext.  amph.wide,curved;phar.tubular,halfway  to  nerve  ring ;fresh water  Colpurella  Cobb  1920 
Ceph.  set.  present;  amphid  small,  or  long  and  narrow;  marine 

Amphid  narrow,many  head-widths  long  ;neck  ±40%  ;ceph.set.4-8;tail  setaceous  Halalaimoides  Cobb  1933 
Amphid  small,  transverse-oval;  neck  25%  or  less 

Neck  25%;onchium  no ne;ceph. setae  6 .small, inconspicuous ;spinneret  present. .  Vasculonema  Kreis  1928 

(cf.  Pelagonema  Cobb  1894) 

Neck  12%;  onchium  dorsal;  cephalic  setae  10,  conspicuous;  labial  setae  6 . . . .  Trileptium  Cobb  1933 

(  =  Trilepta  Cobb  1920) 
Female  known 
Ovary  1(  anterior 

Gonad  9  outstretched ;pharynx  closed;ceph.set.papilloid;spinneret  doubtful  ;marine.  .Litotes  Cobb  1920 
Gonad  9  reflexed;  spinneret  present;  external  amphid  a  transverse  slit,  not  at  lips;  not  marine 

Onchia  0;  amphid  far  behind  the  ±quadrate  pharynx;  in  fresh  water Prismatolaimus  de  Man  1880 

Onchium  minute,  deepset;  amphid  opposite  pharynx;  in  soil  about  roots 

Pharynx  conoid  when  open;  amphid  opposite  base  of  pharynx (Trischistoma  Cobb  1913) 

Pharynx  a  long  tube,  amphid  opposite  its  anterior  end,  with  pocket Cryptonchus  Cobb  1913 

(  =  Dilletsenia  Micol.  1925) 
Ovaries  2;  marine  exc.  Monhystera 
Gonads  9  outstretched 
Spinneret  absent 

Habitat  marine;  amphid  long-oval,  on  large  triangular  plate Didelta  Cobb  1920 

Habitat  not  marine;  amphid  a  transverse  slit;  in  soil  about  roots Monhystera  Bast.  1865 

(=M.  dintheriana  de  Man  1885) 
Spinneret  present 

Mouth  opening  ±ventrad;wing  duplex ;amph. big, bent, dorsal  arm  the  longer  (Campylaimus  Cobb  1920) 
Mouth  opening  axial,  terminal;  wings  none  exc.  sometimes  Pseudolella 
Annules  coarse;  amphid  saccate;  nema  wide;  cephalic  setae  4 

Number  of  annules  ±17,  secreted  annules  prominent,  separated;  head  small. .  Desmoscolex  Clap.  1863 
Number  of  annules  32-91,  secreted  annules  0;  head  concave-quadrate  pyramidal . .  Tricoma  Cobb  1894 

(  =  Quadricoma  Fil.  1922) 
Annules  none,  striae  fine;  amphid  not  saccate;  nema  slender 

Amphid  small,  opening  transverse  with  internal  pocket,  far  back (Anoplostoma  Butsch.  1874) 

Amphid  shepherd's  crook,  dorsal  arm  the  longer 

Length  of  amphid  extreme,  sometimes  exceeding  neck;  eyes  0 (Pseudolella  Cobb  1920) 

Length  of  amphid  not  over  1  head-width,  loop-shaped;  eyes  2,  sometimes  none 
Oesophagus  &  lumen  widened  between  eyes  and  nerve  ring;pharynx  obvious  Coinonema  Cobb  1920 
Oesophagus  &  lumen  not  widened;  pharynx  like  oesophagus. . .  Araeolaimoides  (de  Man)  Fil.  1918 
Gonads  9  reflexed 
Spinneret  absent;  amphid  with  internal  pocket 

Cephalic  setae  0;  pharynx  2-3%,  tubular;  tail  rounded,  under  2%;  in  soil Isolaimium  Cobb  1920 

Cephalic  setae  10,  subcephalic  many;  marine Platycomopsis  Ditlev.  1926 

(  =  DactVlonema  Fil.  1927) 
Spinneret  present 

Habitat  freshwater;  amphid  usually  small  or  inconspicuous 

Pharynx  wide.domedby  thin  lips  ;onch.0;amph.transverseslit,far  back.  .Prismatolaimus  de  Man  1880 
Pharynx  closed, lips  thickionch. minute, deepset ;external  amphid  round  or  oval.  .(Tripyla  Bast.  1865) 

(  =  Promononchus  Micol.  1923) 
Habitat  marine 

Cephalic  setae  none  or  papilloid;  external  amphid  narrow,  transverse  (for  alt.  see  next  page) 
Amphid  J  head-width;  cuticle  i  radius,  annules  coarse,  markings  rod-like.  .(Actinonema  Cobb  1920) 
Amphid  f  head-width  or  less,  with  internal  pocket ;  cuticle  less  thick ;  phar.  with  lumen ;  Enoplidae 
Eyes  2;  protrusile  pharyngeal  ribs  none Illium  Cobb  1920 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  479 

Eyes  0;  protrusile  pharyngeal  ribs  3,  straight Fimbrilla  Cobb  1905 

„     ,    ..  (  =  Fimbria  Cobb  1894) 

Cephalic  setae  present,  not  papilloid  (for  alternative  see  preceding  page) 
Amphid  shepherd's  crook 

Annules  not  of  tile-like  elements Parachromagaster  Allgen  1929 

Annules  coarse,  each  of  8  tile-like  elements Ceramonema  Cobb  1920 

(cf.  Pselionema  Cobb  1933) 
Amphid  not  shepherd  s  crook 

Nemawide;annules±17,secreted  annules obvious ;amph.saccate;ceph.set.4.  .Desmoscolex  Clap.  1863 
Nema  slender,  under  5%;  amphid  not  saccate;  annules  0,  striae  fine  or  0;  Enoplidae 
Onchium  dorsal;  labial  setae  0;  cephalic  setae  10,  near  lips 

Tooth  vestigial,  on  wall;  external  amphid  a  small  slit;  eyes  0 (Anoncholaimus  Cobb  1920) 

Tooth  a  bending  inward  of  dorsal  pharyng.wall;amphid  larger.faint. .  (Asymmetrella  Cobb  1920) 
Onchia  none;  labial  setae  6,  obvious;  cephalic  setae  10  or  more,  length  1-5  times  head  width 
Pharynx  narrow,closed;odontia  (?)  minute;ceph.set.3  times  head  width  (Tubolaimella  Cobb  1933) 
Pharynx  wide,  open;  odontia  none 

Lips  3,  deep-cleft,  with  frame  work;  ceph.  set.  2-5  times  head  width Chaetonema  Fil.  1927 

Lips  without  framework;  ceph.  set.  1  head-width;  excret.  pore  raised. .  (Paranticoma  Micol.  1930) 
External  amphid  spiral,  circular  or  elliptical  (for  alternative  see  preceding  page) 
Female  not  known;  spinneret  present;  marine 

Nema  wide,  14-32%,  widest  at  lip  region,  tapering  to  terminus;  wings  numerous.  .Pteronium  Cobb  1933 
Nema  slender,  not  over  5%  wide,  widest  near  middle 

Amphid  multispire;  wings  0;  cephalic  &  labial  setae  18;  labial  framework  present. . .  .Dispira  Cobb  1933 
Amphid  circular,  elliptical  or  monospiral 

Odontia  2,  large,  lateral  or  subventral (Diodontolaimus  Southern  1914) 

Odontia  absent(in  Stephanolaimus  6  minute?) 

Onchium  ventral ;  cephalic  setae  10;  am  ph.  i  head-width,  with  internal  pocket. .  (Isonemella  Cobb  1920) 
Onchium  absent  (Nudolaimus  ?) 

Calvarium  reduced  to  submed.plates;phar.large,wall  strong/'onchia"  basal.  .Nudolaimus  Allgen  1929 
Calvarium  absent;  cephalic  setae  present 
Wings  present;  cephalic  setae  6  or  10 

Ceph.  set.  6;  wings  8;  annules  coarse,  elements  tile-like;  oesoph.  compound.. Dasynemella  Cobb  1933 

(  =  Dasynema  Cobb  1920) 

Ceph.  set.  10;  wings  2;  oesophagus  simple;  pharynx  iquadrate Pulchranemella  Cobb  1933 

Wings  absent;  cephalic  setae  4-8 

Lip  region  discoid,  set  off  by  constriction;  odontia(?)  6 Stephanolaimus  Ditlev.  1918 

Lip  region  not  discoid;  cephalic  setae  4  or  6 

ng.  vestibule  with  rod-like  supports;  head  ±cylindroid;  striae  0;  ceph.  set.  4 

6,  straight,  parallel  to  body  axis;  cephalic  setae  4,  jointed Rhadinema  Cobb  1920 

Rods  more  than  6,  curved,  meeting  axially Eleutherolaimus  Fil.  1922 

Pharyng.  vestibule  without  supports;  striae  pres.  exc.  Vasculonema  &  Bathylaimella 
Amphid  transverse-oval,  near  lips;  head  slightly  conoid;  setae  small 

Setae  labial,  cephalic  and  subcephalic,  minute Zygonemella  Cobb  1920 

.  Setae  cephalic  only,  6,  small,  inconspicuous Vasculonema  Kreis  1928 

(cf.  Pelagonema  Cobb  1894) 
Amphid  circular,  near  base  of  wide-tubular  pharynx 

Head  cylindroid;  setae  on  head  16,  longest  4  times  head  width Cenolaimus  Cobb  1933 

Head  conoid,  narrowing  50%  from  base;  setae  on  head  4,  short 

Cuticle  striated;  width  (compressed  ?)  6% Tubolaimus  Allgen  1929 

Cuticle  not  striated;  width  3% Bathylaimella  Allgen  1930 

Female  known 

Ovary  1  (for  alternative  see  next  page) 
Gonad  9  reflexed 

Amphid  multispire;  ovary  posterior;  pharynx  linear;  spinneret  doubtful;  marine  Alaimella  Co,bb  1920 
Amphid  not  multispire;  ovary  anterior 

Spinneret  none;  amph.  round,  with  central  mound;  caudal  setae  thorn-like,  2  rows  (Zanema  Cobb  1920) 
Spinneret  present;  tail  without  thorn-like  setae 

Habitat  marine;  pharynx  tubular;  cephalic  setae  4;  nema  ±2%  wide (Conolaimella  Allgen  1930) 

Habitat  not  marine;  pharynx  open,  not  small  nor  narrow;  nema  2-5%  wide 

Cephalic  setae  4 ;  pharynx  with  supporting  pieces;  amph.  monospire;  fresh- water  Anonchus  Cobb  1913 
Cephalic  setae  6  or  10,  papilloid  in  Tripylium 

Amphid  monospire;  in  gills  of  land  crabs (Tripylium  Cobb  1920) 

Amphid  small,  circular,  transverse-oval  or  slit-like 

Onchium  0;  pharynx  ±quadrate;  amphid  far  back;  in  fresh  water Prismatolaimus  de  Man  1880 

Onchium  minute,  deepset;  pharynx  conoid;  amphid  opp.  pharynx;  in  soil  (Trischistoma  Cobb  1920) 
Gonad  9  outstretched 
Habitat  not  marine 

Spear  minute;  spinneret  none;  bursa  present;  parasitic  in  beetle (Aphelenchulus  Cobb  1920) 

Spear  absent;  bursa  absent;  in  fresh  water Cylindrolaimus  de  Man  1880 

Habitat  marine 

External  amphid  multispire;  pharynx  linear;  tail  ±10%;  spinneret  doubtful  (Alaimella  Cobb  1920) 

External  amphid  circular,  pocket  elongate;  tail  34%;  spinneret  none Halanonchus  Cobb  1920 

The  ovary  anterior 

Cephalic  setae  4,  papilloid;  pharynx  obscure,  linear;  amphid  faint,  open  caudad Litotes  Cobb  1920 

Cephalic  setae  not  papilloid 
Spinneret  absent;  labial  appendages  ("palps")  present;  amphid  circular 

Tail  with  2  rows  of  thorn-like  setae;  amphid  with  distinct  central  mound Zanema  Cobb  1920 

Tail  without  thorn-like  setae;  amphid  without  mound;  cardiac  bulb  faint  Crystallonema  Cobb  1920 
Spinneret  present ;  amphid  circular  or  monospire 

Pharynx  7%,  tubular  ,±halfway  to  nerve  ring;  head  narrow ;  amphid  far  back  Rhynconema  Cobb  1920 
Pharynx  less  than  2%,  not  a  long  tube 
Depth  of  pharynx  much  greater  than  width,  pharynx  small 

Oesophagus   almost   surrounding   conoid   pharynx Conolaimella   Allgen  193 

Oesophagus  meeting  base  of  obconoid  pharynx Sphaerocephalum  Fil.  1918 

Depth  of  pharynx  not  much  greater  than  width,  pharynx  large,  open 


480  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

Amphid  ±1  head-width;  vulva  59%;  caudal  set.  stiff,  8  prs.;  post,  ovary  small  Halinema  Cobb  1920 
Amphid  ±i  head-width;  vulva  80^85% ;  caudal  set.  0;  lips  6,  conoid,  separate 

Labial  setae  6,  hook-shaped,  on  tips  of  lips;  amphid  spiral;  in  mud (Dactylaimus  Cobb  1920) 

Labial  setae  6,  not  hook-shaped  nor  at  tips;  amphid  round;  cepb.  set.  18.  .Omicronema  Cobb  1920 
Ovaries  2  (for  alternative  see  preceding  page) 
Gonads  9  outstretched:  usually  marine 
Spinneret  absent;  marine  exc.  Pseudoaulqlaimus 

Habitat  mud,  rice  fields;  wings  16-32,  fusing  to  4  on  4-pronged  tail Pseudoaulolaimus  Imamura  1931 

Habitat  marine 

Amphid  long  oval,  on  wide  triangular  plate,  almost  as  long  as  head  is  wide Didelta  Cobb  1920 

Amphid  smaller,  not  on  triangular  plate 

Cervical  setae  bunched;  2  flat  setae  in  front  of  transverse-oval  amphid (Platycoma  Cobb  1894) 

Cervical  setae  if  present  not  bunched;  amphid  ±circular 

Pharynx  long,  simple,  tubular;  cephalic  setae  6 Southerniella  Allgen  1932 

Pharynx  minute;  ceph.  set.  18,  minute,  in  2  circlets;  amphid  faint  multispire  Anticyathus  Cobb  1920 
Spinneret  present;  marine  exc.  Cylindrolaimus 

Habitat  freshwater;  ceph.  set.  4;  ovaries  usually  unequal;  pharynx  tubular  Cylindrolaimus  de  Man  1880 
Habitat  marine 

Annules  few,  coarse;  amphid  saccate;  cephalic  setae  4;  nema  wide 

Number  annules  ±17,  secreted  annules  prominent,  separated;  head  small. . Desmoscolex  Clap.  1863 
Number  annules  32-91,  secreted  annules  none;  head  concave-quadrate  pyramidal  Tricoma  Cobb  1894 

(  =  Quadricoma  Fil.  1922) 
Annules  if  present  not  few  nor  coarse;  amphid  not  saccate 

Gland  ducts  cuticularized,  pores  cervical  &  pre-anal ;  striae  coarse Halaphanolaimus  Southern  1914 

Gland  ducts  and  pores  absent 
Cephalic  setae  10  or  more 
Pharynx  with  transverse  cuticularized  ring 
Cavity  of  pharynx  simple,  capacious,  ±cylindroid,  J  head-width. . .  .Eumorpholaimus  Schulz  1932 

Cavity  of  pharynx  small,  cup-shaped,  rings  sometimes  2  or  more (Linhomoeus  Bast.  1865) 

(i.e.  subg.  Paralinhomoeus  de  Man  1907 
=  Paradesmolaimus  Schulz  1932) 
Pharynx  without  transverse  cuticularized  rings 

Longest  ceph.  set.  4,  total  16,  tips  simple;phar.  quadrate  ;amph.  ±neck-width  Halinema  Cobb  1920 
Longest  ceph.  set.  6,  4  short  specialized  at  tip;  phar.  0(7);  multispire  faint  Linhomoella  Cobb  1920 
Cephalic  setae  4 
Nema  wide,  10-16%;  wings  numerous;  neck  region  "collared" ;  amphid  spiral;  Richtersiinae 

Wings  ±50;  pharynx  narrow;  spicula  2,  equal Richtersia  Steiner  1916 

Wings  16-32;  pharynx  capacious,  open;  spicula  unequal,  or  1  only Richtersiella  Kreis  1929 

Nema  slender,  under  5%;  wings  if  present  not  numerous 

Eyes  absent;  amphid  circular;  pharynx  truncate  at  base Bathylaimella  Allgen  1930 

Eyes  often  present;  setae  behind  head  usually  long,  numerous,  conspicuous 

Oesophagus  lumen  not  enlarged;  amphid  loop-shaped (Araeolaimoides  (de  Man)  Fil.  1918) 

Oesophagus  and  lumen  widened  between  eyes  and  nerve  ring;  pharynx  obvious 

Shape  of  amphid  loop-like  ("folded") (Cmnonema  Cobb  1920) 

Shape  of  amphid  circular  or  monospiral;  eyes  sometimes  absent(?) . . .  Araeolaimus  de  Man  1888 
Gonads  9  reflexed 

Spinneret  absent;  amphid  circular,  elliptical  or  monospiral 
Habitat  not  marine;  pharynx  long,  tubular,  ±half  as  long  as  oesophagus 

Wings  16-32,  conspic.,  fusing  to  4  on  4-pronged  tail;  in  rice  fields Pseudoaulolaimus  Imamura  1931 

Wings  0;  end  of  tail  not  4-parted;  in  soil Isolaimium  Cobb  1920 

Habitat  marine;  pharynx  short 

Pharynx  narrow;  amphid  ±flattened,  preceded  by  2  flat  setae Platycoma  Cobb  1894 

Pharynx  0  or  linear;  amphid  transverse-oval,  with  pocket,  4  set.  posterior. .  Platycomopsia  Ditlev.  1926 

(  =  Dactylonema  Fil.  1927) 
Spinneret  present 
Habitat  freshwater 

Mouth  cavity  absent  or  obscure,  closed 
Amphid  monospire;  gland  cells  lateral;  d"  supplements  protrusile  tubes. .  Aphanolaimus  de  Man  1880 

Amphid  circular  or  elliptical;  cf  supplements  not  protrusile Tripyla  Bast.  1865 

(  =  ProwononcAusMicol.  1923) 
Mouth  cavity  definite,  open,  obvious 

Pharynx  narrow,  compound;  amphid  monospire,  J  head-width;  cephalic  setae  4  Paraplectus  Fil.  1930 
Pharynx  simple,  i.e.  of  1  chamber 

The  amphid  small,  transverse-oval  or  a  slit;  cephalic  setae  6  or  10. .  .Prismatolaimus  de   Man  1880 
The  amphid  monospire,  opp.  pharynx;  cepb.  setae  4;  gland  cells  lateral  Paraphanolaimus  Micol.  1923 
Habitat  marine 
Nema  wide,  over  10% 
Annules  few,  coarse;  amphid  saccate 

Body  setae  not  dense;  secreted  annules  prominent,  separate;  head  small.  .Desmoscolex  Clap.  1863 
Body  setae  dense,  set  along  annules;  junct.  oesoph.  &  intestine  indefinite. .  .Greeffiella  Cobb  1922 

(  =  TTichoderma  Greeff  1869) 
Annules  if  present  many ;  longitudinal  ridges  or  wings  16-50;  neck  "collared" ;  Richtersiinae 

Wings  ±50;  pharynx  narrow;  spicula  2,  equal Richtersia  Steiner  1916 

Wings  16-32;  pharynx  wide,  capacious;  spicula  unequal,  or  1  only Richtersiella  Kreis  1929 

Nema  slender,  not  over  5% 
Calvarium  present  as  a  band  or  plates 

Oesophagus  not  crenate ;  calyarium  of  plates ;  gland  cells  lateral Cylicolaimus  de  Man  1889 

Oesophagus  crenate;  calvarium  a  band (Phanodermopsis  Ditlev.  1926) 

(  =  Galeonema  Fil.  1927) 
Calvarium  absent 

Gland  ducts  cuticularized,  pores  cervical  &  pre-anal;  striae  coarse. .  (Halaphanolaimus  Southern  1914) 
Gland  ducts  and  pores  none,  or  not  cuticularized 

Denticles  mid-phar.,  apophyses  forward  &  back;  amph.  multispire  (Halichoanolaimus  de  Man  1886) 

(=Smalsundia  Allgen  1929) 
Denticles  none:  amphid  not  multispire 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  481 

Pharynx  open,  wide,  icapacious 

Amphid  round ;  anterior  pharyng.  chamber  large,  posterior  small ;  setae  10  Bathylaimus  Cobb  1894 

(  =  Macrolaimus  Ditlev.  1918 
=  Cothonolaimus  Ditlev.  1919) 

Amphid  small,  with  internal  pocket  (Pandolaimus  ?);  pharynx  of  1  chamber 
Depth  pharynx  iequalling  width;  dorsal  onch.  small,  ant.,  appressed  Anoncholaimus  Cobb  1920 
Depth  pharynx  nearly  twice  width 

Wall  of  pharynx  irregularly  thick;  amphid  apparently  circular Pandolaimvs  Allgen  1929 

Wall  of  pharynx  thin;  amphid  small,  transverse-oval,  with  pocket Pelagonema  Cobb  1894 

(cf.  Vasculonema  Kreis  1928) 

Pharynx  narrow,  often  tubular  or  with  closed  lumen 
The  amphid  behind  level  of  cephalic  setae 

Cephalic  setae  0;  pharynx  $  head-width,  with  3  refractive  elements. . .  Angustinema  Cobb  1933 
Cephalic  setae  present 

Nema  over  3  mm.  long Cynwa  Cobb  1920 

Nema  0.6  mm.  long Aplectus  Cobb  1914 

The  amphid  in  front  of  level  of  cephalic  setae;  cephalic  setae  4 

Dorsal  pharyng.  wall  not  thicker;  ampbidial  glands  large,  conspic.;  eyes  2  . .  .lonema  Cobb  1920 
Dorsal  pharyng.  wall  thick,  tooth-like;  amph.  monospire  at  lips ;  re  net  te  far  back 
Oesoph.  glands  obscuring  junct.  of  intest. ;  dorsal  phar.  element  uniform. .  .Onchium  Cobb  1920 
Oesoph.  glands  not  prominent;  dorsal  pharyng.  element  not  uniformly  thick,  but  heavy 

Tooth-like  thickening  parallel  to  axis Camacolaimus  de  Man  1889 

(^Digitonchus  Cobb  1920 
=  Acontiolaimus  Fil.  1918) 
Tooth-like  thickening  bent  outward  from  beginning  of  vestibule 

Point  of  "onchium"  single Acmaeolaimus    Fil.  1918 

Point  of  Y-shaped  "onchium"  duplex Ypsilon  Cobb  1920 


482  PROCEEDINGS   HELMINTHOLOGICAL   SOCIETY  VOL.  2,  NO.  1 

LITERATURE  CITED 

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Mag.  Naturvidenskaberne.    66:  305-306.     1927. 
• —    Sudschwedische  marine  Nematoden.     Goteborgs  K.  Vetensk.  O.  Vetterhets  = 

Samhalles.     Handl.  Ser.  B  1:  29.     1929. 
Neue  freilebende  marine  Nematoden  von  der  Westkuste  Schwedens.     Zool.  Jahrb. 

Abt.  System.  6'kol.  u.  Geogr.  Tiere.    57:  433-434,  436-437,  445,  454,  461,  466,  467, 

481,  491,  492,  493.     1929. 
Conolaimella,  ein  neues  Genus  mariner  Nematoden  von  der  Westkuste  Schwedens. 

Zool.  Anz.    88:  138.     1930. 

Freilebende  marine  Nematoden  von  der  Stateninsel   (Feuerland-Archipel.)   I. 

Zool.  Anz.    89:  257.     1930. 

Freilebende  marine  Nematoden  von  der  Stateninsel  (Feuerland-Archipel.)  II. 

Zool.  Anz.    90:  28.    1930. 

Weitere  Beitrage  zur  Kenntnis  der  marinen  Nematodenfauna  der  Campbellinsel. 

Nyt.  Mag.  Naturv.    70:  186.     1932. 

Ueber  einige  freilebende  marine  Nematoden  aus  der  Umgebung  der  Biologischen 


Station  auf  der  Insel  Herdla  (Norwegen)  mit  Anhang;  zur  Richtigstellung  alter er  und 
neuerer  mariner  Nematodengenera  I.  Arch.  Naturgesch.  1 :  424,  432.  1932. 

BASTIAN,  H.  C.  Monograph  on  the  Anguillulidae,  or  free  nematodes,  marine,  land,  and 
fresh  water;  with  descriptions  of  100  new  species.  Trans.  Linn.  Soc.  London  25:  97, 
100-101,  103-104,  115,  118,  121-122,  124,  125-126,  132,  141,  142-143,  144,  145,  154-155, 
156,  157,  158,  159,  162-163,  165,  167,  178.  1865. 

BATLIS,  H.  A.  AND  DAUBNEY,  R.  A  synopsis  of  the  families  and  genera  of  Nematoda. 
London.  Pp.  107,  112.  1926. 

BOVIEN,  P.  On  a  new  nematode,  Scatonema  wiilkeri  gen.  et  sp.  n.  parasitic  in  the  body- 
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Naturhist.  For.  Kj0benhavn.  94:  15-31.  1932. 

BirrscHLi,  O.  Zur  Kenntniss  der  freilebenden  Nematoden.  Abhandl.  Senckenb.  Naturf . 
Gesell.  Frankfurt  a.  M.  9:  270-273,  285.  1874. 

CARTJS,  J.  V.  Icones  zootomicae.  Erste  Half te:  Die  wirbellosenThiere.  Leipzig.  PI.  8, 
Fig.  1.  1857. 

CHITWOOD,  B.  G.  Helminthological  Society  Proceedings.  The  Journal  of  Parasitology. 
19:  243.  1933. 

CHRISTIE,  J.  R.  AND  CHITWOOD,  B.  G.  Chondronema  passali  (Leidy,  1852)  n.g.  (Nema- 
toda), with  notes  on  its  life  history.  Jour.  Wash.  Acad.  Sci.  21 :  357.  1931. 

CLAPAREDE,  E.  Beobachtungen  uber  Anatomic  und  Entwicklungsgeschichte  wirbelloser 
Thiere  an  der  Kuste  von  Normandie  angestellt.  Pp.  88-90.  1863. 

COBB,  M.  V.  Some  fresh-water  nematodes  of  the  Douglas  Lake  Region  of  Michigan, 
U.S.A.  Amer.  Micros.  Soc.  Trans.  34:  28-29.  1915. 

-  (edited  by)  N.  A.  Cobb:  New  nemic  genera  and  species,  with  taxonomic  notes. 
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COBB,  N.  A.  Onyx  and  Dipeltis:  New  nematode  genera,  with  a  note  on  Dorylaimus. 
Linn.  Soc.  N.  S.  Wales,  Proc.  6:  146-153,  155.  1891. 

Plant  diseases  and  their  remedies.     (III.  Nematode  worms  found  attacking  sugar- 
cane.)   Agric.  Gaz.  N.  S.  Wales.     Pp.  811,  819-820,  821,  825.     1893. 

-  Tricoma  and  other  new  nematode  genera.    Linn.  Soc.  N.  S.  Wales,  Proc.  (1893) 
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Australian  free-living  marine  nematodes.     Linn.  Soc.  N.  S.  Wales,  Proc.  (s.  1). 


23:  406-107.     1898. 


COBB:  A  KEY  TO  THE  GENERA  OF  FREE-LIVING  NEMAS  483 

COBB,  N.  A.     1905.    See  Stiles  and  Hassall,  1905. 

Fungus  maladies  of  the  sugar  cane,  with  notes  on  associated  insects  and  nema- 
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2nd  ed.,  pp.  187-189.  1906. 

Draconema:  A  remarkable  genus  of  marine  free-living  nematodes.     Jour.  Wash. 

Acad.  Sci.    3:  146-149.     1913. 

Notes  on  Mononchus  and  Tylenchulus.    Jour.  Wash.  Acad.  Sci.    3:287.     1913. 

-  New  nematode  genera  found  inhabiting  fresh  water  and  non-brackish  soils.    Jour. 
Wash.  Acad.  Sci.    3:  436-444.     1913. 

• Antarctic  marine  free-living  nematodes  of  the  Shackleton  Expedition.     Contrib. 

Sci.  Nematol.  I,  pp.  12, 16.     1914. 
• North  American  free-living  fresh-water  nematodes.     Amer.  Micros.  Soc.  Trans. 

33:  92-94.     1914. 

Selachinema  a  new  nematode  genus  with  remarkable  mandibles.     Contrib.  Sci. 

Nematol.  IV,  p.  113.     1915. 

• Notes  on  nemas.    Contrib.  Sci.  Nematol.  V,  pp.  118,  119.     1917. 

Filter-bed  nemas:  Nematodes  of  the  slow  sand  filter  beds  of  American  cities  (in- 
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Contrib.  Sci.  Nematol.  VII,  pp.  195-196,  203.     1918. 

-  One  hundred  new  nemas  (type  species  of  100  new  genera).     Contrib.  Sci.  Nematol. 
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-  Howardula  benigna,  a  nema  parasite  of  the  cucumber-beetle  (Diabrotica).     Con- 
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-  Marionella  (Eurystoma  Marion,  1870);  an  emendation,  with  notes  on  a  new 
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Sci.     11:  504-509.     1922. 

-  Greeffiella.    Jour.  Wash.  Acad.  Sci.     12:  299-303.     1922. 

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Marine  free-living  nemas.     Australas.  Antarc.  Exped.  1911-14.     Scient.  Rep., 

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The  demanian  vessels  in  nemas  of  the  genus  Oncholaimus;  with  notes  on  four  new 


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DE  CONINCK,  L.     Sur  trois  especes  nouvelles  de  nematodes  libres  trouves  en  Belgique. 

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INDEX 


page 
Acanthonchus  462 
Acanthopharynx  463 
Achromadora  465,  466 
Acmaeolaimus  462,  465,  471, 
474,  481 
Acoma  458 
Acontiolaimus  462,  465,  471, 
474,  481 
Acrobeles  470,  471,  475,  476 
Acrobeloides  470,  471,  475,  476 
Acrostichus  463,  464 

page 
Bolbinium  454,454 
Bolbolaimus  463,  464,  466 
Bolbonema  455,  477 
Brachynema  458 
Brachynemella  458 
Bradylaimus  465 
Bradynema  455,  458,  460 
Bulbopharyngiella  .  .  .463,  464.  466 
Bunonema  •.  .  475 
Butlerius  466,468 

page 
Cylindrolaimus  479,  480 
Cynura  431 
Gytolaimium  457,  457,  473,  474 

r)actium  466 
*f     Dactylaimus  473  ,  480 
Dactylonema  456,  478,  480 
Dagda  467,  468 
Daptonema  467,  472.  473,  473 
Dasylaimus.  .470,  470,  471,  471,  471, 

Actinonema  456,  461,  472,  478 
Aculeonchus  460 
Adoncholaimus  469,  469 
Aegialoalaimus  455,  477 
Alaimella  457,  457,  479,  479 
Alaimonema.  ..  .454,  466,  466,  470, 
476 
Alaimus  454,  454,  456,  457 
AJlantonema.  .  .  .455,  458,  459,  459, 
460,460 
Allomonhystera  473 
Amphispira  464,  464,  470,  470 
Amphistenus  463,  469 
Anaxonchium  462,  468 
Anguillula  463,  468,  470 
Angustinema  478,  481 
Anoncholaimus  462,  479,  481 
Anonchus  476,  479 
Anoplostoma  478,  478 
Antholaimus  460,  461 
Anthonema  454,  475,  477 
Anticoma                       458  472   474 

Caconema  459,459 
Calyptronema  .  .  .462,  463,  465,  469 
Camacolaimus  462,  465,  471, 
474,  481 
Campydora  460,  460,  461.  463, 
464,  464 
Campylaimus  456,  472,  478 
Catalaimus  462,  463,  465,  469 
Catanema  454,  454.  466,  470, 
470,  474,  476 
Cenolaimus  473,  479 
Cephalobus  470,  471,  475,  476 
Cephalonema  461,  463 
Ceramonema.  .  .  .454,  456,  456,  475, 
479 
Chaetonema  479 
Chaetosoma.  .454,  455,  470,  475,  477 
Chambersiella  466,  476,  477 
Chaolaimus....459,  459,  461,  475, 
475,  476 
Cheilobus  470,  476 

Dasynemeila  470',  472',  476',  479 
Deltanema  466,  471,  476 
Demania  Southern  467 
Demania  Steiner  463,  469 
Demaniella  463,  469 
Demonema  468,474 
Dentatonema  462 
Denticulella  454 
Deontolaimus  457 
Deontostoma.  .  .  .461,  463,  472,  472, 

Dermatolaimus  477 
Desmodora  465,  466 
Desmodorella  465 
Desmolaimus  471,  476 
Desmoscolex.  .  .  .456,  456,  456,  456, 
457,  458,  478,  478,  478,  479, 
480,  480 
Diastolaimus  466,  476,  477 
Dicriconema  468.  469 
Didelta  472,  473,  478,  480 

Anticomopsis  458,  472,  474 
Anticyathus  457,  473,  480 
Anticyclus  462 
Antomicron  454,  457,  470,  472 
Antopus  455,  456 
Aphanolaimus...4S8,  474,  474,  480 
Aphelenchoides  459,  460,  460, 
475 
Aphelenchulus  458,  478,  479 
Aphelenchus  460,  460 
Aplectus  455,  471,  477,  481 
Apodontium  456,  457,  467 
Aponchium  465,  466,  466 
Araeolaimoides  456,  478,  480 
Araeolaimus  457,  474,  480 
Archepsilonema  455,  477 
Archionchus        459    459    461,  475, 

Chloronemella  476 
Choanolaimus  474 
Chondronema  455,  460 
Choniolaimus  470,  476 
Chromadora  463,  464,  466 
Chromadorella  465,  467 
Chromadorina  465,  466 
Chromadorissa  463 
Chromadorita  463,  463 
Chromadoropsis  465,  465 
Cbromagaster  476 
Chromaspirina  466,  469 
Chronogaster  470,  475 
Chrysonema  461 
Cinctonema  454,  470 
Cobbia  468 

481 
Dignathonema  466 
Dilaimus  463,469 
Dintheria  472 
Diodontolaimus....467,   467,   468, 

Dioncholaimus  468 
Dipeltis  461,  463 
Diphtherophora....459,   459,  461, 
475,  475,  476 
Diplogaster  463,  464,  465,  465. 
466,  466,  475 
Diplogasteroides  464,  465,  476 
Diplohystera  474 
Diplolaimella  473,  473 
Diplolaimus  471 

475,  476 
Ascolaimus  470,  472 
Asconema  455 
Asymmetrella  462,  478,  479 
Asymmetrica  471 
Atractonema  455 
Atylenchus                                  459 

Coinonema  456,  478,  480 
Colpurella  476,  478 
Comesoma  462,  464 
Conolaimella.  .  .  .  473,  473,  479,  479 
Conolaimus  465,  467,  467 
Convexolaimus  468 
Cophonchua                          462   472 

Diploseapter  !"!!!'.'....  465 
Diploscapteroides  463,  475 
Discolaimus  461 
Disconema  454 
Discophora  461,  463 
Dispira  467,472,479 

Aulolaimoides....470,  475,  476,  476 
Aulolaimus  475,  475 
Austronema  473 

Cothonolaimus  474,  481 
Craspedonema  475 
Crassolaimus  464 

Ditlevsenella.  .  .  .                    ...  469 
Ditlevsenia  461,478 

Axonchium  461 
Axonolaimus  467,  468,  470,  472 

Barbonema  457 
Bastiania  457,458 
Bathyepsilonema  455,  477 
Bathylaimella  479,  480 
Bathylaimus  Cobb  474,  481 
Bathylaimus  Ditlevsen.  .  .470,  472 
Bitholinema  477 
Bognenia  473 
Bolbella  462,464,469 

Cricolaimus  454,  466,  470,  476 
Criconema  459 
Croconema  469 
Cryptolaimus.  .  .  .454,  455,  471,  476 
Cryptonchus  461,  478 
Crystallonema  467,  470,  473, 
476,  479 
Cyartonema  455 
Cyatholaimus  462,  474 
Cyathonchus  462 
Cylicolaimus  469,  472,  474,  480 
Cylindrogaster  ...  475 

Dolicholaimus  467 
Dorylaimellus  461 
Dorylaimopsis  460,  468 
Dorylaimus  461,  461 
Doryllium  459,  461 
Doryonchus  461,  462 
Draconema.  .454,  455,  470,  475,  477 
Drepanonema.  .  .454,  455,  470,  475, 
477 

T^cphyadophora  458,  458 
&  Eleutherolaimus  467,  479 

INDEX 


489 


page 
Enchelidium  455,  456,  457 
Endolaimus  466 

page 
Leptolaimus  477 

page 
Odontophora  465,  467,  467 

Enoplocheilus  460,  461,  468 

Leptonemella.  .  .  .454,  454,  470,  470 

Oionchus                               461  '  464 

Enoploides  467,  468 
Enoplolaimus  467,  468 
Enoplostoma                        467   468 

Leptosomatides  457,  473 
Leptosomatum  458 

Oistolaimus  460,  464 
Omicronema  480 

Enoplus  467,468 
Epsilonella  455,477 
Epsilonema  455,  477 
Epsilonoides  455,  477 
Ethmolaimus  465 
Euchromadora  461 

Linhomoella.  .  !  .'  .'455,'  457,  457,'  474, 
476,  476,  480 
Linhomoeus  455,  457,  457,  466, 
471,474,480 
L.  obtusicaudatus  457 
Linolaimus  477 

474,  477,  481 
Oncholaimellus  469 
Oncholaimium  468 
Oncholaimus  468 
Onchulella  460,  460 
Onchulus  461 

Eudesmoscolex  454,  457 

Litinium  457,  457 

Onyx                      460  460  464  465 

Eulinhomoeus  (subgenus)  466 
Eumorpholaimus  480 

Litonema  454,  454,  474,  476 
Litotes.  .455,  456,  457,  478,  478,  479 

Oxystoma  457 
Oxystomina  .  .                     457,  457 

Eurystoma  462,  463,  469 
Eurystomina  462,  463,  469 

Longicyatholaimus  462 
Lycolaimus  475 

"panagrolaimus           470  471   475 

Eutelolaimus  455,  471 

Eutylenchus  458 

T7enestrolaimus  469 
-Tpiacra  467,469 
Filipjeva  478 

Macrolaimus  Ditlevsen  474, 
481 
Macrolaimus  Maupas  463,  464, 
475,  476 
Macroposthonia  455,  471 

Paracanthonchus.  .....  !  ....  .  .  .'  462 
Parachromagaster  479 
Paracothonolaimus  466 
Paracyatholaimus  462 
Paradesmolaimus  480 

Filoncholaimus  ...  469 
Fimbria  467,  467,  477,  479 
Fimbriella  478 

Marionella  462,  463,  469 
Meloidogyne  459,  459 
Meroviscosia  469 
Mesodorus  466,  469 

Paramonhystera  473 
Paranticoma  472,  479 
Paraphanolaimus  477,  480 

Fusonema  466 

Mesonchium  .  .  .  .466,  466,  466,  468, 

Paraplectus                           477   480 

468 
Metachromadora  465,  465 

Parasabatieria  457,  462,  464, 

Gammanema  467,  467 
Gonionchus  468 
Graphonema  461 

Metalaimus  473 
Metalinhomoeus  466,  471,  476 
Metepsilonema  455,  477 

Parasitaphelenchus  459,  460, 
460,  475 
Parasphaerolaimus  473 

Gullmarnia  .'  478 
Gymnolaimus  475,  478 

Micoletzkyia  456 
Microlaimua  464 

Paratylenchus  459 
Parenoplus  468,  472,  474 

Mitrephorus                          454  454 

Pareuchromadora  461,462 

ij-  Halalaimus  456,  456 
Halanonchus  479 
Halaphanolaimus        454,455  457, 

Molgolaimus  454 
Monhystera  457,  470,  470,  472, 
473,  476,  476,  478 

Parironus  467 
Paroncholaimus  469 
Paroxystomina                     456  472 

458,  476,  477,  480,  480 
Halenchus  458,  459 
Halichoanolaimus.  .  .  .468,  474,  480 
Halinema  480,480 
Haliplectus  455,  476,  477 
Helalaimus  457 

M.  dintheriana.  .  .470,  472,  476,  478 
Monhysteriella  470 
Monhystrella  (subgenus).  .470,  476 
Monhystrium  467,  473,  473 
Mononchoides  465,  466 
Mononcholaimus  461,  462 
Mononchulus                       461  468 

Pathoaphelenchus  459,  460, 
460,  475 
Pelagonema  472,  474,  478,  479, 
481 
Pelagonemella  476 
Penzancia  473 

Mononchus  462,  468,  469 

Peronilaimus                              475 

Heterodera  459,  459 
Heterodesmodora  471 
Hexatylus  458 
Himatidiophila  471,  471 
Hoplolaimua  458,  459 
Howardvua  456,  458,  458,  460 
Hypodontolaimus  463,  464 

Monoposthia  464 
Myctolaimus  475 
Myolaimus  466 

Nannolaimus  458,  474 
Nannonchus  462,469 
Nanonema  461,  463 
Nasinema  472 

Phanoderma  472,  472 
Phanodermella  456 
Phanodermopsis  458,  474,  480 
Pharetrolaimus  458,  459 
Platycoma  457,  458,  480.  480 
Platycomopsis  456,  478,  480 
Plectonchus  463,470 
Plectus                                 471  477 

I  Ilium  478 
lonema  456,456,458,481 
Iota  459,459 

Nemanema  457,  473 
Nemanemella  457 
Nemella  455,456 

Poikilolaimus  463,  464 
Polydontus  468 
Polygastrophora  463,  465,  469 
Polylaimium  477,477 

lotadorus  463,  464,  464 
lotalaimus  454,  456 
lotonchium           454   454   460  460 

Neoaplectana  454,  455,  471 
Neocnromadora  464 

Polysigma  466 
Pomponema  462,  468 
Pontonema                                 460 

Ironella                                        467 

Porocoma                              456  478 

Praeacanthonchus  462 

Isolaimium  478,  478,  480 
Isonchus  460,460 
Isonemella                             462  479 

Neotonchus  464 
Neotylenchus  458,  459 

Prismatolaimus.  .478,  478,  479,  480 
Pristionchus  465,  466,  466 
Pristionema  458 

Jiigerskioldia  469 

Notochaetosoma  454,  455,  458, 
470,  475,  477 
Nuada  456 

ProchaetoBoma  455,  477 
Prochromadora  463,  463,  464 
Prochromadorella  465,  467 

T^lugea  458 
J*-  Krampia  471 

Nuadella  454,455 
Nudolaimus  473,  479 
Nudora                                463,  464 

Prodesmodora  465,  477 
Promononchus...456,  456,  458.461, 

Kreisia  477 

Laimella  454,  476 
Lasiomitus  455,  456,  457 
Laxonema  454,  454,  474,  476 
Laxus  455,471,477 
Ledovitia  462,463 
Leptogastrella  473 

Nunema  474 
Nygmatonchus  464 
Nygolaimus  461 

Hdontolaimus  460,  464,  464 
^  Odontonema  463,  465 
Odontopharynx  464,  465,  466, 
466,  468 

471,  472,  474,  478,  478,  480 
Prooncholaimus  468 
Prosphaerolaimus  462 
Pselionema  454,  456,  456,  461, 
475,  479 
Pseudoaulolaimus  480,  480 
Pseudochromadora  471,  471 
Pseudodilaimus  462 

490 


•page 
Pseudolella.  .465,  466,  470,  475,  478 
Pseudoncholaimus  468 
Pseudonchus  471,  477 
Pseudoparoncholaimus  469 

page 
Siphonolaimus  459,  460,  476 
Smalsundia                   468   474   480 

•page 
Triplonchium  459,  477 
Tripyla  456,  456,  458,  461,  471 
472,  474,  478,  478,  480 
Tripylium  467,  479 
Tripyloides  474,474 
Trischistoma.  ..  .461,  462,  472,  473, 
478,  479 
Trissonchulus  467 
Tristicochaeta  454,  455,  470, 
475,  477 
Trogolaimus  467,  472 
Tubolaimella                        467   479 

Solenolaimus  454,  476 
Southernia  457,  458 
Southerniella  480 
Sphaerocephalum  473,  479 
Sphaerolaimus  473 
Sphaerularia  455 
Spilophora  465 
Spilophorella                                463 

Pseudorhabditis  475 
Psilenchus  460 
Pteronium  472,  479 
Ptycholaimellus  463,  464 
Pulchranemella  479 
Punctodora  463,  464 
Pycnolaimus  466,  476 

Quadricoma  ....456,  457,  478,  478 
Rhabditella                              475 

SpUophorium  465 
Spira  455,  464,  465,  471,  471 
Spirina  455,  464,  465,  471,  471 
Statenia                                         465 

Tubolaimus  473,  479 
Turbatrix  463,  468,  470 
Tycnodora  456 
Tylenchinema  456,  460 
Tylenchodon  459 
Tylencholaimellus  458 
Tylencholaimus  459,  459 
Tylenchomorphus...455,  458,  459, 
459,  460,  460 
Tylenchorhynchus  459 
Tylenchulus  459,  459,  459 
Tylenchus  459,459 
Tylolaimophorus  458,  459,  460 
Tylopharynx  459,  475 

TTdonchus  464 
U   Uracanthus  455,460 

\7asculonema  472,  474,  478, 
"                                            479,  481 
Viscosia  469 

Walcherenia  ...  470 
Wilsonema  477 

Xanthodora  463,465 
Xennella                       456  478 

Steineria  Filipjev  456,  461 
Steineria  Ditlevsen  469 
Steineria  Stekhoven  and 
de  Coninck  473 
Steineriella  469 
Stenolaimus..456,  458,472,  472,  474 
Stephanolaimus  456,  458,  467, 
471,  473,  479 
Stilbonema  454,  455 
Symplocostoma  461,  462,  462, 
463,  469 
Symplocostomella.  .  .  .462,  463,  469 
Synodontium  466,  470 
Synonchiella  468 
Synonchium  467,  468 
Synonchus  469 

Rhabditidoides  475 
Rhabditis  463,  475,  475,  475, 
476,  477 
Rhabditoides                      470  475 

Rhabditolaimus  476 
Rhabditophanes  470,  476 
Rhabdocoma  .  .  .  .472.  472,  473,  474 
Rhabdodemania  467 
Rhabdogaster  455,  477 
Rhabdolaimus.  .  .464,  475,  475,  477 
Rhabdonchus  460,  460,  460 

Rhabdotodenna  469 
Rhadinema  473,  479 
Rhinema                              462  465 

Rhinonema  460,  460,  461,  462, 
463 
Rhips                    461,  464,  466  469 

Syringolaimus  465 

T»achyhodites  457,  473 
*  Teratocephalus.  .  .  .466,  471,  471, 
475,  475,  476,  477 
Terschellingia  454,  455,  471 
Thalassironus  467 
Thalassoalaimus  455,  456 
Theristus  467,  472,  473,  473 
Thoonchus                                   469 

Rhodolaimus  475 
Rhynconema  479 
Richtersia  458,  462,  473,  474, 
480,480 
Richtersiella  473,  474,  480,  480 

Qabatieria..457,  462,  464,  471,  473 
0  Saveljevia  468 

Xenolaimus  472 
Xenonema  465 
Xinema  460,468 
Xiphinema  459 
Xyala  467,473 

YPsilon  .  ..  .462,  465,  471,  474,  481 

Zalonema  471,477 
Zanema..467,  473,  473,  479,  479 
Zysonemella  457,  473,  479 

Thoracostoma  469 
Thoracostomopsis  460 
Trefusia  457 
Trichoderma  458,  480 
Trichodorus  461 
Tricoma  456,  457,  478,  478,  480 
Trigonolaimus  465,  467,  467 
Trilepta  461,  477,  478 
Trileptium  461,477,478 
Trilobus  461,  469,  472,  472 
Triodontolaimus  467 

Scaptrella  467 
Scatonema                                     455 

Schistodera  457,  457 

"Sectonema  461 
Seinura  459,  460,  460,  475 

Sela/ihinema  ,                      ,468 

Seleneella  466 
Seuratia  462 
Seuratiella                                     462 

Sigmophora  465 

/ 


6739 


UNIVERSITY  OF  CALIFORNIA  AT  LOS  ANGELES 

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This  book  is  DUE  on  the  last  date  stampqfl|fci|]|p0 


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